Treatment of spinal muscular atrophy

Abstract

Disclosed herein are methods of treating spinal muscular atrophy in a subject. A particular method includes applying a therapeutically effective amount of an electrical stimulus to sensory neurons innervating a body region of the subject having motor damage due to the spinal muscular atrophy, where application of the electrical stimulus treats the motor damage due to spinal muscular atrophy in the subject; the method is combined with administration of SMA therapy.

Description

Cross-reference to related applications

[0001] This application claims the benefits of U.S. Provisional Application No. 63 / 461,545, filed April 24, 2023; U.S. Provisional Application No. 63 / 510,880, filed June 28, 2023; U.S. Provisional Application No. 63 / 609,235, filed December 12, 2023; and U.S. Provisional Application No. 63 / 550,939, filed February 7, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to a method of treating spinal muscular atrophy (SMA) in a subject by stimulating sensory afferent nerves in the subject. This disclosure also relates to a method of treating SMA in a subject by combining electrical stimulation of the spinal cord with SMA therapy. Background Technology

[0003] SMA is a neurodegenerative disease caused by mutations in the surviving motor neuron 1 (SMN1) gene (Lefebvre et al., 1995. Cell 80(1):155-165). In SMA patients, affected motor neurons (MNs; also known as “motor neurons”) have a poorer ability to generate sustained firing and may degenerate over time, leading to MN death. Notably, although the SMN1 gene is universally expressed in all MNs, not all muscles are affected. SMA particularly affects the lower extremities and, in more severe cases, respiratory function. Experiments in mouse models have shown that insufficient expression of the SMN protein initially causes dysfunction and later leads to MN death (Le et al., 2005. Human Molecular Genetics 14(6): 845–57; Avila et al., 2007. J Clinical Investigation. 117(3):659-671). In other words, many (if not all) MNs in SMA patients are nonfunctional or dead, especially in patients with advanced SMA. Furthermore, even in the muscles affected by SMA, not all neurons exhibit dysfunction (Fletcher et al., 2017. Nat Neuroscience 20 (7): 905–16; Mentis et al., 2011. Neuron 69 (3): 453–67), suggesting that muscle weakness is caused by dysfunction of a certain percentage of neuronal neurons (MNs) rather than their death. Therefore, MN dysfunction and MN death in SMA patients are two independent processes.

[0004] The SMN gene has been localized to a complex region on chromosome 5q via linkage analysis. In humans, this region contains an inverted repeat of approximately 500 kb, producing two nearly identical copies of the SMN gene. SMA is caused by inactivating mutations or deletions of telomere copies of the gene (SMN1) on both chromosomes, resulting in loss of SMN1 gene function. However, patients retain a centromere copy of the gene (SMN2), and the copy number of the SMN2 gene in SMA patients is generally negatively correlated with disease severity; that is, patients with less severe SMA have more copies of SMN2. However, SMN2 cannot fully compensate for the loss of SMN1 function due to alternative splicing of exon 7 caused by translational silencing CT mutations in exon 7. Therefore, most transcripts produced by SMN2 lack exon 7 (47SMN2) and encode a truncated SMN protein with impaired function and rapid degradation.

[0005] The SMN protein is thought to play a role in RNA processing and metabolism, with a well-characterized function of mediating the assembly of a specific class of RNA-protein complexes called snRNPs. SMN may have other functions within MN, but its role in preventing selective denaturation of MN has not been clearly determined.

[0006] In most cases, SMA is diagnosed based on clinical symptoms and by the presence of at least one copy of the SMN1 gene. However, in approximately 5% of cases, SMA is caused by gene mutations other than SMN1 inactivation, some of which are known, but others are not yet clear. In some cases, when SMN1 gene testing is not feasible or does not show any abnormalities, other tests, such as electromyography (EMG) or muscle biopsy, may be indicated.

[0007] Several SMA mouse models have been developed. In particular, the SMN delta exon 7 (Δ7 SMN) model (Le et al., Hum. Mol. Genet., 2005, 14:845) carries several copies of both the SMN2 gene and Δ7 SMN2 cDNA and reproduces many phenotypic features of type 1 SMA. The Δ7 SMN model can be used for SMN2 expression studies and assessment of motor function and survival. The C / C-allele mouse model (Jackson Laboratory strain #008714, The Jackson Laboratory, Bar Harbor, ME) provides a less severe model of SMA in mice where both full-length SMN2 (FL SMN2) mRNA and SMN protein levels are reduced. The C / C-allele mouse phenotype has the SMN2 gene and a mixed mSMN1-SMN2 gene undergoing alternative splicing, but without significant muscle weakness. The C / C-allele mouse model is used for SMN2 expression studies.

[0008] SMA severity ranges from respiratory failure in the neonatal period (types 1-2) to mild muscle weakness appearing in adulthood (type 4). Infantile SMA is the most severe form of this neurodegenerative disorder. Symptoms include muscle weakness, poor muscle tone, weak cry, weakness in the limbs or frequent falls, difficulty sucking or swallowing, buildup of secretions in the lungs or throat, difficulty feeding, and increased susceptibility to respiratory infections. The legs are often weaker than the arms, and developmental milestones such as lifting the head or sitting up are not met. Generally, the earlier symptoms appear, the shorter the lifespan. Symptoms appear soon after the degeneration of MN cells. The severe forms of the disease are fatal, and there is no known cure for any form. The course of SMA is directly related to the rate of MN cell degeneration and the resulting severity of weakness. Infants with severe forms of SMA often die from respiratory illnesses due to weakness in the muscles that support breathing. Children with milder forms of SMA live much longer, but they may require extensive medical support, especially those at the more severe end of the range. The clinical scope of SMA has been divided into the following five groups:

[0009] ● Type O SMA (intrauterine SMA) is the most severe form of the disease and begins before birth. Typically, the first symptom of type O SMA is reduced fetal activity, which can be first observed between 30 and 36 weeks of gestation. After birth, these newborns are rarely active and experience difficulty swallowing and breathing.

[0010] ● Type 1 SMA (infantile SMA or Werdnig-Hoffmann's disease) presents with symptoms between 0 and 6 months of age. This form of SMA is also very severe. Patients never gain the ability to sit up independently and usually die within the first 2 years without respiratory support.

[0011] ● Type 2 SMA (intermediate SMA) has an age of onset between 7 and 18 months. Patients acquire the ability to sit independently without support, but never stand or walk independently. The prognosis in this group depends largely on the extent of respiratory involvement.

[0012] ● Type 3 SMA (juvenile SMA or Kugelberg-Welander disease) is usually diagnosed after 18 months. Individuals with type 3 SMA are able to walk independently at some point during the course of their disease, but often require a wheelchair during adolescence or adulthood.

[0013] ● Type 4 SMA (adult-onset SMA). Weakness typically begins in late adolescence in the tongue, hands, or feet, and then spreads to other parts of the body. Adult-onset SMA has a much slower progression and has little or no impact on life expectancy.

[0014] SMA differs from other types of motor injuries, such as those caused by spinal cord injury or stroke, because the nonfunctional MN is the underlying cause of SMA-related injuries. The MN in patients with spinal cord injury or stroke lacks underlying cellular pathophysiology. Therefore, if these patients' MNs receive appropriate excitatory input, they are expected to respond. In contrast, the MNs in SMA patients, who possess cellular pathophysiology due to genetic mutations in the SMN1 gene, do not respond appropriately to excitatory input, as the MNs themselves are dysfunctional or dead. Therefore, SCS designed to increase excitatory input to the spinal MN is not expected to produce effects in SMA patients similar to those observed in other conditions treated with SCS, such as spinal cord injury, stroke, and pain, where the MNs remain functional.

[0015] Traditional methods for treating sports injuries, such as exercise or physical therapy, may not be effective in treating SMA when used alone, because neither exercise nor physical therapy increases the activation rate of muscle cells recruited by the neuromuscular junction (MN). The reduced activation rate of MN in SMA patients prevents adequate muscle cell engagement and leads to reduced sensory input from the central nervous system. Therefore, treatments that improve MN activation and function to recruit more muscle cells are needed to improve the quality of life for SMA patients. Neurorehabilitation agents such as onasemnogene abeparvovec (Zolgensma®) (an IV-administered, adeno-associated virus vector-based gene therapy that delivers a copy of the SMN1 gene); nusinersen (Spinraza®) (an intrathecally delivered antisense oligonucleotide (ASO) therapy targeting the SMN2 gene); and risdiplam (Evrysdi®) (an oral SMN2 splicing modulator) can be used to slow or prevent MN death due to SMA. Sovalrevir, nusinersen, and lisprexa are gene therapies designed to treat SMA by increasing the production of SMN protein. As presented in this article, SMA is caused by the deletion or mutation of the SMN1 gene, which leads to selective degeneration of the SMN-deficient MN. Although human subjects retained several copies of the SMN2 gene, the small amount of functional SMN protein expressed from SMN2 cannot fully compensate for the loss of SMN that should be expressed from the SMN1 gene.

[0016] Sovalprevir is a neurorehabilitation agent, and more specifically, a gene therapy, and more specifically, a recombinant self-complementary AAV9 containing a transgene encoding a protein of the human surviving motor neuron (SMN), under the control of a cytomegalovirus enhancer / chicken-β-actin heterozygous promoter. Intravenous administration of sovalprevir leads to cell transduction and SMN protein expression.

[0017] Nusinersen is a neurorejuvenator, and more specifically, a gene therapy, and more specifically, an antisense therapy that alters the splicing process of the SMN2 precursor RNA by inhibiting splicing factors. Specifically, nusinersen binds to a specific sequence in an intron downstream of exon 7 of the SMN2 transcript. This facilitates the integration of exon 7 into the mRNA, thereby enhancing the level of full-length SMA protein.

[0018] Lispritz is a neurorejuvenating agent, and more specifically a gene therapy, and more specifically a small molecule splicing regulator that increases exon 7 of SMN2 in the mRNA transcribed from the SMN2 small gene, and increases exon 7 of SMN1 in the mRNA transcribed from the SMN1 small gene. The small genes reproduce the alternative splicing response of exon 7 in both SMN2 and SMN1, resulting in exon 7 skipping in most SMN2 and SMN1 transcripts.

[0019] Using these neurorehabilitation agents and / or gene therapies alone may not be entirely effective for all patients, and is particularly ineffective in restoring motor function. Therefore, new therapies that target motor injuries in SMA patients and improve the effectiveness of current treatments are needed to improve the quality of life for these patients. Summary of the Invention

[0020] This document provides an embodiment of a method for treating spastic angiomyoliposuction (SMA) in a subject. The method includes applying a therapeutically effective amount of electrical stimulation to sensory neurons innervating a body region of the subject that has motor impairment due to SMA, wherein the electrical stimulation is applied via one or more electrodes controlled by a neurostimulator, and wherein the application of the electrical stimulation treats the motor impairment of the subject due to SMA. In some embodiments, the treatment of SMA includes a combination of neuromuscular stimulation and a neurorehabilitation agent. In some embodiments, the neurorehabilitation agent is a gene therapy, such as sovalprevir, nusinersen, or lispiracil.

[0021] The foregoing and other objects, features, and advantages of the embodiments will become more apparent from the following detailed description with reference to the accompanying drawings. Attached Figure Description

[0022] Figures 1A to 1G illustrate various models of SCS enhancement based on MN output according to some embodiments.

[0023] Figures 2A to 2C show graphs illustrating force enhancement during simulated autonomous brain input according to descriptions of some embodiments.

[0024] Figure 3A illustrates SMA-affected neuronal models with various ion channels according to some embodiments, wherein delayed rectified potassium channels (K-dr) are blocked.

[0025] Figure 3B illustrates an MN model with various ion channels, including a specific delayed rectified potassium channel (Kv2.1), according to some embodiments.

[0026] Figures 4A through 4C illustrate various HUMAC® Norm configurations according to some embodiments to test maximum torque in different joints of SMA patients receiving SCS stimulation of sensory neurons innervating the lower limbs.

[0027] Figures 5A and 5B illustrate isokinetics (e.g., HUMAC® Norm isokinetics) configured according to some embodiments to test hip flexion and knee extension in SMA patients, respectively.

[0028] Figure 6 shows a comparison between the position of the electrodes during surgery and the position after surgery in SMA patients according to some embodiments.

[0029] Figures 7A to 7E show various torque measurements over time for two SMA patients according to some embodiments.

[0030] Figures 8A and 8B illustrate how spinal cord stimulation, according to some embodiments, increases maximum hip flexion during movement in SMA patients.

[0031] Figures 9A and 9B illustrate that spinal cord stimulation of subjects, according to some embodiments, only temporarily disrupts the balance of SMA patients.

[0032] Figure 10 illustrates the maximum rate at which SCS robustly increases in SMA patients according to some embodiments.

[0033] Figures 11A and 11B show the effect of SCS on hip flexion in SMA patients at the end of the study according to some embodiments.

[0034] Figures 12A to 12F show the improvement in right knee extension at the end of the study in two SMA patients according to some embodiments.

[0035] Figures 13A to 13C show the improvement in left knee extension in SMA patients at the end of the study, according to some embodiments.

[0036] Figures 14A to 14C show the improvement in right hip flexion at the end of the study in SMA patients according to some embodiments.

[0037] Figures 15A to 15C show the improvement in left hip flexion at the end of the study in first SMA patients according to some embodiments.

[0038] Figures 15D to 15F show the improvement in right hip extension at the end of the study in a second SMA patient according to some embodiments.

[0039] Figure 16 shows manual muscle test scores of SMA patients with and without stimulation, according to some embodiments, based on muscle and treatment course.

[0040] Figures 17A to 17C show the distances traveled by two SMA patients during a six-minute walk test across different treatment sessions, according to some embodiments, comparing stimulation off versus stimulation on.

[0041] Figures 18A to 18C show the Hammersmith Functional Motor Scale extended score and the revised Hammersmith Scale score for two SMA patients according to some embodiments.

[0042] Figures 19A to 19D show the principal component analysis (PCA) results of two SMA patients according to some embodiments.

[0043] Figures 20A to 20H illustrate short-term improvements in several gait quality variables in two SMA patients when comparing stimulation off versus stimulation on, according to some embodiments.

[0044] Figures 21A to 21D show the effects at the end of a study on gait patterns in two SMA patients during a 6-minute walking test, according to some embodiments.

[0045] Figures 22A to 22H show the improvements in several gait quality variables at the end of the study in two SMA patients according to some embodiments.

[0046] Figures 23A and 23B show the neural activation results of a first patient during an active task according to some embodiments.

[0047] Figures 24A and 24B show the neural activation results of a second patient during an active task according to some embodiments.

[0048] Figures 25A and 25B show the neural activation results of a first patient during a passive task according to some embodiments.

[0049] Figures 26A and 26B show the MN activation rate during maximal voluntary contractions at different time points during and after the study in SMA patients according to some embodiments.

[0050] Figures 27A and 27B show the changes in torque measurements of SMA patients at the end of the study according to some embodiments.

[0051] Figures 28A and 28B show a short-term increase in torque measurements in SMA patients when comparing stimulation off versus stimulation on, according to some embodiments.

[0052] Figures 29A to 29C show the changes in MN input resistance in SMA patients at the end of the study according to some embodiments.

[0053] Figures 30A to 30C illustrate, according to some embodiments, the long-term changes in torque measurements in two SMA patients when comparing SMA treatment with (Figures 30B and 30C) versus no SMA treatment (Figure 30A). The SMA treatment administered was nusinersen (Spinraza®).

[0054] Figures 31A through 31H illustrate, according to some embodiments, the long-term changes in several gait quality variables in two SMA patients when comparing SMA treatment with (Figures 31E through 31H) versus no SMA treatment (Figures 31A through 31D). The SMA therapy administered was nusinersen (Spinraza®).

[0055] Figure 32 shows a table of optimal current values ​​and lead configurations for each SMA patient.

[0056] Figure 33 shows the discomfort rating scale for each SCS stimulation configuration provided by individual SMA patients.

[0057] Figure 34 uses a network diagram to show the percentage increase in absolute torque at all assessed joints during the study of two SMA patients compared to the pre-study assessment during the isometric task.

[0058] Figure 35 shows the torque generated by a first-degree SMA patient during maximal isometric contraction in various movements.

[0059] Figure 36 shows the torque generated by a third-degree SMA patient during maximal isometric contraction in various movements.

[0060] Figures 37A and 37B show the joint angles at different time points when the SCS is closed, as well as the gait cycle curves with and without the SCS in three different SMA patients.

[0061] Figure 38 shows the ROM tables for the hip and knee joints of three SMA subjects before and after the study, and with SCS on and off. The comparisons before and after the study were made at week 4 against baseline (or week 3 for SMA01).

[0062] Figure 39 shows the z-score analysis associated with spinal cord fMRI during activity in each SMA patient.

[0063] Figure 40 uses a network diagram to show the percentage change in MEP peak amplitude for each participant and each muscle during TMS at rest, compared to pre-implantation, at week 4 for SMA01.

[0064] Figure 41 shows the TMS recruitment curves of the second SMA patient before implantation, during week 3 of the study, and after removal.

[0065] Figure 42 shows the TMS recruitment curves of SMA03 before implantation, during week 3 of the study, and after removal.

[0066] Figures 43A to 43C show bar graphs relating the number of units of single MN discharges from surface EMG signals, innervation area, and peak firing rate to three SMA patients during isometric maximal voluntary contraction as part of isometric knee extension exercises.

[0067] Figure 44 shows a scatter plot representing the long-term variation of isometric maximum torque measurements generated by left and right hip flexion in SMA patients SMA01 and SMA02. Negative numbers indicate treatment before implantation, numbers without (-) or (+) indicate treatment during the study period (with implant), and numbers with (+) indicate treatment after removal.

[0068] Figure 45 shows a table of fatigue values ​​for three SMA patients before, during, and after the study, which were measured based on the speed of the last lap of a 6MWT compared to the first lap.

[0069] Figure 46 shows the 6MWT lap speeds of three SMA patients.

[0070] Figure 47 shows a table of distances traveled by three SMA patients across different treatment intervals during the 6MWT period after SCS closure, specifically comparing distances before implantation, at the end of the study, and at follow-up. The numbers in parentheses indicate changes relative to baseline.

[0071] Figure 48 shows the improvement of the three SMA patients at 6MWT based on each patient's HFMSE score at the start of the study. The value "38" refers to the initial HFMSE score of SMA02; "49" refers to the initial HFMSE score of SMA03; and "60" refers to the initial HFMSE score of SMA01.

[0072] Figures 49A to 49C show various graphs of stride height, stride length, and gait speed to provide an overview of gait changes in three SMA patients during the study.

[0073] Figure 50 shows the TMS recruitment curves of the first SMA patient before implantation and at the end of the study.

[0074] Figures 51A to 51B show the trajectory of single motor neuron firing rates during maximum voluntary contraction under isometric conditions in the right knee of SMA03 before and after the study (Figure 51A) and with and without stimulation (Figure 51B).

[0075] Figures 52A and 52B provide the quantification of the mean peak ejaculation rate for each of the three SMA patients under all isometric conditions before and after the study (Figure 52A) and with and without stimulation (Figure 52B). Detailed Implementation

[0076] I. Introduction

[0077] This article provides a method for treating subjects with SMA. As discussed in detail herein, a therapeutically effective amount of electrical stimulation is applied to sensory neurons innervating a body region of a subject with motor impairment due to SMA via one or more electrodes controlled by a neurostimulator, thereby treating the subject's motor impairment caused by SMA. Without being bound by theory, it is believed that applying electrical stimulation to sensory neurons directly recruits monosynaptic and polysynaptic excitatory pathways in the spinal cord, which in turn increases the membrane potential and activation probability of the spinal cord MN innervating the body region of a subject with motor impairment due to SMA. This pathway recruitment can increase neural plasticity, thereby allowing the subject to regain motor function. Furthermore, in some embodiments, applying a therapeutically effective amount of electrical stimulation to the subject over time (e.g., for at least 2 hours / day during a period of at least 6 months, or for at least 1 hour / day during a period of at least 1 month) can lead to ion channel remodeling on the MN membrane, a sustained increase in the activation probability of the spinal cord MN, and improvement in motor impairment, even in the absence of stimulation. In embodiments, the treatment of SMA includes a combination of neuromuscular stimulation and a neurorehabilitation agent. In some embodiments, the nerve-restoring agent is a gene therapy, such as sovalprevir, nusinersen, or risperidone. In some embodiments, the nerve-restoring agent is risperidone.

[0078] Therefore, in one embodiment, therapeutic electrical stimulation can be applied to a subject by implanting or percutaneously placing electrodes under the control of an implantable or external neurostimulator. The electrodes and neurostimulator together constitute a system for delivering SCS to a subject to improve motor impairments caused by SMA (e.g., muscle weakness, muscle control, and / or speech deficits). This system can be used in combination with other SMA therapies, such as targeted motor rehabilitation, to improve patient outcomes.

[0079] Given the unique pathophysiology of SMA, applying SCS to SMA patients has produced unexpected results. As discussed above, SMA differs from other types of motor injuries, such as those caused by spinal cord injury or stroke, because the nonfunctional MN is the underlying cause of injury in SMA. Therefore, it is not expected that SCS designed to increase excitatory input to the spinal cord MN will produce effects in SMA patients similar to those observed in other conditions treated with SCS, such as spinal cord injury, stroke, and pain, where the MN remains functional.

[0080] However, as discussed below, significant immediate and end-of-study effects of SCS have been observed in SMA patients treated according to this disclosure. Surprisingly, the extent of the immediate effects of SCS in SMA patients is at least as significant as those observed in patients with stroke and spinal cord injury. More noteworthy is the extent of the end-of-study effects observed after only 4 weeks of treatment according to this disclosure, as discussed in detail below (e.g., related measurements such as: MN input resistance, MN excitation rate, torque generated at different leg joints, EMG signal, maximal voluntary contraction during knee extension and / or hip flexion, hip flexion during movement, balance, transition from seat to stand, maximum running speed, range of motion, muscle strength (manual muscle testing), gait (6-minute walk test), motor ability (Hammersmith Functional Motor Scale Extended and Revised Hammersmith Scale tests), and leg circumference). Specifically, the improvement in muscle strength is so great that it cannot be attributed solely to exercise. For example, in one study, a patient with SMA more than doubled their left hip flexion, even though the subject did not perform any hip strength training other than walking during the study. The subject's activity level remained unchanged relative to their pre-study activity level. These changes were also reflected in improvements observed on clinical outcome tests such as the manual muscle test, the revised Hammersmith Scale (RHS) test, and the 6-minute walk test. Furthermore, the data did not indicate a plateau, suggesting that prolonged use of SCS may lead to even greater improvements in patients with SMA.

[0081] The long-term effects of SCS varied among SMA patients over a period exceeding 50 days following SCS removal. Patients treated with SCS but not with SMA therapies (such as neurorejuvenators used to increase SMN protein production, e.g., sovalrevir, nusinersen, or liximab) experienced a gradual decline in certain activity parameters (e.g., measurements related to torque, movement, and gait at different leg joints). Conversely, those activity parameters did not decline in patients treated with SMA therapy in combination with SCS. Neither group experienced a decline in some clinical outcome parameters (e.g., RHS test), and one SMA patient treated with SMA therapy even experienced an increase in RHS parameters despite not receiving SCS treatment for more than 50 days. In conclusion, the data suggest that SMA patients treated with SMA therapy in combination with SCS may derive a longer long-term benefit from SCS compared to patients treated with SCS alone. In some embodiments, the SMA therapy administered in conjunction with SCS is sovalprevir, nusinersen, or liximab. In some embodiments, the SMA therapy is nusinersen or liximab. In still other embodiments, the SMA therapy is liximab.

[0082] According to some embodiments of this disclosure, application of SCS can artificially increase the activity of the same sensory afferent fiber (e.g., Ia) affected by SMA. This may have immediate (stimulus on and off during the study) and long-term (stimulus off before and after the study) effects on SMA patients. Without being bound by any particular theory, SCS can immediately increase excitatory input to MN, thereby increasing its activation rate. This can produce an immediate improvement in motor deficits. In the long term, the artificial increase in sensory afferent activity can enhance the affected sensory synapses and can reverse maladaptive changes in MN ion channels, thereby improving MN dysfunction that would lead to measurable changes in motor function. Therefore, SCS can address motor deficits caused by reduced presynaptic activity of sensory afferent fibers.

[0083] In some embodiments, SCS may be combined with pharmacological interventions designed to halt disease progression, such as drug therapies that increase SMN protein production. In embodiments, the drug therapy includes sovalprevir, nusinersen, or liximab. In some embodiments, the drug therapy is nusinersen or liximab. In still other embodiments, the drug therapy is liximab.

[0084] II. Abbreviations

[0085] CST corticospinal tract

[0086] DRG dorsal root ganglion

[0087] EMG electromyography

[0088] MN motor neurons

[0089] SCS spinal cord stimulation

[0090] Spinal muscular atrophy (SMA)

[0091] SMN1 surviving motor neurons 1

[0092] Transcranial magnetic stimulation (TMS)

[0093] III. Terminology Summary

[0094] Unless otherwise stated, technical terms are used in their conventional sense. As used herein, the term "comprises" means "comprising". Although many methods and materials similar to or equivalent to those described herein may be used, particularly suitable methods and materials are described below. For ease of viewing the various embodiments, the following explanations of terms are provided:

[0095] Approximately: As used herein, the term “approximately” refers to an approximation of a qualitative or quantitative measurement. Whether a measurement is qualitative or quantitative should be clear from its context. Regarding quantitative measurements, “approximately” means plus or minus 5% of a reference value. For example, “approximately” 100mA means 95mA to 105mA.

[0096] Dorsal root: a small branch of the root of a sensory neuron that originates from the posterior part of the spinal cord and extends to the dorsal root ganglion.

[0097] Lateral spinal cord: The region on the outer surface of the spinal cord, located between the dorsal midline and the point where the dorsal ramus roots enter the main spinal cord.

[0098] Electrical stimulation: Various types of electrical currents are selectively delivered to target locations in the subject (e.g., specific areas of the dorsolateral spinal cord) via one or more electrodes.

[0099] Electrode: An electrical conductor through which current can pass. An electrode can also be a current collector and / or emitter. In some embodiments, the electrode is solid and includes a conductive metal as a conductive layer. Non-limiting examples of conductive metals include noble metals or refractory metals and alloys, such as stainless steel, tungsten, platinum, iridium, tantalum, titanium, titanium nitride, and niobium. Electrodes can be interconnected or wired independently.

[0100] End-of-study effect: SCS-induced mid-term effect. Also known as the "post-study effect". As used in this article, "end-of-study" can refer to the effect measured approximately one week before or after the end of a four-week study, around the time the SCS electrodes are removed.

[0101] Immediate effect: An immediate (e.g., same-day) effect induced by SCS. Also known as an “auxiliary effect.” The immediate / auxiliary effect of SCS is measured by repeating the experiment at short time intervals with or without SCS. As used herein, “immediate” can refer to an effect measured over a four-week study period and involves the use of SCS.

[0102] Implantation: For example, using surgical techniques to place one or more electrodes or a device containing one or more electrodes, wholly or partially, into a subject's body. The device is partially implanted when a portion reaches or extends outside the subject. Implantable electrodes and devices can be epidurally implanted in the spinal cord, such as in a dorsolateral position. Electrodes or devices can be implanted for different durations, such as short-term (e.g., one or two days or less) or long-term or chronic (e.g., one month, six months, one year or longer), as in daily living assistive devices.

[0103] Long-term effects: Long-term (e.g., time spans of several months or more) effects induced by SCS. Also known as “therapeutic effects.” As described herein, “long-term” can refer to effects measured more than 50 days after electrode removal. The long-term effects of SCS can be identified based on changes in the intrinsic motor abilities of SCS subjects over time. These changes indicate the disease-improving effect of SCS and are measured when SCS is turned off, thus reflecting the true changes in motor control.

[0104] Sports injuries: partial or complete loss of function in body parts such as the legs, feet, arms, hands, fingers, neck, and trunk (e.g., respiratory muscles). Specific sports injuries include loss of muscle strength, partial paralysis (incomplete paralysis), loss of dexterity (such as finger movements), and uncontrollable muscle tone. Subjects may exhibit a variety of sports injuries as comorbidities of SMA.

[0105] Motor threshold: The minimum intensity of thalamic stimulation that can produce a given amplitude of motor output from a muscle in a resting (RMT) state or during muscle contraction (AMT).

[0106] Neurostimulator: An electrical stimulation device controlled by current or voltage. A neurostimulator controls the delivery of electrical pulses or pulse patterns with defined parameters, such as, but not limited to, pulse frequency, duration, amplitude, phase symmetry, duty cycle, pulse current, pulse width, and on / off time. The controlled electrical pulses are delivered through one or more electrodes (e.g., one or more wireless electrodes, or electrodes located at the end of a wire (thin insulated wire)) configured to apply electrical stimulation to a target tissue of a subject. A neurostimulator may include at least one multi-contact wire. A neurostimulator can be used to apply a series of electrical pulse stimuli (e.g., charge-balancing pulses) through at least one electrode; for example, but not limited to, low-frequency pulse sequence patterns, frequency-sequence pulse burst sequence patterns (e.g., where different modulated electrical stimulation sequences are generated at different pulse burst frequencies), and phase sequence patterns (e.g., where stimulation control parameters change in response to feedback from the subject's movement).

[0107] Perceptual threshold: The minimum intensity of electrical stimulation required for a conscious person to become aware of a specific sensation evoked by electrical stimulation.

[0108] Sensory neurons: Also known as afferent neurons, sensory neurons are nerve cells in the peripheral nervous system that are responsible for converting stimuli from the neuronal environment into internal electrical impulses and transmitting these impulses to the central nervous system.

[0109] SMA therapy: Neurorejuvenating agents, pharmacological therapies, and / or gene therapies (e.g., sovalprevir, nusinersen, or liximab) used to increase SMN protein production. SMA therapy may be administered to the subject before, during, and / or after the stimulation. In some specific embodiments, the SMA therapy is nusinersen or liximab, or more specifically, liximab.

[0110] Spinal muscular atrophy (SMA): A disease usually caused by inactivation mutations or deletions of the SMN1 gene on two chromosomes, resulting in the loss of SMN1 gene function.

[0111] Subject: A living multicellular vertebrate, including both humans and non-human mammals (including non-human primates, rats, mice, guinea pigs, cats, dogs, cattle, horses, etc.). Therefore, the term "subject" includes both human and animal subjects. The term "patient" is used interchangeably with the term "subject."

[0112] Therapeutic effective amount: The amount of a compound or treatment (or both) sufficient to provide a beneficial or therapeutic effect to a subject or a given percentage of subjects. Therapeutic effective amounts of a particular compound or treatment can be determined in many different ways, such as by measuring the reduction of a disease or condition (such as a motor injury caused by SMA). Therapeutic compounds and treatments can be administered once or multiple times (e.g., long-term administration over an appropriate period). However, the effective amount can vary depending on the source of administration, the subject being treated, the severity and type of the condition being treated, and the manner of administration.

[0113] Percutaneous placement: This refers to placing one or more electrodes or a device containing one or more electrodes on or near the skin surface of a subject, for example, using non-invasive techniques. The electrodes may be applied to the subject's skin surface to deliver electrical stimulation, for example, under the control of an external neurostimulator. The electrodes or device may be placed percutaneously for varying durations, such as short-term (e.g., one or two days or less) or long-term or chronic (e.g., one month, six months, one year or longer), as in everyday assistive devices.

[0114] Treatment / treatment: For a disease or condition (e.g., SMA), any term includes one or more of the following: (1) preventing the disease or condition, for example, preventing the clinical symptoms of the disease or condition from appearing in subjects who may be exposed to or susceptible to the disease or condition but have not yet experienced or shown symptoms of the disease or condition; (2) suppressing the disease or condition, for example, preventing the development of the disease or condition or its clinical symptoms; and (3) alleviating the disease or condition, for example, causing the disease or condition or its clinical symptoms to subside.

[0115] More specifically, treatment of SMA indicates at least one or more of the following beneficial effects: reduced muscle strength loss, increased muscle strength, reduced muscle atrophy, reduced loss of motor function, reduced contractures, increased MN, reduced MN loss, protection of SMN-deficient MN from degeneration, increased motor function, increased lung function, reduced loss of lung function, and / or improved quality of life.

[0116] More specifically, treatment for SMA refers to the ability or maintenance of certain actions (such as sitting up independently) in human infants or young children, or the ability or maintenance of certain actions (such as standing independently, walking independently, running independently, breathing independently, turning independently during sleep, or swallowing independently) in human infants, young children, children, or adults.

[0117] IV. Stimulation of sensory neurons to treat SMA

[0118] This article provides a method for treating subjects (e.g., human subjects) with SMA. This method can be used to treat (i.e., prevent, improve, inhibit, and / or alleviate) motor impairment caused by SMA in subjects. The method involves applying a therapeutically effective amount of electrical stimulation to sensory neurons innervating a body region of the subject that has motor impairment due to SMA. The electrical stimulation can be applied, for example, via one or more electrodes controlled by a neurostimulator.

[0119] In one embodiment, applying electrical stimulation to sensory neurons increases the probability of activation rate of spinal cord MNs innervating body regions of subjects with motor impairment due to SMA. Without being bound by theory, it is believed that applying electrical stimulation to sensory neurons can directly recruit monosynaptic and polysynaptic excitatory pathways in the spinal cord, which can indirectly increase the membrane potential and activation rate of spinal cord MNs innervating body regions of subjects with motor impairment due to SMA. This pathway recruitment can increase neural plasticity, thereby allowing the subject to regain motor function.

[0120] The methods provided herein can be used to treat any suitable subject with a sports injury due to SMA or at risk of such an injury. The sports injury can be in a limb of the upper or lower body, such as above or below the elbow, or above or below the knee, or including the entire arm or leg. The subject may have any of SMA types 1-4, such as type 1, 2, 3, or 4. In some implementations, subjects with SMA are selected for treatment. The method can be initiated at any time after the onset of the subject's sports injury, or even before a detectable sports injury occurs in an SMA patient at risk of injury.

[0121] Applying a therapeutically effective amount of electrical stimulation to a subject with SMA can treat at least one motor injury caused by SMA in that subject. For example, applying a therapeutically effective amount of electrical stimulation can lead to a reduction in muscle weakness, an increase in muscle strength, a reduction in muscle atrophy, a reduction in motor function loss, an increase in motor function, an increase in lung function, and / or a reduction in lung function loss.

[0122] In some embodiments, the sports injury includes reduced control of a limb (such as the arm or leg), and the methods provided herein improve the subject’s control of the limb by at least 20% (such as at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%) relative to before treatment (as measured by any appropriate assessment indicator such as balance or strength indicators (e.g., sensory tissue tests)).

[0123] In some embodiments, the sports injury includes a decrease in postural balance and stability, and the methods provided herein improve the subject’s postural balance and stability by at least 20% (such as at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%) relative to before treatment (as measured by any appropriate assessment indicator such as a balance or strength indicator (e.g., a sensory tissue test)).

[0124] In some embodiments, the sports injury includes a reduction in leg torque, and the methods described herein improve the subject’s leg torque by at least 20% (such as at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%) relative to before treatment (as measured using the HUMAC® Norm system).

[0125] One or more electrodes can be placed in any suitable location to apply electrical stimulation to sensory neurons in the subject. In some embodiments, one or more electrodes are positioned to deliver electrical stimulation to one or more sensory neurons innervating a body region of the subject with a motor injury.

[0126] A spinal cord stimulation (SCS) system may include a neurostimulator and one or more spinal cord leads comprising multiple electrodes or contacts. The contacts of an SCS system can target specific muscles. For example, a contact located near spinal cord segment L2 can target the hip flexors, while a contact near spinal cord segment S1 can target the gluteal and ankle extensors. Therefore, the location of the contacts or electrodes can be selected to selectively target specific nerves innervating muscles affected by SMA. For example, if a human subject has significant deficiencies in the knee extensors and hip flexors, the stimulation system can be positioned to selectively target these muscles. Furthermore, to avoid adverse events, it may be advantageous or desirable not to stimulate certain nerves. For example, one or more electrodes comprising multiple nerves may be implanted, including those innervating muscles without motor impairment or with very low levels of motor impairment. Stimulation of muscles without motor impairment or with low levels of motor impairment can be uncomfortable or harmful. Therefore, in some embodiments, the number of sensory neurons stimulated is less than the number included in the electrode implant. That is, one or more electrodes are implanted in the subject, spanning multiple sensory neurons, but not all of these sensory neurons are stimulated.

[0127] In some embodiments, the placement of the SCS can be optimized and fine-tuned by stimulating various contact points in the SMA patient, measuring electrical activity (such as electromyography (EMG) signals) generated by muscles (e.g., agonist and antagonist muscles of various joints), and evaluating the measurement results. In one instance, during surgery, electrode placement is determined by stimulating each contact point and recording EMG signals of muscles from the trunk to the ankle. Stimulation of a specific contact point can begin at a low frequency (e.g., about 1 Hz) and gradually increase the amplitude of the stimulation until electrical activity associated with muscle activity in response to the stimulation is recorded. Based on the recorded electrical activity, one or more specific muscles targeted by a specific contact point can be identified, and thus, the stimulated contact point can be identified as the appropriate location for the electrode. The interpeak amplitude of the EMG waveform generated by the stimulation can be used to identify the response in the target muscle, thereby determining the correct muscle location. For example, a cephalic contact can generate its first waveform in the hip flexor muscles, while a caudal contact can generate its first waveform in the calf muscles. Stimulation can be repeated until the location of electrode activation is identified, for example, from the hip muscle with the cephalic contact to the calf muscle with the caudal contact. In other words, once the multiple contacts of the SCS system provide complete coverage of the leg muscles (e.g., from the hip to the ankle) for the purpose of applying SCS, the position of the lead can be fixed. In some embodiments, the identified location can be used for a second SMA patient exhibiting similar symptoms without requiring the above testing on the second SMA patient. In some embodiments, the above testing is performed during the procedure for electrode implantation.

[0128] In some embodiments, the body regions of the subject with a motor injury are selected from the lower back, hip, leg, ankle, and foot. In such embodiments, one or more electrodes are positioned to apply electrical stimulation to sensory neurons, such as sensory neurons of the T11-S1 nerve roots. For example, one or more electrodes may be implanted at the sensory nerve or DRG, or epidurally at the dorsal branch root or in a dorsolateral position of the spinal cord, for one or more sensory neurons of the T11-S1 nerve roots. In some embodiments, one or more electrodes are positioned to apply electrical stimulation to sensory neurons, such as sensory neurons of the L1-T11 nerve roots. In some embodiments, electrical stimulation is applied to at least the neurons covered by the positioning of one or more electrodes. Therefore, for example, in some embodiments, electrical stimulation is applied to the T11-S1 nerve root or a subset thereof, such as the T12-S1, L1-S1, L2-S1, L3-S1, L4-S1, L5-S1, T11-L5, T12-L5, L1-L5, L2-L5, L3-L5, L4-L5, T11-L4, T12-L4, L1-L4, L2-L4, L3-L4, T11-L3, T12-L3, L1-L3, L2-L3, T11-L2, T12-L2, L1-L2, T11-L1, or T12-L1 nerve root. In some embodiments, electrical stimulation is applied to the L1-S2 nerve roots or a subset thereof, such as the L1-S1, L1-L5, L1-L4, L1-L3, L2-S2, L3-S2, L4-S2, L5-S2, L2-S1, L2-L5, or L2-L4 nerve roots. In some embodiments, electrical stimulation is applied to the L1-S2 nerve roots. In some embodiments, two or more nerve roots independently selected from the group consisting of: T11, T12, L1, L2, L3, L4, L5, and S1 are stimulated. In some embodiments, three or more nerve roots independently selected from the group consisting of: T11, T12, L1, L2, L3, L4, L5, and S1 are stimulated. In some embodiments, four or more nerve roots independently selected from the group consisting of: T11, T12, L1, L2, L3, L4, L5, and S1 are stimulated. In some embodiments, the subject is also given SMA therapy, such as sovaprevir, nusinersen, or liximab. In some embodiments, the SMA therapy is nusinersen or liximab. In still other embodiments, the SMA therapy is liximab.

[0129] In some embodiments, the body regions of the subject with a motor injury are selected from the upper arm, shoulder, arm, hand, and respiratory muscles (such as the intercostal muscles or diaphragm). In some embodiments, the muscles are selected from the deltoid, biceps, triceps, and wrist extensor and flexor muscles of the arm. In such embodiments, one or more electrodes are positioned to apply electrical stimulation to sensory neurons, such as sensory neurons of the C3-T2 nerve roots. For example, one or more electrodes may be implanted at the sensory nerve or DRG, or epidurally at the dorsal branch root or dorsolateral aspect of the spinal cord, for one or more sensory neurons of the C3-T2 nerve roots.

[0130] In some embodiments, the body regions of the subject with a motor injury are selected from the upper arm, shoulder, arm, hand, and respiratory muscles (such as intercostal muscles or diaphragm). In some embodiments, the muscles are selected from the deltoid, biceps, triceps, and wrist extensor and flexor muscles of the arm. In some embodiments, respiratory muscles (such as intercostal muscles or diaphragm) are specifically not stimulated. In such embodiments, one or more electrodes are implanted in the epidural space of the C4-T1 vertebrae to apply electrical stimulation to one or more sensory neurons present in that space. In some embodiments, electrical stimulation is applied to the C4-T1 nerve roots or a subset thereof, such as the C4-C8, C4-C7, C4-C6, C4-C5, C5-T1, C5-C6, or C6-T1 nerve roots. In some embodiments, two or more nerve roots independently selected from the group consisting of: C4, C5, C6, C7, C8, and T1 are stimulated. In some embodiments, three or more nerve roots, independently selected from the group consisting of: C4, C5, C6, C7, C8, and T1, are stimulated. In some embodiments, SMA therapy, such as sovalprevir, nusinersen, or liximab, is also administered to the subject. In some embodiments, the SMA therapy is nusinersen or liximab. In still other embodiments, the SMA therapy is liximab.

[0131] In some embodiments, the body regions of the subject with motor injury are selected from the chest, chest wall, abdomen, upper back, and mid-back. In such embodiments, one or more electrodes are positioned to apply electrical stimulation to sensory neurons, such as sensory neurons of the T3-T10 nerve roots. For example, one or more electrodes may be implanted at the sensory nerve or DRG, or epidurally at the dorsal branch root or dorsolateral aspect of the spinal cord, for sensory neurons of the T3-T10 nerve roots. In some embodiments, electrical stimulation is applied to nerve roots T3-T10 or a subset thereof, such as nerve roots T3-T9, T3-T8, T3-T7, T3-T6, T3-T5, T3-T4, T4-T10, T4-T9, T4-T8, T4-T7, T4-T6, T4-T5, T5-T10, T5-T9, T5-T8, T5-T7, T5-T6, T6-T10, T6-T9, T6-T8, T6-T7, T7-T10, T7-T9, T7-T8, T8-T10, T8-T9, or T9-T10. In some embodiments, two or more nerve roots independently selected from the group consisting of: T3, T4, T5, T6, T7, T8, T9, and T10 are stimulated. In some embodiments, three or more nerve roots, independently selected from the group consisting of: T3, T4, T5, T6, T7, T8, T9, and T10, are stimulated. In some embodiments, four or more nerve roots, independently selected from the group consisting of: T3, T4, T5, T6, T7, T8, T9, and T10, are stimulated. In some embodiments, SMA therapy, such as sovalprevir, nusinersen, or liximab, is also administered to the subject. In some embodiments, the SMA therapy is nusinersen or liximab. In still some embodiments, the SMA therapy is liximab.

[0132] In some embodiments, the body regions of the subject with a motor injury are selected from the trunk, back, and upper limbs. This may include, for example, the chest, chest wall, abdomen, upper back, mid-back, upper arm, shoulder, arm, and hand. In some embodiments, muscles are selected from the deltoid, biceps, triceps, and wrist extensor and flexor muscles of the arm. In certain specific embodiments, one or more electrodes are implanted in the epidural space of the C4 to T1 vertebrae to apply electrical stimulation to one or more sensory neurons present in the space. For example, in some embodiments, one or more of the C5-T1 nerve roots, such as C5-C6, C5-C7, C5-C8, C6-T1, C6-C7, C6-C8, C7-T1, C7-C8, or C8-T1, are stimulated. In some embodiments, the C5-T2 nerve root, such as C5-T2, C6-T2, C7-T2, C8-T2, or T1-T2, is stimulated. In some embodiments, two or more nerve roots independently selected from the group consisting of: C4, C5, C6, C7, C8, T1, and T2 are stimulated. In some embodiments, two or more nerve roots independently selected from the group consisting of: C5, C6, C7, C8, T1, and T2 are stimulated. In some embodiments, two or more nerve roots independently selected from the group consisting of: C5, C6, C7, C8, and T1 are stimulated. In some embodiments, for each electrode, the stimulation amplitude is between 0.2 mA and 10 mA; the stimulation frequency is between 0.1 Hz and 500 Hz; and the pulse width is between 100 µs and 400 µs. In some embodiments, SMA therapy, such as sovalprevir, nusinersen, or liximab, is also administered to the subject. In some embodiments, the SMA therapy is nusinersen or liximab. In still some embodiments, the SMA therapy is liximab.

[0133] In some embodiments, electrode placement during surgery can be adjusted to account for postoperative electrode movement. This postoperative movement can be variable and difficult to avoid with non-permanent implants. For example, the electrode may move caudally or shift medially. Therefore, based on the predicted postoperative movement of the electrode, it can be implanted in an adjusted position during surgery such that, postoperatively, the electrode will move to a predefined optimal position. Further details regarding devices and surgical procedures that can be used to obtain chronic electromyography (EMG) recordings from leg muscles and to implant targeted spinal cord stimulation systems can be found in Capogrosso et al., 2018. Nature Protocols 13.2031-2061, which is incorporated herein by reference in its entirety.

[0134] Any suitable stimulation modality can be used to treat a subject's motor injury. In some embodiments, the electrical stimulation includes electrical pulses defined by parameters such as, but not limited to, amplitude, pulse width, and pulse frequency. Such electrical pulses can include charge-balancing pulses, such as cathode-preferred biphasic or monophasic charge-balancing pulses. In these and further embodiments, the electrical stimulation can be continuous or periodic.

[0135] The stimulation parameters of the SCS can be configured according to the techniques and values / ranges described herein. In one example, the electrical stimulation can be configured to include an electrical pulse having an amplitude of about 10 µA to about 10 mA, a width between about 40 µs and about 2 ms, and / or a frequency of about 10 Hz to about 2000 Hz. In one example, the electrical stimulation can be configured to have a preferred frequency of about 40 Hz. In some embodiments, for each electrode, the stimulation amplitude is between 0.2 mA and 10 mA; the stimulation frequency is between 0.1 Hz and 500 Hz; and the pulse width is between 100 µs and 400 µs.

[0136] In specific instances, electrical stimulation includes electrical pulses having an amplitude of about 10 µA to about 50 mA, such as about 10 µA to 10 mA, about 10 µA to about 1 mA, about 10 µA to about 100 µA, or about 100 µA to about 1 mA.

[0137] In specific instances, electrical stimulation includes electrical pulses having a pulse width between approximately 40 µs and approximately 2 ms; for example, between 40 µs and 2 ms, between 100 µs and 2 ms, between 200 µs and 2 ms, between 300 µs and 2 ms, between 400 µs and 2 ms, between 500 µs and 2 ms, between 600 µs and 2 ms, between 700 µs and 2 ms, between 800 µs and 2 ms, between 800 µs and 2 ms, between 900 µs and 2 ms, between 1 ms and 2 ms, between 1.5 ms and 2 ms, between 80 µs and 1.5 ms, between 100 µs and 1.5 ms, and between 200 µs. Between 1.5 ms, between 300 µs and 1.5 ms, between 400 µs and 1.5 ms, between 500 µs and 1.5 ms, between 600 µs and 1.5 ms, between 700 µs and 1.5 ms, between 800 µs and 1.5 ms, between 800 µs and 1.5 ms, between 900 µs and 1.5 ms, between 1 ms and 1.5 ms, between 1.5 ms and 2 ms, between 80 µs and 1 ms, between 100 µs and 1 ms, between 200 µs and 1 ms, between 300 µs and 1 ms, between 400 µs and 1 ms, between 500 µs and 1 ms Between 600 µs and 1 ms, between 700 µs and 1 ms, between 800 µs and 1 ms, between 800 µs and 1 ms, and between 900 µs and 1 ms.

[0138] In specific instances, electrical stimulation includes pulse frequencies between approximately 10 Hz and approximately 2000 Hz; for example, between 20 Hz and 100 Hz, between 20 Hz and 90 Hz, between 20 Hz and 80 Hz, between 20 Hz and 70 Hz, between 20 Hz and 60 Hz, between 20 Hz and 50 Hz, between 20 Hz and 40 Hz, and between 20 Hz and 30 Hz.

[0139] In some embodiments, the electrical stimulation includes an electrical pulse having an amplitude of about 10 µA to about 50 mA, a pulse width of about 40 µs to about 2 ms, and a pulse frequency of about 10 Hz to about 2000 Hz. In some embodiments, the electrical stimulation includes an electrical pulse having an amplitude of about 10 µA to about 10 mA, a pulse width of about 40 µs to about 2 ms, and a pulse frequency of about 10 Hz to about 1000 Hz. In some embodiments, the electrical stimulation includes an electrical pulse having an amplitude of about 100 µA to about 10 mA, a pulse width of about 40 µs to about 500 µs, and a pulse frequency of about 10 Hz to about 1000 Hz.

[0140] In some implementations, bipolar and / or tripolar stimulation may be used. In some implementations, for example, to target the muscles of the right leg, bipolar stimulation of the two cephalic contacts of the right lead is used to stimulate the spinal cord. In some instances, the electrical stimulation comprises electrical pulses with an amplitude of about 2 mA, a pulse width of about 400 µs, and a pulse frequency of about 40 Hz.

[0141] In some implementations, such as for targeting the muscles of the left leg, tripolar stimulation is used. In some instances, the electrical stimulation comprises electrical pulses with an amplitude of about 3.7 mA, a pulse width of about 400 µs, and a pulse frequency of about 40 Hz.

[0142] In some embodiments, the electrical stimulation includes an electrical pulse having an amplitude of less than about 10 mA, a pulse width between about 80 µs and about 2 ms, and a pulse frequency between about 20 Hz and about 100 Hz. In some examples, the electrical stimulation includes an electrical pulse having an amplitude between 0.5 mA and 5 mA, a pulse width between 80 µs and 200 µs, and a pulse frequency between 20 Hz and 80 Hz. For example, the electrical stimulation may include an electrical pulse having an amplitude between about 1.5 mA and about 3.5 mA, a pulse width between about 100 µs and about 200 µs, and a pulse frequency between about 40 Hz and about 80 Hz.

[0143] Electrical stimulation can be applied to the subject for any suitable amount of time necessary to achieve positive functional benefits for the patient. In some embodiments, the electrical stimulation comprises a stimulation pattern of 2 to 5 pulses separated by pulse intervals of about 3 ms to about 10 ms, wherein the series is repeated at a frequency of about 10 Hz to about 100 Hz. In some embodiments, the electrical stimulation is applied for at least 1 hour / day during a period of at least 1 month. In some embodiments, the electrical stimulation is applied for at least 2 hours / day during a period of at least 6 months.

[0144] In certain implementations, stimulation is applied at or below the subject's motor threshold and / or at or below the subject's perceptual threshold. For example, stimulation may be applied below the motor threshold and below the perceptual threshold, below the motor threshold but at or above the perceptual threshold, or below the perceptual threshold but at or above the motor threshold.

[0145] The SCS system can be configured within days to provide an electrical spinal stimulation protocol that allows for control over muscle extension and flexion during limb (e.g., each leg) movement, as well as real-time processing of gait kinematics and motor performance. In some implementations, subjects can be monitored and tested to establish parameters for electrical stimulation based on the subject's motor impairment and injury, for example, by monitoring one or more motor outputs that provide measurements of the degree of motor impairment and the subject's response to stimulation. In some implementations, electrical stimulation is delivered to sensory neurons in the subject via one or more electrodes while the subject performs voluntary activities or tasks affected by the subject's motor impairment; for example, forelimb tasks (e.g., reaching, grasping, picking up with the opposing thumb, gripping, and fine motor tasks involving precise finger movements) or lower limb tasks (e.g., walking, jumping, leg extension).

[0146] Once configured, stimulation bursts are delivered to specific spinal cord locations at precise timing to reproduce the natural spatiotemporal activation of the MN during movement. These protocols can also be readily adapted for safe implantation near the spinal cord and provide an SCS involving real-time motor feedback and a closed-loop controller, as discussed below. In some embodiments, parameters of the electrical stimulation controlled by the neurostimulator are adjusted based on changes in one or more motor outputs monitored while the subject performs a specific task, for example, to improve motor output and thus treat the subject's motor injury. In certain embodiments, the adjusted neurostimulator is part of an everyday assistive device to treat the subject over an extended period. In certain embodiments, once the subject is released from the clinical setting, the operation of the device and / or neurostimulator can be at least partially controlled by the subject. In these and further embodiments, the subject is taught how to use the device and / or neurostimulator. In some non-limiting embodiments, this treatment can increase input to the spinal cord MN membrane by directly recruiting sensory afferents from electrical impulses, and / or can lead to ion channel remodeling on the MN membrane to increase the activation rate probability of the spinal cord MN and / or improve motor impairment caused by SMA, including when electrical stimulation is no longer applied to the patient. Therefore, this disclosure includes methods for increasing the activation rate of motor neurons damaged by SMA.

[0147] Stimulating sensory afferent areas with implantable electrodes is an advanced neurosurgical procedure involving the implantation of one or more electrodes that deliver electrical stimulation under the control of an external or implantable neurostimulator unit. In instances where the neurostimulator is not externally positioned, the implantation of one or more electrodes and / or the neurostimulator is typically performed by a clinical team that includes neurologists, neurosurgeons, neurophysiologists, and other specialists trained in the assessment, treatment, and care of neurological conditions. Typically, after selecting a suitable subject and determining the target area for stimulation, precise placement of at least one electrode in the patient's sensory afferent area (such as the dorsolateral aspect of the spinal cord) is performed in an operating room setting, usually utilizing spinal cord imaging techniques. Following local anesthesia, the subject receiving the electrode implantation experiences minimal discomfort and may remain conscious during the procedure to communicate with the surgical team.

[0148] Some embodiments of this document employ an implant comprising one or more electrodes and / or neurostimulators implanted (e.g., fully or partially) in a subject. Further embodiments of this document employ an implant comprising one or more magnets or optical fibers and / or neurostimulators implanted in a subject.

[0149] Many types and styles of implants (e.g., implants including one or more electrodes for providing electrical stimulation) are available and well known to those skilled in the art. Any implant for specific stimulation of sensory neurons in a subject can be used in a particular embodiment. In some embodiments, more than one electrode is implanted, such as an electrode array. In other embodiments, a device comprising one or more electrodes is provided. Non-limiting examples include electrode arrays, penetrating microarrays (e.g., Utah and Michigan microarrays), microlead electrodes and arrays, neural cuffs, and paddle arrays.

[0150] In some embodiments, one or more electrodes are implanted at the dorsal root of one or more sensory neurons that innervate a body region of the subject with motor impairment. In some embodiments, one or more electrodes are implanted in the dorsolateral aspect of the spinal cord adjacent to the dorsal root of one or more sensory neurons innervating a body region of the subject with motor impairment. In some embodiments, one or more electrodes are implanted at the dorsal root ganglion of one or more sensory neurons that innervate a body region of the subject with motor impairment. In some embodiments, one or more electrodes are contained in a cuff surrounding or at least partially surrounding a peripheral nerve containing sensory neurons that innervate a body region of the subject with motor impairment due to SMA. In a further embodiment, one or more electrodes penetrate a peripheral nerve or dorsal root ganglion containing sensory neurons innervating a body region of the subject with motor impairment due to SMA.

[0151] In some embodiments, the disclosed methods utilize epidural electrical stimulation (EES) with a paddle electrode array targeting the dorsal lateral root, for example, as described in Rowald et al., 2022, Nat. Medicine, 28: 260-271 and Wagner et al., 2018, Nature, 563: 65-71, both of which are incorporated herein by reference in their entirety. Other non-limiting examples of paddle arrays and their uses are provided, for example, in US2009 / 0351221 and US2019 / 0366077, both of which are incorporated herein by reference.

[0152] In some implementations, a circuitry system is implanted to connect the neurostimulator to one or more electrodes. In certain implementations, the circuitry is either fully implanted (typically in a subcutaneous pouch within the subject's body) or partially implanted within the subject. The operative connection between the neurostimulator and one or more electrodes can be via one or more wires, but in certain implementations, any operative connection capable of transmitting stimulation signals from the circuitry system to the electrodes can be used.

[0153] Any suitable control system can be used with electrodes to apply electrical stimulation to a subject. Non-limiting examples of controllable neurostimulation systems are provided in US2020 / 0254260, US2020 / 0360693, US2020 / 0360697, US2020 / 0152078, US10,252,065, US10,799,702, US2021 / 0016093, and US2020 / 0391030, all of which are incorporated herein by reference. In addition, non-limiting examples of closed-loop neural stimulation systems are provided in US10,265,525, US10,279,167, US10,279,177, US10,391,309, US10,751,539, US10,981,004 and US2020 / 0147382, all of which are incorporated herein by reference.

[0154] In some embodiments, postoperative control of selective electrical stimulation is provided by an implantable neurostimulator, which can be externally or implanted, for example, subcutaneously (e.g., in the subject's chest or abdomen). In some embodiments, the disclosed method is influenced by the use of an implantable neurostimulator that controls stimulation (e.g., electrical stimulation via one or more implantable electrodes) according to predetermined parameters or parameters determined by feedback in a closed-loop system. In certain embodiments, one or more electrodes and the neurostimulator comprise an everyday assistive device for improving muscle weakness in the affected limb of a subject.

[0155] After the connection to the implantation, surgery, and electrode leads and neurostimulator is restored, the subject can be monitored and tested to establish parameters for the electrical stimulation based on the subject's motor impairment and motor injury, for example, by monitoring one or more motor outputs that provide measurements of the degree of motor injury and the subject's response to stimulation. In some implementations, electrical stimulation is delivered to sensory neurons in the subject via one or more implanted electrodes when the subject performs voluntary activities or tasks affected by the subject's motor injury; for example, forelimb tasks (e.g., reaching, grasping, picking up with the opposite thumb, gripping, and fine motor tasks involving precise finger movements) or lower limb tasks (e.g., walking, jumping, leg extension).

[0156] In some embodiments, a transcutaneous electrical stimulation system is used to apply electrical stimulation to sensory neurons in a subject. Non-limiting examples of transcutaneous stimulation systems are provided in US10,806,927, which is incorporated herein by reference. In such transcutaneous embodiments, the electrical stimulation may comprise an electrical pulse having an amplitude of about 10 µA to about 100 mA, a width between about 40 µs and about 2 ms, and a frequency of about 10 Hz to about 10000 Hz.

[0157] As described herein, the subject was also given a combination of SCS and SMA therapy. In some embodiments, the SMA therapy was sovalprevir, nusinersen, or lisporalen.

[0158] In some embodiments, the subject is receiving sovalprevir. Sovalprevir is also known as ZOLGENSMA® and is approved only for single-dose IV administration. Therefore, where the subject is given a combination of SCS and SMA therapy as described herein, and the SMA therapy is sovalprevir, a single dose of sovalprevir may be administered to the subject within 3, 6, 9, 12, 15, 18, 21, or 24 months prior to the initiation of SCS. For example, in some embodiments, sovalprevir is administered at least 3, 6, 9, 12, 15, 18, 21, or 24 months prior to the initiation of SCS. In some embodiments, sovalprevir is administered to the subject more than 24 months prior to the initiation of SCS, such as more than 2, 3, 4, 5, or 6 years prior to the initiation of SCS. In this context, SCS initiation involves the application of electrical stimulation; one or more electrodes must also be implanted, but this does not constitute the initiation or activation of the SCS. Furthermore, in some embodiments, SCS initiation includes the beginning or first instance of post-implantation electrical stimulation (e.g., excluding stimulation that may occur during implantation to locate the electrodes or map their stimulation to nerve roots and / or muscle groups). In some embodiments, SCS initiation includes the beginning or first instance of post-implantation electrical stimulation according to a stimulation protocol administered or supervised by a physician. References to SCS in these embodiments may also be described as the application of electrical stimulation to sensory neurons.

[0159] In some embodiments, the subject is receiving nusinersen. Nusinersen is also known as SPINAZA. TMIt is approved in the United States for intrathecal administration according to the recommended dosing regimen: 12 mg (5 mL) per dose, starting with four loading doses, the first three 14 days apart; the fourth loading dose 30 days after the third loading dose; and maintenance dosing every four months thereafter. Therefore, when SCS and nusinersen are administered to a subject in combination, SCS initiation can occur at any point during the nusinersen dosing regimen. Thus, in some embodiments, SCS is initiated between the first and second nusinersen loading doses, between the second and third nusinersen loading doses, between the third and fourth nusinersen loading doses, or after the fourth loading dose. Where SCS is initiated after the fourth nusinersen loading dose, SCS can be initiated at any point in time, that is, after the fourth loading dose but before the first maintenance dose, or between any subsequent maintenance doses. In this case, SCS initiation is the application of electrical stimulation; one or more electrodes must also be implanted, but this does not constitute initiation or activation of SCS. Furthermore, in some embodiments, initiating SCS includes the start or first instance of post-implantation electrical stimulation (e.g., excluding stimulation that may occur during implantation to position the electrodes or map their stimulation to nerve roots and / or muscle groups). In some embodiments, initiating SCS includes the start or first instance of post-implantation electrical stimulation according to a stimulation protocol administered or supervised by a physician. In some specific embodiments, when SCS is initiated, the subject receiving SCS in combination with nusinersen as described herein has completed four loading doses and is within a maintenance dosing regimen. In some embodiments, the subject received a first nusinersen dose (e.g., a first loading dose) at least 58 days prior to SCS initiation. In some embodiments, the subject received a first nusinersen dose (e.g., a first loading dose) at least 58 days, at least 3 months, at least 4 months, at least 6 months, at least 9 months, at least 12 months, at least 16 months, or at least 18 months prior to SCS initiation. In some embodiments, when SCS is initiated, the subject has received nusinersen therapy for at least 58 days, at least 3 months, at least 4 months, at least 6 months, at least 9 months, at least 12 months, at least 16 months, or at least 18 months. In still other embodiments, the subject has received nusinersen therapy for at least 2 years, at least 3 years, at least 4 years, at least 5 years, at least 6 years, or longer before initiating SCS. In some embodiments, the subject is on a nusinersen maintenance dosing regimen when SCS is initiated. References to SCS in these embodiments may also be described as the application of electrical stimulation to sensory neurons.

[0160] In some other embodiments, the subject is receiving lichepoprane. Lichepoprane, also known as EVRYSDI®, is approved for oral administration once daily according to the following regimens: 0.15 mg / kg body weight once daily for patients under two months of age; 0.2 mg / kg body weight once daily for patients between two months and two years of age; 0.25 mg / kg body weight once daily for patients two years of age and older weighing less than 20 kg; and 5 mg once daily for patients two years of age and older weighing more than 20 kg. Therefore, when SCS and lichepoprane are administered to the subject in combination, the initiation of SCS occurs after the subject has started receiving lichepoprane. In some embodiments, the subject begins receiving lichepoprane within 3, 6, 9, 12, 15, 18, 21, or 24 months prior to the initiation of SCS. In some embodiments, the subject has been given liscprolan therapy for more than 1 year, 2 years, more than 3 years, more than 4 years, more than 5 years, or more than 6 years prior to initiating the SCS. In this case, SCS initiation is the application of electrical stimulation; one or more electrodes must also be implanted, but this does not constitute the initiation or activation of the SCS. Furthermore, in some embodiments, SCS initiation includes the initiation or first instance of post-implantation electrical stimulation (e.g., excluding stimulation that may occur during implantation to locate the electrodes or map their stimulation to nerve roots and / or muscle groups). In some embodiments, SCS initiation includes the initiation or first instance of post-implantation electrical stimulation according to a stimulation protocol administered or supervised by a physician. References to SCS in these embodiments may also be described as the application of electrical stimulation to sensory neurons.

[0161] In certain implementations, the methods disclosed herein can be used in combination with programmed physical rehabilitation training to improve long-term outcomes.

[0162] Example

[0163] The following examples are provided to illustrate certain features of some implementations, but the scope of the claims should not be limited to those features.

[0164] Example 1

[0165] Biophysical model of spinal cord stimulation for SMA

[0166] This example provides a biophysical model illustrating the effectiveness of sensory neuron stimulation therapy for SMA patients, and a stimulation protocol for treating SMA patients (such as those with type 3 and type 4 SMA) by stimulating the dorsolateral aspect of the spinal cord.

[0167] Given the unique pathophysiology of SMA, applying SCS to SMA patients has yielded unexpected results. Although SMA patients typically have intact corticospinal tracts, unlike patients with spinal cord injury or stroke, many (if not all) of the MNs in SMA patients are nonfunctional or dead, especially in late-stage SMA patients, making them functionally inert. Therefore, SCS, which aims to increase excitatory input to the spinal MNs, is not expected to have any effect on SMA patients, as the MNs in SMA patients are already nonfunctional or dead. Of course, applying SCS to treat SMA while the MNs are still functioning is not expected to produce the effects observed in other conditions treated with SCS, such as spinal cord injury, stroke, and pain.

[0168] Surprisingly, however, as discussed below, significant immediate and end-of-study effects of SCS were unexpectedly observed in SMA patients treated according to this disclosure. Although experiments using an SMA mouse model have shown reduced presynaptic activity from sensory afferent fibers, this disclosure demonstrates that artificially increasing activity at sensory afferent fibers by SCS, with appropriate therapeutically effective amounts of SCS (such as in the dorsolateral position of the spinal cord), can excite MNs through the remaining excitatory connections and produce long-term enhancements to the affected synapses that help reverse the electrical changes in SMA-affected MNs. Furthermore, therapeutically effective amounts of SCS can also enhance the excitation rate of unaffected MNs, resulting in a more robust effect.

[0169] Network model of spinal cord circuit system

[0170] Healthy neuron model

[0171] Figure 1A shows a network model diagram in which MNs receive excitatory input from the corticospinal tract and spinal stimulations (SCS) (such as the dorsolateral SCS) by recruiting sensory afferent fibers. As shown in Figure 1A, a biophysical model was built using a group of healthy MNs (N=169 modified Hodgkin-Huxley neurons, McIntyre et al., 2002. J Neurophysiology 88 (4):1592–1604). Each MN receives excitatory input from the corticospinal tract (CST, N=110) and the SCS by recruiting sensory afferent fibers (N=60) (see Capogrosso et al., 2013. J Neuroscience. 33(49): 19326-40; Gerasimenko et al., 2006. J Neuroscience Methods 157(2): 253–63; Hofstoetter et al., 2015. J Neurophysiology 114(1): 400–410; Rattay et al., 2000. Spinal Cord 38(8): 473–89). The difference between the two sources of excitation is that the CST is modeled as a group of Poisson neurons, while the SCS has its own frequency and amplitude. To investigate motor recovery during SCS, the forces generated by the MN pool were quantified in arbitrary units (Fuglevand et al., 1993. J Neurophysiology, 70(6):2470-2488). Unlike CST, which represents voluntary input from the brain to the MN, SCS is controlled by the experimenter. Therefore, to improve voluntary movement, SCS should only enhance the MN activation rate when CST is active.

[0172] SMA neuron model

[0173] Figure 3A illustrates a model of SMA-affected neurons with various ion channels, where delayed rectified potassium channels (K-dr) are blocked. For healthy neuron models, the established approach to describing the membrane potential kinetics as a function of different ion channels is the Hodgkin-Huxley model. In this model, the membrane potential (V) is described by the following formula:

[0174]

[0175] Where C is the membrane capacitance, I is the current artificially injected into the neuron, and g is the conductance x of the ion channel x, which typically depends on the membrane potential and ion concentration. According to previous literature (Booth et al., 1997, J Neurophysiology 78 (6): 3371–85; McIntyre et al., 2002. J Neurophysiology 88 (4): 1592–1604; Moraud et al., 2016. Neuron 89 (4): 814–28), the following ion channels are included: delayed rectified sodium (Na) and potassium (K-dr), N-like calcium (Ca-N), L-like calcium (Ca-L), and calcium-dependent potassium (K(Ca)), as shown in Figure 3A. The model was implemented in a neuronal stimulation environment designed to model individual neurons and neuronal networks, referred to in this paper as NEURON (Hines and Carneval. 1997. Neural Computation 9(6): 1179–1209).

[0176] Figure 3B illustrates an MN model with various ion channels, including a specific delayed-rectification potassium channel (Kv2.1). Without being bound by any particular theory, the loss of SMA-induced sensory afferent input (e.g., Ia) can alter the Kv2.1 channel of the MN into a dysfunctional state with increased refractory period (e.g., slower excitation rate) and / or increased input resistance. Furthermore, the defect in MN function can be restored by increasing sensory afferent input into the SMA-affected MN (e.g., via SCS), which reduces the MN's input resistance. Additionally, SCS can instantaneously increase sensory afferent input, thereby increasing the excitation rate of the SMA-affected MN. Over time, SCS can salvage MN function by altering the Kv2.1 channel of the MN to its healthy, functional state.

[0177] SCS increases the excitability of MN without producing involuntary movements.

[0178] Figures 1B through 1G illustrate various models of SCS enhancement of MN output. In all figures 1D through 1G, the “amplitude” unit is the percentage of sensory afferent fibers recruited by the SCS. Figure 1B plots the membrane potential (mV) of MN stimulated at a frequency of 69 Hz and an amplitude that recruits 30% of sensory afferent fibers. Note that the parameters shown in Figure 1B correspond to the point marked “1” in Figure 1D. The black dashed line represents the resting potential of the MN membrane potential, while the gray dashed line represents the MN spike threshold. With appropriate parameters, SCS can increase the excitability of MN without generating an action potential. Figure 1C plots the membrane potential (mV) of MN stimulated at a frequency of 69 Hz and an amplitude that recruits 80% of sensory afferent fibers. Note that the parameters shown in Figure 1C correspond to the point marked “2” in Figure 1D. Figure 1D is a gradient plot showing the MN firing rate as a function of SCS parameters in the absence of input from the corticospinal tract (CST), indicating that the SCS itself generates involuntary motion (MN firing rate > 8 Hz). On a scale of 0 to 30 spikes / s, the darker shaded areas in each of Figures 1D through 1F show more spikes per second. Figure 1E is a gradient plot showing the MN firing rate as a function of SCS parameters with input from the CST. Figure 1F is a gradient plot showing the MN firing rate generated by a combination of SCS parameters that produces only voluntary motion normalized from the MN firing rate without SCS. Figure 1G is a gradient plot showing how the SCS amplifies the force generated by the MN swarm. The “arbitrary unit” scale in Figures 1F and 1G indicates how many times greater the firing rate with SCS is compared to the firing rate without SCS. The upper limit of the "arbitrary unit" scale is 2.2 times. Therefore, these figures show that the MN excitation rate with SCS is 2.2 times greater than without it.

[0179] To investigate the effect of continuous SCS on the firing rate of MN, a range of stimulation parameters were explored. Generally, the firing rate of MN increases as a function of SCS frequency and amplitude, as shown in Figure 1D. However, a local maximum was determined at 25 Hz, which is related to the time constant of the modified Hodgkin-Huxley neuron model (McIntyre et al., 2002. J Neurophysiology 88 (4):1592–1604). SCS was able to increase the firing rate of MN above the minimum firing rate required to produce motion (> 8 Hz) (Monster and Chan, 1977. J Neurophysiology 40 (6):1432–43), as shown in Figures 1C and 1D. Any combination of SCS parameters that produced motion (i.e., involuntary motion) without CST involvement was discarded for the purpose of restoring voluntary motion. However, SCS can also increase MN excitability (i.e., depolarize the membrane potential) without producing involuntary motion (i.e., MN excitation rate < 8 Hz), as shown in Figures 1B and 1D. This increase in MN excitability represents a mechanism for enhancing CST input.

[0180] SCS enhances supraspinous input, thereby increasing MN activation rate.

[0181] Healthy neuron model

[0182] After demonstrating that SCS can increase the excitability of MN in a healthy model, it was evaluated whether SCS could also enhance CST input to activate MN and generate force. For this evaluation, the input from CST was fixed to produce a relatively low excitation rate (9.3 Hz) in MN. The MN excitation rate was calculated while systematically varying the SCS parameters (frequency and amplitude). For a range of these parameters, SCS enhanced the input from CST to increase the MN excitation rate without generating involuntary motion, as shown in Figures 1E and 1F. The force generated by the enhanced excitation rate of MN with SCS was 2.2 times stronger than that generated by the same CST input without SCS, as shown in Figure 1G.

[0183] Figures 2A through 2C illustrate graphs describing the force enhancement during simulated voluntary brain input. Figure 2A plots the following network activity parameters: SCS amplitude, corticospinal tract (CST) activation rate (Hz), MN activation rate (Hz), and force normalized by the applied average force. For the network activity in Figure 2A, no SCS stimulation was applied, and a 22 Hz CST input was applied. Figure 2B plots the network activity with SCS applied in the voluntary motor region. Note that the parameters shown in Figure 2B correspond to point “3” in Figure 1E. The MN activation rate, and therefore the force, is enhanced relative to the SCS off state. Figure 2C plots the network activity with SCS applied in the involuntary motor region. Note that the parameters shown in Figure 2C correspond to point “4” in Figure 1E. The MN activation rate is high in both phases (with and without input from CST).

[0184] To further understand the enhancement of CST input driven by SCS, a vibrational force task was modeled, where CST input arrived at MN in a periodic manner, as shown in Figures 2A to 2C. Differences between voluntary and involuntary motion regions were assessed. In the voluntary motion region, SCS increased the excitability of MN, resulting in a higher excitation rate observed compared to the absence of SCS. However, SCS did not increase the excitation rate of MN during periods without CST input, as shown in Figures 2A and 2B. In the involuntary motion region, SCS increased the excitation rate throughout the experiment and during periods without CST input, as shown in Figure 2C. These results collectively suggest that, within a healthy spinal cord biophysical model, CST input can be enhanced to produce an enhanced MN excitation rate, thereby generating stronger forces.

[0185] SMA neuron model

[0186] A series of experiments using the SMA mouse model have shown that SMA-affected nuclei (MNs) exhibit dysfunctional electrical properties (Mentis et al., 2011. Neuron 69 (3): 453–67; Fletcher et al., 2017. Nat Neuroscience 20 (7): 905–16), due to reduced synaptic activity from sensory afferent fibers and blockage of delayed rectifier potassium channels (Fletcher et al., 2017. Nat Neuroscience 20 (7): 905–16; Simon et al., J Neuroscience. 41(2): 376-389, 2021). As shown in Figure 3A, downregulation of K-dr channels reduces the excitability of MNs. Therefore, to model SMA-affected MNs, the synaptic weights (i.e., synaptic strength) from sensory afferent fibers and the conductance of delayed rectifier potassium channels were reduced, as shown in Figure 3A. This neuron model can be validated by reproducing the following three dysfunctional electrical properties of an MN affected by SMA:

[0187] (1) High input resistance: In the NEURON simulation environment, designed for modeling individual neurons and neural networks, current can be easily injected directly into MN and the input resistance can be calculated as the slope of a voltage-current function. Blocking potassium channels reduces potassium ion outflow, thereby increasing the input resistance.

[0188] (2) Reduced base strength: As in (1), current is injected into MN, from which the minimum input current required to generate an action potential can be calculated. Similarly, reducing the outflow of potassium ions will depolarize the membrane potential more quickly, thereby reducing the injection current required to trigger an action potential.

[0189] (3) Low excitation rate induced by current higher than that required to induce repetitive excitation: An artificial current higher than the repetitive excitation rate threshold of MN affected by SMA was injected to test whether the blockage of potassium channels was sufficient to reduce the excitation rate. After the action potential, potassium channels open, causing the membrane potential to repolarize. When these channels are blocked, the repolarization phase will be slower than in healthy MN, thus reducing the output excitation rate (Fletcher et al., 2017. Nat Neuroscience 20 (7): 905–16).

[0190] Example 2

[0191] Spinal cord stimulation therapy for SMA

[0192] This example describes a specific method for treating SMA in patients by applying a therapeutically effective amount of electrical stimulation to the dorsolateral spinal cord, which contains sensory neurons innervating body regions of a patient with motor impairment due to SMA. While specific methods and protocols are provided, those skilled in the art will understand that variations can be made without significantly affecting the treatment. Three SMA patients were identified and enrolled in this spinal cord stimulation trial. One patient (“SMA01”, described in more detail below) was not receiving concurrent SMA therapy at the time of enrollment in the SCS trial. Two patients (SMA02 and SMA03, described in further detail below) were receiving the SMA therapy nusinersen at the time of enrollment in the SCS trial.

[0193] Three human patients with type 3 SMA exhibiting quantifiable leg motor deficits were selected for treatment. The first patient (hereinafter referred to as "SMA01") was a 22-year-old male with an initial Hammersmith Functional Motor Scale Extended (HFMSE) motor ability score of 60 (out of 66) and was not receiving SMA therapy. The second patient (hereinafter referred to as "SMA02") was a 55-year-old male with lower motor ability than SMA01 (HFMSE score of 38 (out of 66)) and was receiving SMA therapy (nusinersen). The third patient (hereinafter referred to as "SMA03") was a 30-year-old male with motor ability between SMA01 and SMA02 (HFMSE score of 49 (out of 66)) and was also receiving SMA therapy (nusinersen). Percutaneous, bilateral, linear spinal cord leads were implanted near the lumbar spinal cord in all three patients for up to 29 days (four weeks).

[0194] To quantify the immediate improvement in movement driven by SCS, the maximum torque generated at different joints, such as the hip, knee, and ankle, during isometric motion was measured. These measurements were performed using the HUMAC® Norm system. This system allows the patient to be positioned in different locations to assess the maximum torque at these joints (Figures 4A to 4C). Figure 4A shows hip extension, Figure 4B shows knee extension, and Figure 4C shows ankle extension.

[0195] During the assessment, patients progressively contract from a resting state to maximal force, receiving real-time visual feedback on torque during this process. The same measurement is repeated to systematically explore different SCS parameters, including those without SCS, to determine the most effective parameters for reducing motor injury in patients. As an example, electrical stimulation can be applied with electrical pulses having an amplitude of approximately 10 µA to approximately 50 mA, a width between approximately 40 µs and approximately 2 ms, and a frequency of approximately 10 Hz to approximately 2000 Hz. Furthermore, surface electromyography (EMG) can be used to record electrical activity generated by the agonist and antagonist muscles of each joint. Applying appropriate SCS parameters to provide a therapeutically effective amount of electrical stimulation is expected to increase maximal torque and EMG activity.

[0196] This example aims to measure the immediate, end-of-study, and long-term effects of SCS on SMA, including various clinical outcomes. First, the immediate effect of SCS on SMA is measured by turning stimulation on and off within the same treatment session and by measuring the SCS effect that exists only during stimulation and disappears when stimulation is turned off. As used herein, “immediate” refers to an effect measured during the four-week study period and involves the use of SCS. Second, the end-of-study effect of SCS on SMA is measured by comparing patient performance in the absence of stimulation across different treatment sessions. As used herein, “end-of-study” refers to an effect measured approximately one week before or after the end of the four-week study, approximately at the time of SCS electrode removal. Third, the long-term effect of SCS on SMA is measured by following up with patients several weeks after the end of the study and after stimulation removal. Specifically, as used herein, “long-term” refers to an effect measured more than 50 days after electrode removal and involves changes in motor ability over time with discontinuous SCS application. Immediate and long-term effects of SCS on SMA patients were observed. Contrary to expectations in patients affected by SMA, the magnitude of the immediate effect was similar to that observed in patients with stroke and spinal cord injury. For subjects with spinal cord injury and / or stroke, the immediate effect of SCS was superior to the long-term effect. Conversely, for SMA subjects, the long-term effect of SCS was superior to the immediate effect. Furthermore, the magnitude of the long-term effect observed in nonfunctional MN patients during a trial of only 4 weeks was unexpected; these patients experienced muscle strength improvements exceeding the levels expected in normally SMA-affected patients. These improvements in muscle strength were too significant to be attributed solely to exercise. For example, SMA01's left hip flexion more than doubled, even though this patient did not perform any hip strength training other than walking during the study. SMA01's motor level remained unchanged relative to pre-study levels. These changes are reflected in improvements in clinical outcome tests, such as the manual muscle test, the Hammersmith Functional Motor Scale Extended (HFMSE), the revised Hammersmith Scale (RHS), and the 6-minute walk test for SMA01 and SMA02. Furthermore, the data did not indicate a plateau, suggesting that longer use of the SCS may lead to even greater improvements. Because SMA02 was older and had more severe motor impairment than SMA01, his improvement in muscle strength was smaller than SMA01's, but consistent with the results. However, compared to SMA01, who had only mild gait deficits, SMA02 showed more significant gait improvements at the end of the study and immediately thereafter.

[0197] Furthermore, for SMA01, SCS therapy increased leg joint torque (up to +180%) and MN activation rate during a 4-week treatment course, indicating that SCS is improving MN function, with no side effects reported. These results suggest that SCS can potentially improve the quality of life of patients with severe and mild SMA by improving muscle strength and gait. The degree of improvement observed in SMA patients within such a short timeframe is unexpected. This degree of muscle strength improvement observed in such a short timeframe may indicate a disease-modifying effect. Without being bound by any particular theory, the improved strength is likely driven by salvaged MN function in response to increased afferent input to the patient's hip flexors and knee extensors, driven by SCS. Analysis of spinal reflexes and single MN activation rates obtained using HD-EMG recordings was used to confirm this conclusion. Furthermore, fMRI analysis showed increased activity in the pre-implantation spinal circuits compared to post-removal. This increase may indicate that stimulation salvages MN function by artificially increasing afferent input.

[0198] Initial configuration and optimization

[0199] Before electrode implantation, a patient's initial performance can be measured. These measurements can be performed using the HUMAC® Norm system. This system allows the patient to be positioned in different locations to assess maximum torque at different joints. Figures 5A and 5B illustrate isokinetics (e.g., HUMAC® Norm isokinetics) configured to test hip flexion and knee extension in human patients, respectively. Specifically, the maximum torque generated by the patient during knee, hip, and ankle extension and / or flexion can be measured.

[0200] Bilateral linear SCS leads were implanted into the epidural space between the T11 and L1 vertebrae. In one instance, to target the right leg muscles, bipolar stimulation of the spinal cord was used at the two cephalic contacts of the right lead. The SCS parameters in this instance were 2 mA, 40 Hz, and a pulse width of 400 µs. In another instance, to target the left leg muscles, tripolar stimulation was used. The SCS parameters in this instance were 3.7 mA, 40 Hz, and a pulse width of 400 µs.

[0201] Figure 32 shows a table of optimal current values ​​and wire configurations for SMA01, SMA02, and SMA03. Electrode names are coded from 1 to 8, with letters indicating whether it is a left or right electrode. For example, 1L represents the first contact of the left array. 7R represents the second-to-last contact of the right wire. When indicating the configuration, the first contact is the cathode, and the contacts after "vs" are the anodes. For example, "1L vs 1R 5L" means that 1L is selected as the cathode, while 1R and 5L are both selected as anodes.

[0202] According to the subjects, effective SCS treatment administered via implanted leads did not cause significant discomfort or pain. SCS produces tingling sensations and other types of sensory phenomena, but the stimulation intensity required to improve motor function remains within the range of non-painful sensations. As shown in Figure 33, SMA01, SMA02, and SMA03 were asked to provide a rating from 1 to 10 for each stimulation configuration (where higher numbers indicate greater discomfort). In the optimal configuration, the maximum discomfort rating provided by any subject was 2 out of 10. The maximum discomfort rating provided in the suboptimal configuration was 5 out of 10.

[0203] SCS can be applied to target muscles affected by SMA. In this case, SMA01 was found to have significant deficiencies in the knee extensors and hip flexors, consistent with its type 3 diagnosis. Furthermore, SMA01 showed slightly more deficiencies in the left leg. Therefore, the stimulator can be programmed to selectively target these muscles. In this case, all experiments were conducted over a period of 4 weeks and a total of 19 treatment sessions. Experiments were performed daily, 5 days a week, until the date the electrodes were removed. Each treatment session lasted 4 hours, including approximately 2 to 3 hours of task time, with an estimated 2 hours of active stimulation dose per day during these sessions.

[0204] The placement of SCS can be optimized and fine-tuned by stimulating various contact points, measuring electrical activity generated by muscles (e.g., agonist and antagonist muscles of each joint), and evaluating the measurements. Appropriate SCS parameters are then used to measure maximum torque and EMG activity to determine the effective amount of electrical stimulation for treatment. In this example, electrode placement was determined during surgery by stimulating each contact point and recording EMG signals from the muscles from the trunk to the ankle. Stimulation was repeated until the locations where the electrodes activated the hip muscles with the most cephalic contact and the calf muscles with the most caudal contact were identified.

[0205] These implants can be used to configure spinal cord electrical stimulation programs to achieve control over the degree of extension and flexion of each leg during movement. The protocol utilizes real-time processing of gait kinematics and motor performance and can be configured within days. Once configured, stimulation bursts are delivered to specific spinal cord locations at precise timing to reproduce the natural spatiotemporal activation of the MN during movement. These protocols can also be readily adapted for safe implantation of systems near the spinal cord and for experimentation involving real-time motor feedback and closed-loop controllers, as discussed below.

[0206] Electrode placement during surgery can be adjusted to account for postoperative electrode movement. This postoperative movement can be variable and difficult to avoid with non-permanent implants. For example, the electrode may move caudally or shift medially. Figure 6 shows a comparison between the electrode position during surgery (black) and the postoperative electrode position (white) in a subject. In this particular instance, the change in position does not prevent stimulation of the correct muscle group. Based on the predicted postoperative movement of the electrode, it can be implanted in an adjusted position during surgery so that, postoperatively, the electrode will move to a predefined optimal position. More details on devices and surgical procedures that can be used to obtain chronic EMG recordings from leg muscles and implant targeted spinal cord stimulation systems can be found in Capogrosso et al., 2018. Nature Protocols 13.2031-2061, which is incorporated herein by reference in its entirety.

[0207] Observed immediate effects

[0208] The immediate effects of SCS are measured based on maximal voluntary contraction, hip flexion during movement, balance, transition from seated to standing, maximum speed, and gait on the ground. Each measurement is discussed below. It should be understood that different indicators may be used depending on the patient's target muscles or conditions.

[0209] Maximum Spontaneous Contraction: To assess maximum voluntary contraction, SMA01 was required to produce its maximum voluntary isometric contraction (MVC) during knee extension with and without SCS, lasting 5 seconds. After multiple repetitions of knee extension, SMA01 showed obvious signs of fatigue. At this point, the immediate effect of SCS on the patient's maximum voluntary contraction (MVC) during fatigued knee extension was tested. Figures 7A through 7C show various torque measurements over time. Figure 7A shows the single-shot trajectory of the torque produced by SMA01 during repetitions of maximum voluntary contraction with and without stimulation (see element 704). In Figure 7B, each point corresponds to the average torque produced during a single test with and without stimulation. In Figure 7C, each point corresponds to the maximum torque produced during a single test with and without stimulation. In Figures 7B and 7C, square markers represent the mean between repetitions, and error bars correspond to the standard error of the mean. As shown in the figure, MVC was significantly higher on days 12 and 27 during SCS stimulation.

[0210] Similarly, the SMA02 was required to generate its MVC during knee extension for 2 seconds with and without SCS. Because the SMA02 can only generate very small forces, the increase in force was not statistically significant regardless of whether the stimulation was on or off, or between different stimulation parameters, as shown in Figures 7D and 7E. Figures 7D and 7E depict the torque measurements obtained at baseline during knee extension using the SMA02 with two different stimulation contacts, 1L and 4L. As shown, the average torque of contact 1L is higher than the baseline, but the average torque of contact 4L is not. The total peak torque of both 1L and 4L is high. The figures illustrate that contact configuration affects torque output.

[0211] To obtain more data on the role of SCS in the immediate increase of muscle strength (measured by torque generated by MVC), SMA03 was required to generate its MVC during knee flexion with and without SCS. Figures 28A and 28B show the various torque measurements during trials on different days. Each point corresponds to the average / maximum torque generated during a single trial, square markers indicate the average across trials on the same day, and error bars correspond to the standard error of the average. Baseline values ​​of knee flexion capacity of SMA03 without SCS were measured before implantation (e.g., on days -9, -4, and -3). After implantation (e.g., on days 6 and 7), knee flexion torque generated by SMA03 with and without stimulation was measured. Figure 28A shows the average torque generated during trials with and without stimulation. The average torque generated when stimulation was applied was greater than when stimulation was off. Similarly, Figure 28B shows the maximum torque generated during the trial with and without stimulation, depicting that the maximum torque with stimulation on is greater than the maximum torque with stimulation off. In both figures, the torque with stimulation is greater than the baseline torque before implantation and the torque without stimulation. These figures demonstrate that stimulation applied via the SCS immediately increases muscle strength beyond the patient's normal capacity without stimulation.

[0212] Hip flexion during exercise: SMA01 was instructed to achieve maximum hip flexion by raising their knees as high as possible while their body weight was supported by a treadmill. Stimulation cycles alternated on and off every 20 seconds as the patient walked. No visual feedback on their legs was provided to SMA01 during the task. To measure changes in stride height, tracking markers were placed on the ankle, toes, and metatarsals of each foot. Machine learning models (e.g., deep neural networks) could be trained to track the markers. Figures 8A and 8B illustrate how spinal stimulation increased maximum hip flexion during exercise. Specifically, Figure 8A shows the trajectories of the ankle markers during exercise with and without stimulation (see element 802) and with stimulation (see element 804). In Figure 8B, the dots represent the height of each step calculated as the difference between the minimum and maximum values ​​for each trajectory in Figure 8A. Square markers represent inter-step averages, and error bars correspond to the standard error of the average. As shown in Figures 8A and 8B, SCS provides an immediate increase in maximum hip flexion during movement of SMA01, which translates into higher stride height.

[0213] Balance: SMA01 was instructed to walk heel-to-toe while looking directly at a beam of light that narrowed in distance, without receiving visual feedback from its feet. During the first session, SMA01 performed worse with stimulation on and walked shorter distances. The patient reported that the stimulation disrupted its balance as precise control of its legs became more difficult.

[0214] However, when SMA01's balance was retested during the second (one week after the first) and third (one week after the second) treatment cycles, it was found that the patient had learned to control the stimulation and improved his balance, resulting in similar distances being produced when stimulation was on and off. Figures 9A and 9B show that spinal cord stimulation only temporarily disrupted the patient's balance. In Figure 9A, each point represents the walking distance of SMA01 in the narrow beam test with and without stimulation (see element 902) and with stimulation (see element 904). Squares represent the mean, and error bars represent the standard error of the mean between repetitions. Figure 9B is an image of SMA01 walking on the narrow beam.

[0215] Sit-to-stand transition: Instruct SMA01 to stand from a position with one knee on the ground and the other foot on the ground. Test different knee heights until the maximum height at which the patient cannot stand is determined. Stimulation is then applied. When the right knee is on the ground, SMA01 is able to consistently achieve a standing position.

[0216] The patient was also asked to stand from a seated position on a box 46 cm above the ground. Without stimulation, SMA01 was able to compensate by standing with its legs exaggeratedly spread apart. The patient was then instructed to continue attempting to stand, bringing its feet together until the distance between its feet reached a point where it could no longer stand. Stimulation was then applied to the patient with its feet in the same position (i.e., separated to a distance where it could no longer stand), and SMA01 was able to stand from this position consistently.

[0217] Maximum speed: SMA01 was instructed to run on a treadmill, with the speed gradually increased every 30 seconds until it reported reaching its maximum speed. Figure 10 shows that SCS (see element 1004) robustly increased the patient's maximum speed relative to when no SCS was applied (see element 1002).

[0218] Ground walking gait: SMA01 and SMA02 were asked to walk back at a self-selected speed with and without stimulation. The Vicon® system was used to record the position and orientation of reflex markers attached to specific anatomical landmarks, from which joint angles, velocities, and accelerations were reconstructed. Principal component analysis (PCA) was performed to assess the kinematic variables that could explain most of the variance between the tests with and without SCS. For SMA01, the variable that explained most of the variance was related to the velocity of knee flexion / extension during the swing phase, indicating that knee flexion was faster with stimulation, as shown in Figure 19B. Stimulation was found to increase gait velocity and decrease stride duration, as shown in Figures 20C and 20D.

[0219] PCA analysis of SMA01 showed that stimulation reduced knee rotation during the swing phase, indicating a reduction in compensatory strategies during gait. Less knee external rotation was observed during the stimulus-on test, which may also indicate a reduction in compensatory strategies during gait. Figures 19A and 19B show the PCA results for SMA01. Figure 19A shows the principal component (PC) space consisting of the first three PCs. The difference between the stimulus-on and stimulus-off tests is evident along the direction of the third PC. Overall, the stimulus-on test had a lower third PC value than the PC-off test. Figure 19B shows gait characteristics more strongly correlated with the third PC. Figures 19C and 19D show similar PCA results for SMA02. Figures 20A through 20D show short-term improvements in several gait quality variables for SMA01. These figures show that, for both its right and left sides, with stimulation, stride length increased (Figure 20A), stride height increased (Figure 20B), and stride duration decreased (Figure 20C). Figure 20D shows that the gait time of SMA01 is improved, i.e. reduced, when stimulated. Figures 20E to 20H show short-term improvements in several gait quality variables of SMA02, which is similar to SMA01, when stimulated.

[0220] PCA analysis of SMA02 showed that stimulation improved different gait patterns:

[0221] 1) Stimulation increased the range of hip abduction / adduction and knee flexion / extension (as shown in Figure 19D), as well as the maximum hip flexion angle (as shown in Figures 21C and 21D). Therefore, SMA02 was able to take longer and higher strides compared to the absence of stimulation (as shown in Figures 20E and 20F).

[0222] 2) Stimulation also increased the maximum dorsiflexion angle of the ankle during the standing phase (as shown in Figure 19D), improved foot lift and toe lift (as shown in Figures 21C and 21D).

[0223] Furthermore, the methods disclosed herein were found to reduce compensatory strategies in patients with SMA. For example, SMA patients tend to compensate for weaker quadriceps during the swing phase by plantarflexing their feet to increase hip flexion. Both SMA01 and SMA02 reduced this compensatory strategy upon stimulation: they exhibited reduced plantarflexion and increased hip flexion. Therefore, the results suggest that SCS has the potential to generate kinetic-dynamic changes that can immediately alleviate gait deficits during ground walking.

[0224] Observed study end effect

[0225] In this example, the effect of SCS at the end of the study was measured based on hip flexion, maximal voluntary contraction, ground walking gait, and functional magnetic resonance imaging of the spinal cord during exercise. These measurements were performed before or shortly after electrode removal in the patient (i.e., within one week) and illustrate the effect of SCS at the end of the four-week experiment. Each measurement is discussed below. It should be understood that different indicators may be used depending on one or more targeted muscles and conditions in the patient.

[0226] No serious adverse events (such as falls) related to SCS were observed during the four-week trial. Injuries during falls were avoided due to risk mitigation strategies employed in the trial (such as straps, harnesses, and / or the presence of a physical therapist during physical activities).

[0227] Hip flexion during exercise: In week 4, SMA01 was asked to walk on a treadmill while raising their knees as high as possible. Figures 11A and 11B show the effect of SCS on hip flexion at the end of the four-week trial. Figure 11A shows the ankle marker tracks during exercise, comparing the tracks in week 1 without stimulation (see element 1102) with those in week 4 without stimulation (see element 1104). In Figure 11B, the points are the height of each step calculated as the difference between the minimum and maximum values ​​for each track in Figure 11A. The squares are the inter-step mean and the standard error of the mean. By comparing weeks 1 and 4, a significant increase in maximum hip flexion during exercise was observed in SMA01, even without stimulation, indicating the effect of the SCS intervention at the end of the study. Without being bound by any particular theory, applying electrical stimulation to patients over time may lead to ion channel remodeling on the MN membrane and a sustained increase in the probability of spinal cord MN activation rate, which can improve motor function even in the absence of stimulation.

[0228] Maximum voluntary contraction: At the start of each treatment session using the isokinetic machine, the MVC of SMA01 and SMA02 was measured as torque (in Newton-meters (Nm)) during unstimulated knee extension and / or hip flexion. Patients had an MVC of approximately 20 Nm during knee extension, while healthy young adults had an MVC greater than 100 Nm. SMA01 was asked to generate its maximum torque in these joints, repeated 6 times for 5 seconds each time. To prevent early fatigue, SMA02 was asked to generate its maximum torque in these joints, repeated 6 times for 2 seconds each time. Knee extension was tested twice weekly, and hip flexion was tested before implantation, at week 1, week 3, and after removal. Generally, a significant increase in MVC was observed in all movements starting from week 2.

[0229] Regarding right knee extension, a sustained increase in both maximum and mean torque was observed from day 18 until the end of the study, when the SCS was closed. The final increase from pre-implantation to the end of the study was +43.5%. Figures 12A through 12C illustrate the improvement in right knee extension with SMA01 at the end of the study. Figure 12A shows the torque trajectory for 6 repetitions in each treatment cycle. In Figures 12B through 12C, each point represents the mean torque for each 5-second repetition. The squares represent the mean of the mean torque between repetitions and the standard error of the mean. As shown, the effect appears linear, and there is no evidence of a plateau by week 4. From day 18 until the end of the study, when the SCS was closed, SMA01 experienced a sustained increase in both maximum and mean right knee extension torque. For SMA01, the final increase from pre-implantation to the end of the study was +43.5%.

[0230] The MVC of SMA02 during knee extension was less than 1 Nm, while that of SMA01 was greater than 20 Nm, and the MVC of healthy young adults was greater than 100 Nm. Therefore, knee extension of SMA02 was more restricted than that of SMA01. Figures 12D to 12F show the improvement in right knee extension of SMA02 at the end of the study. For SMA02, the mean torque increased by +33.3% from pre-implantation to the end of the study (as shown in Figure 12E). However, no significant difference was observed in peak torque (as shown in Figure 12F).

[0231] A similar sustained increase in left knee extension was observed from day 18 until the end of the four-week experiment, even in the leg where SMA01 was more severely affected. During the four weeks of the SCS experiment, the left knee extension results were largely consistent with those of the right knee, as no increase was observed before day 18, followed by a sustained increase thereafter. The final increase from day 5 to the end of the study was +65.1%. Figures 13A through 13C illustrate the improvement in left knee extension at the end of the study. Figure 13A shows the torque trajectory for 6 repetitions in each treatment cycle. In Figures 13B through 13C, each point represents the average torque for each 5-second repetition. The squares represent the mean of the average torque between repetitions and the standard error of the mean.

[0232] The improvement time of SMA01 in right and left hip flexion was consistent with the results of knee extension, with increases observed in both from day 18 until the end of the four-week trial for hip flexion. For SMA01, the final increase from pre-implantation to post-removal was +65.1% on the right and +179.7% on the left. Figures 14A to 14C show the improvement in right hip flexion at the end of the study. Figure 14A shows the torque trajectory for 6 repetitions in each treatment cycle. In Figures 14B to 14C, each point represents the mean torque for each 5-second repetition. The squares represent the mean of the mean torque between repetitions and the standard error of the mean. Figures 15A to 15C show the improvement in left hip flexion with SMA01 at the end of the study. Figure 15A shows the torque trajectory for 6 repetitions in each treatment cycle. In Figures 15B to 15C, each point represents the mean torque for each 5-second repetition. The squares represent the mean of the mean torque between repetitions and the standard error of the mean.

[0233] The right hip extension of SMA02 increased by +21.7% from pre-implantation to post-removal. Figures 15D through 15F show the improvement in right hip extension of SMA02 at the end of the study. Figure 15D shows the torque trajectory for 6 repetitions in each treatment cycle. In Figures 15E through 15F, each point represents the mean torque for each 5-second repetition. The squares represent the mean of the mean torque between repetitions and the standard error of the mean.

[0234] Due to these improvements in hip flexion and knee extension, the patient's overall range of motion was significantly greater at the end of the experiment than before. The improvements in range of motion were most pronounced in hip flexion and whole-body movement. Without being bound by any particular theory, applying electrical stimulation to sensory neurons can directly recruit monosynaptic and polysynaptic excitatory pathways in the spinal cord, which in turn increases the membrane potential and activation rate probability of spinal cord MNs innervating body regions of patients with motor impairment due to SMA. This pathway recruitment can increase neural plasticity, thereby enabling patients to improve motor function.

[0235] To obtain more data on the role of SCS in increasing muscle strength (measured by torque generated by MVC) during the study, SMA03 was required to generate its MVC multiple times during knee flexion during the four-week study period. Figures 27A to 27B extend the dataset of Figures 28A to 28B, showing the various torques measured by SMA03 in trials on different days. Each point corresponds to the mean / maximum torque generated during a single trial, square markers indicate the mean between trials on the same day, and error bars correspond to the standard error of the mean. Patients' MVC values ​​showed a clear upward trend throughout the study (e.g., from day 6 to day 26) relative to the pre-implantation baseline values ​​of SMA03 knee flexion capacity (e.g., values ​​on days -9, -4, and -3). Furthermore, knee flexion torque was measured with and without stimulation during the study. The torque generated when stimulation was applied (indicated by the shallower dots of "Stim ON") was greater than the torque generated when stimulation was off (indicated by the deeper dots of "Stim OFF"). Figure 27A shows the average increase in torque generated during the study. Similarly, Figure 27B shows the maximum increase in torque generated during the study. In both figures, the torque measured at the end of the study (e.g., day 26), with or without stimulation, was significantly greater than the baseline torque before implantation. These figures demonstrate that stimulation via SCS gradually increased muscle strength beyond the patient's normal capacity during the study. Even without active SCS application at the end of the study, the muscle strength of SMA03 was higher than the baseline value at the start of the study.

[0236] Figure 34 uses a network diagram to illustrate the percentage increase in absolute torque at all joints during the studies in SMA01 and SMA03. (The original data used to generate Figure 2 can be found in the “Supplementary Data” section corresponding to Figures 35 and 36.) Significant improvements were observed in both hip flexors and hip extensors in both participants when comparing pre- and post-study results. At a follow-up of six weeks after the end of the study, there was a slight increase in hip torque, while other torques returned to pre-study levels. SCS was not applied during any of the periods during which these results were collected.

[0237] Despite significant differences in disease severity, both subjects showed similar results, with a substantial increase in isometric torque, primarily observed in the hip, with a change of up to +200%. The magnitude of these improvements in such a short timeframe suggests a change in spinal cord MN levels, specifically in muscle recruitment efficiency. This was particularly true for the hip muscles, which did not receive weekly strength training. Hip torque was assessed only three times: before, during, and after the study, with minimal strength training provided. In contrast, knee muscles were tested multiple times weekly, providing effective knee strength training. Therefore, the improvement in hip function cannot be explained by strength training, but it indicates the greatest improvement from SCS treatment. These findings correlate with the phenotype of the Delta7 mouse model described in a study from Mentis et al., 2011. Neuron 69 (3): 453–67, which showed that hip muscles are more susceptible to SMA than ankle muscles. However, no other study (whether treating SMA or any other disease) has demonstrated such a large improvement (+200%) in leg muscle strength after four weeks. Strength training alone cannot explain these improvements, because it is impossible to “train” participants to double their muscle strength in four weeks.

[0238] Range of Motion (ROM): The ROM of the hip and knee during ground movement for SMA01, SMA02, and SMA03 was calculated after the study. Here, ROM is defined as (maximum angle - minimum angle). This calculation specifically refers to the angle during the swing. Figures 37A and 37B provide gait cycle curves of joint angles and ROM of hip and knee movement for SMA01, SMA02, and SMA03 at different weeks with SCS closed. Figure 38 presents a table of hip and knee ROM for all three subjects before and after the study, and with SCS open and closed. As shown in the table, no participant showed improvement exceeding 20% ​​when comparing SCS open and closed. However, when comparing pre- and post-study results, SMA02 and SMA03 showed improvement of more than 50% over time. The improvement in SMA01 was relatively low, but this was because SMA01 had the least disease progression among all subjects and its ROM during exercise was within normal biomechanical limits.

[0239] The improvements in the hip were more pronounced in SMA02 and SMA03. Specifically, the knee ROM in SMA02 also showed significant improvement. This is likely due to the severe disease progression and limited ROM in SMA02, which allowed for maximum improvement. Overall, for all subjects and all joints, ROM significantly improved post-study compared to pre-study levels.

[0240] Ground walking gait: Gait pattern changes in SMA01 and SMA02 during a 6-minute walk test (in which subjects walk as fast as possible within 6 minutes) were analyzed over a four-week period. Using the same method as the PCA experiment described in the “Observed Immediate Effects” section above, data from week 2 and post-removal of SMA01 were compared, as were data from pre-implantation and post-removal of SMA02. Figures 21A through 21D show the effects of the 6-minute walk test gait patterns of SMA01 and SMA02 over several weeks at the end of the study. Figures 21A and 21C show the 3D spaces defined by principal components (PCs) of SMA01 and SMA02, respectively. Figures 21B and 21D show histograms of the means of the variables that reported the largest contributions to the PCs of SMA01 and SMA02, respectively. As shown in Figures 21A and 21C, for both subjects, the gait patterns of different weeks were clearly separable along the direction of highest variability (PC1), indicating that the stimulus produced changes in gait patterns. As shown in Figures 21B and 21D, for both subjects, the characteristics of the explained variance were primarily related to joint velocity. Therefore, temporal and spatial gait variables that could indicate faster, more efficient gait were analyzed. Figures 22A through 22D show the improvement of several gait quality variables for SMA01 at the end of the study. These figures show that for both the right and left sides of SMA01, stride length increased (Figure 22A), stride height increased (Figure 22B), and stride duration decreased (Figure 22C) during the study. Figure 22D shows that stride duration for SMA01 improved, i.e., decreased, during the study. Figures 22E through 22H show the improvement of several gait quality variables for SMA02, which is similar to SMA01, at the end of the study. As shown in Figures 22A to 22H, the results for both subjects consistently indicated that, as an effect of the stimulus at the end of the study, stride length, stride height, and gait speed increased, while stride duration decreased. In summary, these results demonstrate that the stimulus intervention described in this paper can alleviate gait deficits in patients with SMA over a period of only 4 weeks.

[0241] Functional magnetic resonance imaging (fMRI) of the spinal cord: fMRI of the spinal cord was performed to assess whether functional remodeling of lumbar spine activity would occur at the end of the study with the use of SCS. Without being bound by any particular theory, improvements in SCS at the end of the study could reverse maladaptive changes in MN ion channels, improve MN dysfunction, and thus be reflected in hemodynamic signals measured during fMRI. The lumbar spine of SMA01 was scanned twice pre-implantation and once post-implantation, centered on the conus medullaris. Similarly, the lumbar spine of SMA02 was scanned twice pre-implantation and once post-implantation. The acquisition of spinal cord fMRI focused on evoking MN activation and recruiting proprioceptive afferents from specific leg muscles. This was achieved by performing task-based functional scans to measure responses to active or passive tasks. Neural activation across the entire spinal cord segment was then compared to identify active voxels and quantify the number of voxels exceeding what was considered a statistically significant threshold for activity. Responses to both active and passive tasks showed an increase in the number of active voxels and z-score voxel values ​​at the anatomically relevant spinal cord level, indicating stronger neural activation signals in the spinal cord at the end of the study compared to pre-study levels. The active task in the task-based functional scan involved subjects extending their right leg at a fixed rate in response to on-screen cues. This directly activated the MN in response to eliciting controlled movement. As shown in Figures 23 and 24, three runs were acquired during each treatment session. Figures 23A and 23B show the neural activation results of SMA01 during the active task. Figure 23A shows a bar chart representing the mean z-score of the fixed-effect mean run for each treatment session during the active task. Black error bars represent SEM, and asterisks indicate significance (p < 0.001). Figure 23B shows a histogram representing the number of active voxels at different z-score values ​​for each treatment session. The threshold for the z-score was Z > 2. As shown in Figure 23B, the number and / or activation rate of MNs increased after implantation, as indicated by the increase in the number of active voxels and their z-scores. Figures 24A and 24B show the neural activation results of SMA02 during active tasks. The results shown in Figure 24A are comparable to those in Figure 23A. Figure 24B shows a histogram representing the number of active voxels at different z-score values ​​for each treatment session. The threshold for the z-score was Z > 2.5. Although the data in Figure 24B are not statistically significant, they follow the same trend as the results for SMA01 shown in Figure 23A. Notably, the tail of the z-score distribution after removal is consistently larger than that before implantation.

[0242] Figure 39 shows the spinal cord fMRI results for SMA01, SMA02, and SMA03 during an active task (i.e., voluntary leg movement). The z-score is a statistical value used to determine whether voxels have been activated. Activation of the L1 to S1 spinal cord segments targeted by SCS therapy was calculated based on the z-score. An increase in the number of activated voxels was observed in all subjects, indicating that the spinal cord circuits in the subjects were more neurally active than pre-study levels four weeks after SCS treatment. Detailed methodologies for the fMRI are provided in the Supplementary Data section.

[0243] The passive task in the task-based functional scan involved a physical therapist performing limb movements. When the limb (e.g., the right leg) was moved, muscle spindles were recruited by extending the muscles into which they were embedded. The physical therapist extended the right knee at a fixed rate in response to an audio cue. Three runs were acquired during each session, as shown in Figure 25. Figures 25A and 25B show the neural activation results of SMA01 during the passive task. Figure 25A shows a bar chart representing the mean z-score of the fixed-effect mean run for each session during the passive task. Figure 25B shows a histogram representing the number of active voxels at different z-score values ​​for each session. The threshold for the z-score was Z > 2.5. As shown in Figure 25B, the number of MNs and / or the activation rate of MNs increased after implantation, as indicated by the increase in the number of active voxels and their z-scores. This is likely due to increased recruitment of proprioceptive afferent nerves after implantation. In addition to the functional series, T2 anatomical images and physiological (heart rate, respiration) signals were acquired during each run. Data were analyzed using a general linear model.

[0244] Observed long-term effects

[0245] In this example, the long-term effects of SCS were measured based on MN resistance / recruitment, MN activation rate, maximal voluntary contraction, and ground walking gait. These measurements were performed several weeks after the patient's electrodes were removed (e.g., more than 50 days later) and illustrate changes in the patient's motor function several weeks after SCS was not applied. Each measurement is discussed below. It should be understood that different metrics may be used depending on the patient's target muscles or conditions.

[0246] Four weeks of SCS treatment combined with walking and strength training significantly and powerfully improved strength, fatigue, and motor performance in all subjects. The long-term effects of SCS treatment surpassed those of all other known SMA treatments. These changes correlated with the electrophysiological and imaging characteristics of changes occurring in the spinal cord (specifically the spinal MN), indicating that the spinal MN exhibited reduced hyperexcitability and higher activating rates after SCS treatment. This suggests that SCS treatment is a disease-modifying intervention that alters the neural properties of motor neurons affected by SMA, thereby improving motor performance. Generally, all functional and electrophysiological changes were inversely proportional to disease progression (i.e., a greater effect on SMA01 with milder disease progression and a smaller effect on SMA02 with more severe disease progression). These findings suggest that SCS treatment should be offered to SMA patients as soon as possible to maximize its efficacy.

[0247] Although patients receiving SMA therapy (SMA02 and SMA03, both treated with nusinersen) did not show significantly better outcomes than patients not receiving SMA therapy (SMA01) throughout the four-week trial, the effectiveness of SMA therapy became apparent during long-term follow-up of the trial. Patients not receiving SMA therapy tended to show a long-term decline in the beneficial effects of SCS. Conversely, the two patients who received SMA therapy during SCS surprisingly showed long-term stability of the beneficial effects of SCS. These findings suggest that SCS treated with SMA therapy has better long-term efficacy compared to SCS that does not receive SMA therapy concurrently.

[0248] MN Resistance / Recruitment: Compared to healthy MNs, MNs affected by SMA have abnormally high input resistance, thus exhibiting overexcitation. This overexcitation makes SMA-affected MNs abnormally easy to recruit. By treating SMA-affected MNs with SCS, the input resistance of MNs can be reduced, making their function more similar to that of healthy MNs.

[0249] Transcranial magnetic stimulation (TMS) is a method that generates action potentials (and thus motor evoked potentials (MEPs) in the MN by stimulating the corticospinal tract (i.e., the brain structure connecting the human motor cortex to the human spinal cord MN). This pathway is independent of the spinal cord structure stimulated by SCS, thus providing a method to independently assess spinal cord MN excitability by examining the intensity of MEP evoked by TMS pulses. Figure 40 uses a network diagram to show the percentage change in MEP interpeak amplitude for SMA01, SMA02, and SMA03. Bold heptagonal lines represent lines with no change. Compared to pre-study values, all participants showed a significant decrease in MEP interpeak values. The change was inversely proportional to disease progression, with the largest change observed in SMA01. The data indicate that the spinal cord MN in all subjects showed reduced excitability in response to SCS treatment. This confirms the hypothesis that the changes observed in clinical scores, motor performance, and / or strength are caused by the effects of SCS at the MN level. (Figures 41 and 42 show how the interpeak MEP changes with pulse intensity for different subjects.)

[0250] As shown in Figures 29A to 29C (which illustrate data from SMA02), for pulses of the same intensity, MN was more difficult to recruit after the study than before. Therefore, the input resistance of MN was greater after the study, implying that, overall, MN functioned more similarly to healthy MN after SCS treatment combined with SMA therapy. As shown in Figure 29A, there were differences between pre- and post-study measurements of TMS-induced motor evoked potentials (MEPs) of the rectus femoris (represented by inter-peak amplitude readings at various TMS pulse intensities). Post-study amplitude readings were significantly lower than pre-study amplitude readings, particularly at stronger TMS pulse intensities (85%+). As shown in Figures 29B and 29C (which illustrate the response amplitude of TMS pulses over time at 90% and 95% intensities, respectively), post-study readings had smaller inter-peak amplitudes than pre-study readings. As shown in Figures 29A to 29C, the changes in MN input resistance before and after the study were similar to those observed for SMA01 (not shown).

[0251] MN Activation Count / Rate: Figures 43A through 43C illustrate single MN firings from surface EMG signals of SMA01, SMA02, and SMA03 during isometric maximal voluntary contraction of the knee extensors and flexors, respectively. Based on high-density EMG data, the number of observed MN units, their peak activation rate, and their “nervous area” (i.e., how much muscle a single MN activated) were calculated. No significant trend in the number of MN units was detected during the study period in all three subjects. This is likely at least in part because surface EMG is not a reliable measure of the actual number of motor neurons, as the number of detected units depends on electrode placement and other trophic factors. Regarding the peak activation rate, higher peak activation was observed in all three subjects at the end of the four-week study. A higher activation rate indicates the ability of MN units to increase force when needed, which correlates with changes in torque and demonstrates changes in MN levels. The nervous area was calculated by observing the magnitude of the electrical signal per unit on the high-density electrode patch. Using this measurement method, an overall average increase in the size of detected MNs was observed during the four-week study period. This correlated with the observed increase in muscle strength in the subjects. In short, at the end of the SCS treatment study, MN showed a faster activation rate and a larger area of ​​nerve innervation on the muscle.

[0252] Figures 26A and 26B illustrate the MN activation rate of SMA01 at different points during and after the study, according to some embodiments, during and after the study. Figure 26A plots the activation rates of the two MNs (Unit 1 and Unit 2) and the change in maximum knee extension torque over time, illustrating how the maximum activation rate was determined. Figure 26B shows the change in MN activation rate during and after the study. Throughout the SCS treatment study, from week two to week three of the four-week experiment, the activation rate increased from below 60 peaks / second to above 64 peaks / second. Immediately following the end of the study, shortly after the SCS electrodes were removed, the activation rate remained around 64 peaks / second, indicating that the benefits of SCS treatment (i.e., the increase in MN activation rate) persisted within this timeframe. However, in long-term follow-up, several weeks after removal, the activation rate dropped to approximately 60 peaks / second, suggesting that the benefits of SCS treatment diminish over time once the stimulation is removed. Therefore, as shown in Figure 26B, the improvement in activation rate associated with SCS treatment in SMA01, both immediately and at the end of the study, experienced a long-term regression. This long-term regression is thought to be because SMA01 was not concurrently treated with SMA during SCS.

[0253] Maximum Spontaneous Contraction: Figures 30A to 30C show the long-term variation of torque measurements for SMA01 and SMA02. Points correspond to the maximum torque generated during a single test, and square markers represent the average value for the same day of testing. Figure 30A shows the measurements of maximum left hip flexion torque of SMA01 at different points before (-9 days), during (5 and 18 days), and after (+3 and +52 days) the four-week test period. As shown, the MVC of SMA01 increased significantly during the test (from -9 days to 18 days) but decreased over the long term (from +3 days to +52 days after removal). Similarly, the increase in torque associated with SCS treatment in SMA01 at the immediate and end-of-study stages (as shown in Figures 7A to 7E, 12A to 12C, 13A to 13C, 14A to 14C, and 15A to 15C) experienced a long-term regression, which is believed to be because SMA01 was not receiving SMA therapy concurrently with SCS treatment.

[0254] Compared to SMA01, SMA02 showed improved muscle strength even after SCS treatment ended. Figure 30B shows the measurements of maximum left hip flexion torque in SMA02 at different points before (-6 days) and after (+5 and +55 days). As shown, the left hip MVC in SMA02 did not increase significantly during the experiment (from -6 days to +5 days), but unexpectedly, it increased significantly in the long term (from +5 days after removal to +55 days). Even after SCS treatment ended, the patient's muscle strength improved. However, this differs from Figure 30C, which shows the measurements of maximum right hip flexion torque in SMA02 at different points throughout the experiment. As shown, the right hip MVC in SMA02 decreased in the long term, although its left hip MVC increased within the same timeframe. In conclusion, these figures suggest that the beneficial effects of SCS, when combined with SMA therapy, may be preserved in certain muscles in the long term.

[0255] Figure 44 shows the long-term variation of isometric maximum torque measurements generated by left and right hip flexion in SMA01 and SMA03. Points correspond to the maximum torque generated during a single trial, and square markers represent the average values ​​from trials on the same day. As shown, when SCS is applied early in the study, in some cases, SCS appears to have a significant immediate effect relative to no SCS (e.g., for SMA01, on day 5, with SCS, the right hip increased by +18% compared to no SCS; for SMA03, on day 10, with SCS, the left hip increased by >+20% compared to no SCS), but in other cases, there is little immediate effect (e.g., for SMA01, the left hip on day 19; for SMA01, the right hip on day 19; for SMA02, the left hip on days 16 and 26; for SMA02, the right hip on days 10 and 25). Therefore, the immediate effect of SCS is only observed early in the study and is not bilateral. Even without SCS, both subjects retained the improvement in torque generation after the study ended.

[0256] Ground walking gait: Figures 31A through 31H illustrate the long-term changes in several gait quality variables for SMA01 and SMA02. Figures 31A through 31D show that for SMA01, stride length (Figure 31A) and gait duration (Figure 31C) remained largely constant over the long term, but stride height (Figure 31B) and gait speed (Figure 31D) decreased significantly between measurements at the end of the study (within 1 week after removal) and long-term measurements (more than 50 days after removal). These results suggest that the long-term effects of SCS alone (without concurrent SMA therapy) may decrease over time, potentially impacting gait quality in patients. Conversely, Figures 31E through 31H show that for SMA02, stride length (Figure 31E), stride height (Figure 31F), gait duration (Figure 31G), and gait speed (Figure 31H) did not decrease significantly between measurements at the end of the study and long-term measurements. These results suggest that when SCS is combined with SMA therapy, the long-term effects of SCS may be preserved over time, and patients' gait quality may remain at the level at the end of the study even weeks after the SCS electrodes have been removed.

[0257] Fatigue: Fatigue was quantified using a 6-meter walk test. For SMA02 and SMA03, fatigue was quantified using the ratio of gait speed in the last lap to gait speed in the first lap. For SMA01, which can complete a large number of laps, this ratio was calculated using the average of the first three laps and the last three laps.

[0258] Figure 45 shows a table of fatigue values ​​for SMA01, SMA02, and SMA03 before, during, and after the study. The calculated fatigue values ​​represent the performance decline due to fatigue. For example, a value of 0.46 (as shown for SMA02 at the start of the study) means that the speed on the last lap was only 46% of the speed at the start of the test, indicating considerable fatigue. Overall, fatigue in SMA01 did not change significantly throughout the study. The fatigue value was close to 100%, indicating that SMA01 did not experience particular fatigue during the 6MWT. In contrast, both SMA02 and SMA03 experienced considerable fatigue (approximately 40-50) at the start of the study (enrollment). During the study, the fatigue value of SMA02 increased significantly and remained at a high level several weeks after follow-up. For SMA03, fatigue increased significantly during the study but decreased back to the pre-study value. However, fatigue calculations are only estimates used to quantify fatigue and do not represent the full picture of the benefits of SCS treatment. For example, Figure 46 shows the lap speed at 6MWT and demonstrates a significant improvement in lap speed for all subjects.

[0259] Clinical outcome testing

[0260] Clinical outcome tests were conducted, including manual muscle testing, a 6-minute walk test, and a leg circumference test. Immediate, end-of-study, and long-term effects were observed in the clinical outcome tests, as discussed below.

[0261] Manual Muscle Testing (MMT): The manual muscle testing (MMT) is a widely accepted method for assessing muscle strength. It measures the strength of each muscle separately and then sums the individual strength measurements to report a total score. MMT was performed on SMA01 before implantation and on days 14 and 28 post-implantation. MMT showed a consistent immediate effect of stimulation. Specifically, scores for both knee extensor / flexor and hip extensor / flexor muscles improved after stimulation, as shown in the spreadsheet in Figure 16, which contains manual muscle test scores for SMA patients with and without stimulation, broken down by muscle and treatment duration.

[0262] Six-minute walk test: Six-minute walk tests (6MWT) were performed on SMA01, SMA02, and SMA03 before implantation, on day 14 (with and without stimulation), after electrode removal, and more than 50 days after removal. No significant immediate effects from the stimulation were observed, but a significant improvement in total walking distance was observed at the end of the four-week study for all subjects, as shown in the tables shown in Figures 17A to 17C and Figure 47. Therefore, the effect of the stimulation at the end of the study included an increase in total walking distance for all subjects. However, the long-term effects of SCS differed among SMA01, SMA02, and SMA03. In long-term measurements (more than 50 days after removal), the total walking distance of SMA01 decreased relative to its end-of-study result, as shown in Figure 17B. Conversely, the total walking distance of SMA02 during long-term measurements increased slightly relative to its end-of-study result, as shown in Figure 17C. The total distance walked by SMA03 during the long-term measurement period was lower than the measurement at the end of the study, but still higher than the initial measurement, as shown in Figure 47. In summary, this may indicate that when SCS is combined with SMA therapy (as in SMA02 and SMA03), the long-term effects of SCS may be preserved to some extent over time, and the increase in walking distance may be maintained to some extent even several weeks after the SCS electrodes have been removed, rather than degenerating over time as in patients whose SCS was not combined with SMA therapy (such as SMA01).

[0263] Figure 17A shows the distance traveled by SMA01 during 6MWT cycles at different treatment sessions, comparing stimulation off and stimulation on during the study period (day 14). Figure 17B expands this dataset, showing the distance traveled by SMA01 during 6MWT cycles at different treatment sessions, specifically comparing distances before implantation, at the end of the study, and at follow-up. Similarly, Figure 17C shows the distance traveled by SMA02 during 6MWT cycles at different treatment sessions. Figure 47 shows the same distances as Figures 17A to 17C, with additional distance information for SMA03.

[0264] In the existing literature, one clinical study investigated the effects of physical exercise on the 6MWT in adults with dynamic SMA. (Montes, J. et al., A randomized, controlled clinical trial of exercise inpatients with spinal muscular atrophy: methods and baseline characteristics. J. Neuromuscul. Dis. 1, 151–161 (2014); Bartels, B., Montes, J., van der Pol, WL & de Groot, JF Physical exercise training for type 3 spinal muscular atrophy. Cochrane Database Syst. Rev. (2019).) That study found that after 6 months of physical exercise, participants showed an average improvement of only 9 minutes in the 6MWT. In this experiment, by incorporating SCS in addition to physical exercise, each participant achieved at least a twofold improvement over a shorter time span (four weeks), regardless of the severity of their SMA. The improvement in 6MWT was proportional to the HFMSE at enrollment for each subject, but all were greater than 20m, as shown in Figure 48. Coincidentally, SMA02, who participated in both the pure exercise clinical study and the four-week trial including SCS, showed a 0m increase in 6MWT after 6 months in the pure exercise clinical study, but a 20m increase in the four-week trial including SCS.

[0265] Clinical scales, the Hammersmith Functional Motor Scale Extension (HFMSE), and the Revised Hammersmith Scale (RHS): The HFMSE and RHS tests are validated tools for assessing motor function in children and adults with type 2 and type 3 SMA. Results of the HFMSE and RHS tests were measured before implantation, on the day of removal (at the end of the study), and during long-term follow-up after removal. The HFMSE test for SMA01 (without SMA therapy) showed a small but relevant long-term effect, with an increase in the total score and a final HFMSE score of 61. Improvements in the HFMSE are often difficult to achieve for patients. Therefore, even small changes (1 to 2 points in this case) indicate improvement, as shown in the tables in Figures 18A and 18B, which contain the HFMSE scores for SMA01. Similarly, as shown in the table in Figure 18B, the RHS test for SMA01 showed a pre-implantation RHS score of 64 and a post-removal RHS score of 65 (an increase of 1 point). The increase in HFMSE and RHS scores remained consistent at 52 days post-removal, indicating a small but relevant long-term effect associated with the four-week trial.

[0266] Figure 18C shows the HFMSE and RHS test scores for SMA02 (receiving SMA therapy), exhibiting similar long-term trends. The score at the end of the study increased by several points relative to the pre-implantation score of SMA02, and this increase persisted for 55 days post-removal, indicating a long-term effect associated with the four-week trial. Although the score increase for SMA02 was greater than that for SMA01, the baseline motor impairment for SMA02 was more severe than that for SMA01. In conclusion, these figures suggest that in both cases, patients may experience small but lasting improvements in motor function that are not necessarily lost over the long term.

[0267] Thigh circumference: On day 18 post-implantation, the left and right thigh circumferences of SMA01 were measured at a distance of 15.24 cm above the left and right patella, respectively. The measured left and right thigh circumferences were 43.5 cm and 46 cm, respectively. On day 5 after the four-week trial and removal, the patient's left and right thigh circumferences at the end of the study were measured at 44 cm and 45 cm, respectively. These small differences may be considered insignificant.

[0268] Supplementary data

[0269] Figures 49A through 49C provide an overview of gait changes in SMA01, SMA02, and SMA02 during the four-week experimental period. Subject performance is shown between trials with and without SCS throughout the different weeks of the experiment. Performance was measured against gait quality variables, specifically stride height, stride length, and gait speed, all calculated using full three-dimensional limb kinematics. Significant increases in all gait quality variables were observed in all subjects between the initial and final measurements. These increases in gait quality variables indicate a significant improvement in gait quality and demonstrate that every patient experienced gait improvement after SCS treatment, regardless of SMA severity. For each assessment, the immediate effects of SCS on and off slightly altered subject performance; conversely, the largest changes were observed between the initial and final measurements, suggesting that SCS can induce long-term improvements in gait quality.

[0270] Figure 35 illustrates the torque generated by SMA01 during maximal isometric contractions in various movements. Each point represents a single instance of maximal spontaneous contraction tested daily. These points are vertically grouped based on the time of the test (e.g., pre-implantation / week 1, post-study / week 4, and / or 6 weeks after the end of the study).

[0271] Figure 36 illustrates the torque generated by SMA03 during maximal isometric contractions in various movements. Each point represents a single instance of maximal spontaneous contraction tested daily. These points are vertically grouped based on the time of the test (e.g., pre-implantation / week 1, post-study / week 4, and / or 6 weeks after the end of the study).

[0272] Figure 50 shows the TMS recruitment curves of SMA01 before implantation and at the end of the study (week 4). Each data point represents the interpeak MEP value for different stimulation intensities, plotted along the x-axis.

[0273] Figure 41 shows the TMS recruitment curves of SMA02 before implantation, during week 3 of the study, and after removal. Each data point represents the MEP peak value at different stimulation intensities, plotted along the x-axis.

[0274] Figure 42 shows the TMS recruitment curves of SMA03 before implantation, during week 3 of the study, and after removal. Each data point represents the MEP peak value at different stimulation intensities, plotted along the x-axis.

[0275] fMRI Data Acquisition: Participants lay comfortably in a supine position within the scanner (Siemens Prisma 3Tesla). A spinal coil was used. Participants were instructed to relax, remain still, and breathe normally. All three participants underwent at least three days of independent experimental recording involving active limb movements to stretch specific muscle groups. Functional acquisition was performed using gradient echo planar sequences and ZOOMit field imaging, with a repetition time (TR) of 2.5 s, echo time (TE) of 34 ms, field of view (FOV) of 48 x 144 mm, flip angle of 80°, in-plane resolution of 1.0 mm x 1.0 mm, and slice thickness of 3 mm. Thirty-two axial slices were acquired per volume. The basal slice was placed at the distal end of the conus medullaris, around the T12 / L1 vertebra. Manual shimming of the spinal cord was performed to adjust field homogeneity. Physiological data (respiratory and cardiac signals) were directly acquired using MRI-compatible optical volumetric plethysmography and respiratory bands (for SMA02 and SMA03). T2-weighted high-resolution anatomical images (sequence SPACE, resolution 0.4 mm x 0.4 mm x 0.8 mm, TR = 1.5 s, TE = 135 ms) were acquired for registration and normalization purposes.

[0276] Spinal cord fMRI and preprocessing: Lumbar and sacral spinal cord fMRI was performed to visualize the activation of neuronal projection groups innervating specific muscles. The fMRI preprocessing, processing, and analysis workflow is based on recent cervical and lumbar spinal cord fMRI studies. (Rowald, A., Komi, S., Demesmaeker, R. et al., Activity-dependent spinal cord neuromodulation rapidly restores trunk and leg motor functions after complete paralysis. Nat Med 28, 260–271 (2022); Kinany N, et al., Dynamic functional connectivity of resting-state spinal cord fMRI reveals fine-grained intrinsic architecture. Neuron 2020;108(3):424–435 e4; Kinany, N., Pirondini, E., Martuzzi, R., Mattera, L., Micera, S., Van de Ville, D., 2019. Functional imaging of rostrocaudal spinal activity during upper limb motor tasks. Neuroimage 200, 590–600.) This protocol was tailored to image the lumbar spinal cord. The protocol involved three runs of active leg movement. Each run consists of a 16-second activity block in which participants extend their knees at a rate of 0.5 Hz. One run comprises 9 activity blocks and lasts for a total of 6 minutes.

[0277] fMRI preprocessing was performed using the FMRIB Software Library (FSL) v5.0.15 and the Spinal Cord Toolbox (SCT) v5.0. Motion correction was performed using the SCT Toolbox. Mean functional images were used to automatically detect the spinal cord centerline. A cylindrical mask (30 mm in diameter) was generated along the centerline to prevent the inclusion of regions independent of spinal cord movement, and slice realignment was performed with the mean functional images as a reference. Three-dimensional rigid body realignment (spline interpolation and least-squares cost function) was used to align all runs corresponding to the same scan session with the first run of that session. All images were examined to ensure any artifacts of insufficient signal were removed. Motion scrubbing was also performed using the FSL tool to identify aberrant volumes, where the DVARS (root mean square of intensity differences between 26 consecutive volumes) index was used in the spinal cord, with a box plot cutoff value (75th percentile + 1.5 x interquartile range). Cerebrospinal fluid and spinal cord were automatically segmented from the mean functional images using SCT (with manual corrections as needed). Using a RETROICOR-based approach, interference regressions were constructed on acquired cardiac and respiratory signals using FSL's physiological noise modeling tool. Low-order and high-order Fourier expansions were used to model the physiological signals, resulting in 32 noise regressions, including an additional cerebrospinal fluid regression (10% of the most variable cerebrospinal fluid). These 33 physiological noise regressions (PNM and CSF) were combined with motion correction parameters (i.e., two sliced ​​regressions for motion in the x and y directions) and motion outliers, and regressions were performed from the fMRI time series using FSL's fMRI Expert Analysis Tool (FEAT). The full width at half maximum (FWHM) was then used at 2 × 2 × 6 mm. 3 The residuals were spatially smoothed using a 3D Gaussian kernel. Smoothing was performed along the central line of the spinal cord to maintain anatomical consistency. Finally, the acquisition times corresponding to the task design were submitted to a specific first-level generalized linear model. A second-level fixed-effects analysis (subject level) was performed by combining these three runs. Where possible, multiple comparison corrections were performed (Z > 1.5, p < 0.05); otherwise, the possible atlases were uncorrected (Z > 1.5, p < 0.05). The atlases before or after implantation were then averaged.

[0278] High-resolution structural MRI was used to identify spinal cord segments L1 through S2. Identification of the L1 dorsal root extends from its entry point into the vertebral canal (just below the L1 vertebra) to the area it innervates, defining the L1 spinal cord segment. Further caudal segments (L2–S2) were identified by tracing the dorsal root along the cephalotochirhinal axis. The analysis window focused between the level of a single vertebra and the level of the nerve roots involved in leg extension movements.

[0279] Additional discussion of subjects SMA01, SMA02, and SMA03

[0280] After several weeks of testing on subjects, a significant abrupt increase in maximum force was observed from week one to week two, even without stimulation. Torque changes over time were investigated, revealing a surprisingly large increase in almost all leg muscles, particularly the hip flexors and extensors, and knee extensors and flexors, in all participants. These changes began to appear in week 2 and accelerated significantly from week 3. When assessing all joint movements, the changes appeared to be concentrated in the hip muscles, which are the direct targets of the stimulation program, most susceptible to SMA, and less trained in knee-focused exercises. Notably, these improvements extended far beyond the scope of the assistive effects and resulted in significant motor benefits over time. For example, as the assistive effects accumulated on top of the newly acquired strength, SMA03 was able to stand up from a desk-leaning position by week 4, a task the participant could not accomplish before the study began without SCS. In summary, measurable assistive effects on strength were found when SCS was activated, and these effects paralleled the dramatic changes in strength observed abruptly within four weeks without stimulation.

[0281] Improvements were also observed in fatigue and gait. Despite significant differences in initial deficits among participants, gait variables (step height, step length, and gait speed) improved significantly in all three participants within 4 weeks. Importantly, further improvements in step height, step length, and gait speed were observed when SCS was activated, with noticeable changes in gait patterns identified even within the same treatment course. In particular, SMA02 showed significant improvement in gait quality—they had severe muscle degeneration and were unable to bend their knees at all before the trial, but their gait completely changed after treatment, allowing them to fully bend their knees. When SCS was activated, the kinematic changes paralleled the immediate increase in EMG power, with modulation of EMG activity increasing over time, indicating that kinematic movement was driven by changes in muscle activation. Using the standardized 6MWT to assess improvements in fatigue, it was surprising to find improvements exceeding 20m in all three participants within just 4 weeks (compared to a minimum clinically significant difference of 14m). Furthermore, both 6MWT and fatigue were improved, whereas previous reports indicated no association between these two factors. This suggests that the participants' motor syndrome in this study was intrinsically altered due to SCS.

[0282] The degree and speed of the observed improvements in strength and motor control suggest that they may be caused by neural drive rather than changes in muscle mass. To assess this, high-density electromyography (HDEMG) was used during maximal voluntary contraction, and single motor unit firing was extracted. It was found that the total firing rate of motor units increased when SCS was activated. When comparing the firing rates of motor neurons before and after the study, the unit firing dynamics among the pre-study units were very consistent at the generation of isometric force. However, the new units that emerged after the study appeared to have significantly different behavior. These units exhibited significantly higher firing rate bursts at the onset of force, which correlated with the higher peak values ​​obtained experimentally (Fig. 51A). The firing rate distribution of this peak was significantly different from any other units recorded before the study, and these units were labeled “rescued units” because they exhibited significantly higher acquired firing capacity. These rescued units with very similar behavior were found in all three participants. Figs. 51A and 51B provide the trajectories of single-unit motor neuron firing rates during maximal voluntary contraction under isometric conditions. Salvaged motor neurons were defined as those that, during repetitions (n ​​= 6), had a mean peak firing rate higher than the 99.7th percentile of the mean peak firing rate during the pre-study treatment period. Raster plots show the peak times of two example motor neurons. Figure 51A shows examples before and after the study, while Figure 51B shows a comparison with and without stimulation. Figures 52A and 52B quantify the mean peak firing rate for each of the three patients under all isochronous conditions before and after the study (Figure 52A) and with and without stimulation (Figure 52B).

[0283] More detailed information about the clinical trial can be found at Clinicaltrials.gov, identifier NCT05430113, “Spinal Cord Stimulation in Spinal Muscular Atrophy (SCSinSMA)”, at [website address missing]. https: / / clinicaltrials.gov / ct2 / show / NCT05430113 .

[0284] Example 3

[0285] Spinal cord stimulation therapy for upper limb muscle defects in SMA subjects

[0286] In this study, SMA patients will be recruited and their cervical spinal cord will be stimulated using SCS.

[0287] Prior to electrode implantation, each subject will undergo a detailed medical history and physical examination, as well as a thorough musculoskeletal and neurological examination. The Physical Activity Disability Survey (PADS) and the revised Hammersmith Functional Scale (RHS) will be administered, assessing the subject's ability to stand independently for at least 3 seconds. Preoperative high-resolution MRI will be performed, obtaining images including high-resolution T1-weighted images, high-resolution T2-weighted images, and diffusion tensor imaging (DTI). The same brain images will also be obtained at the end of the study to document potential structural changes in fiber tracts that may be associated with brain plasticity and motor recovery. Functional magnetic resonance imaging of the spinal cord will also be obtained in the resting state and during muscle contraction, with the same images obtained at the end of the study to document potential changes in brain and spinal cord functional connectivity that may be associated with plasticity and motor recovery.

[0288] For SCS testing, two to four eight-pole Medtronic leads are temporarily implanted in the epidural space of each patient's C4 to T1 vertebrae. This portion of the vertebrae contains nerve roots that innervate the muscles of the trunk, back, and upper limbs. The device is percutaneously passed through the skin and secured in place with tape, remaining external for up to 29 days. During the SCS testing period, the leads are connected to an external stimulator. Examples of external stimulators that can be used are the Natus MedicalProtektor32, the Digitimer DS8, or Medtronic's Intellis system external wireless stimulator.

[0289] Following implantation, each subject will participate in a series of electrophysiological stimulation tests. Stimulation parameters will vary but will remain within the following ranges: pulse amplitude between 0.2 and 10 mA; pulse frequency between 0.1 and 500 Hz; and pulse width between 100 and 400 µs. EMG responses and joint kinematics to the series of stimuli will be recorded, and subjects will be asked to answer a set of standard psychophysical questions to assess possible levels of discomfort and provide any additional comments. Patients will also participate in various motor task assessments to measure the effects of the SCS on upper limb function, including the deltoid, biceps, triceps, and wrist extensor flexors.

[0290] KINARM System: Because the SCS recruits proprioceptive afferents in the dorsal root, it is crucial to assess each subject's ability to consciously and unconsciously process proprioceptive feedback. Each subject's active proprioceptive ability will be assessed by arm movement assessments performed on the KINARM system (Kinarm, Kingston, ON, Canada) at baseline, day 29, and follow-up. KINARM is a system used in human studies to assess motor performance in stroke subjects. Participants will sit in a chair with their arms supported against gravity. Participants will be asked to actively perform isotonic elbow extension and flexion movements, for example, against constant opposing forces of 0%, 10%, 20%, and 30% of maximal voluntary surface electromyography (EMG). Surface EMG of major arm muscles will be recorded. Throughout the experiment, the participant's line of sight to their arms and hands will be obscured by a protective screen built into the KINARM system. Each patient's ability to assess limb position and joint movement will be assessed.

[0291] CSMi's HUMAC NORM: To quantify the range of motion of the arm joint and the joint torque with and without SCS, each patient will be assessed using the clinical isokinetic testing system: CSMi's HUMAC NORM. These data can be captured at baseline, within 29 days of implantation, and at follow-up.

[0292] Hand-cranked bicycle: The effects of the SCS will also be assessed using a hand-cranked bicycle. Patients will be asked to use the hand-cranked bicycle for as long as possible on a regular basis. The SCS will be provided during these trials to validate its effect on motor task performance. Subjects will use the hand-cranked bicycle at their preferred speed and resistance, either in the SCS or in a no-stimulation controlled trial. Parameters assessed will include torque asymmetry between the arms, time, distance, and speed. This assessment can be performed pre-implantation (baseline), during implantation, and at follow-up after implant removal to evaluate the effects of the SCS on upper limb function.

[0293] Three-Dimensional Reaching / Simulated Activities of Daily Living (ADL) Task: Upper limb function will also be assessed through a three-dimensional reaching / simulated activities of daily living (ADL) task. Patients will be asked to reach for and grasp custom-built objects. Each object will promote a specific type of grasp. For example, a large sphere will promote a strong full-hand grasp, a cylinder will promote a cylindrical grasp, and a flat-shaped object will promote a precise index-thumb pinch. The objects can be placed in space using a tactile robot capable of measuring grasping forces and interaction forces.

[0294] Primary outcomes related to muscle strength will be assessed before the study, at week 2, week 4, and at follow-up at the end of the study (at least 4 weeks after completion). The SCS lead will be removed within 29 days of device placement.

[0295] Enumerated Examples

[0296] This disclosure will now be further described by way of the following numbered embodiments, which will be read in conjunction with the preceding paragraphs and do not limit the scope of this disclosure. The features, options, and preferences described above also apply to the following embodiments.

[0297] Example 1. A method for treating spinal muscular atrophy (SMA) in a subject, the method comprising: applying a therapeutically effective amount of electrical stimulation to sensory neurons innervating a body region of the subject that has motor impairment due to SMA, wherein the electrical stimulation is applied via one or more electrodes controlled by a neurostimulator, and wherein the application of the electrical stimulation treats the motor impairment caused by SMA in the subject.

[0298] Example 2. The method according to Example 1, wherein applying electrical stimulation increases the probability of activation of spinal motor neurons in body regions innervated by subjects with motor impairment due to SMA.

[0299] Example 3. The method according to Example 1 or Example 2, wherein stimulation is applied at or below a motion threshold such that the stimulation does not directly cause movement and / or muscle activity in the body regions of the subject with motor impairment due to SMA.

[0300] Example 4. The method according to any one of Examples 1 to 3, wherein the electrical stimulation comprises an electrical pulse having an amplitude of about 10 µA to about 100 mA, a width between about 40 µs and about 2 ms, and a frequency of about 10 Hz to about 2000 Hz.

[0301] Example 5. The method according to any one of Examples 1 to 4, wherein the electrical stimulation comprises an electrical pulse having an amplitude of about 10 µA to about 10 mA, a width between about 40 µs and about 2 ms, and a frequency of about 10 Hz to about 1000 Hz.

[0302] Example 6. The method according to any one of Examples 1 to 5, wherein the electrical stimulation comprises an electrical pulse having an amplitude of about 100 µA to about 10 mA, a width between about 40 µs and about 500 µs, and a frequency of about 10 Hz to about 1000 Hz.

[0303] Example 7. The method according to any one of the foregoing embodiments, wherein the electrical stimulation comprises a stimulation pattern of 2 to 5 pulses separated by a pulse interval of about 3 ms to about 10 ms, and wherein the series is repeated at a frequency of about 10 Hz to about 100 Hz.

[0304] Example 8. The method according to Example 7, wherein the stimulation pattern is a series of 3 pulses separated by a pulse interval of about 5 ms, wherein the series is repeated at a frequency of about 30 to about 100 Hz, and wherein the pulse width is about 200 µs.

[0305] Example 9. The method according to any one of Examples 4 to 8, wherein the pulse is a cathode-preferred biphase or single-phase charge balance pulse.

[0306] Example 10. The method according to any one of the foregoing examples, wherein electrical stimulation is applied for at least 2 hours / day during a period of at least 6 months.

[0307] Example 11. The method according to any one of Examples 1 to 9, wherein electrical stimulation is applied for at least 1 hour / day during a period of at least 1 month.

[0308] Example 12. The method according to any one of the foregoing examples, wherein one or more electrodes are contained within an array of independently controllable electrodes implanted in the subject.

[0309] Example 13. The method according to Example 12, wherein the electrode array is a multi-electrode paddle array.

[0310] Example 14. The method according to any one of the preceding examples, wherein one or more electrodes are epidurally implanted in the spinal cord of the subject.

[0311] Example 15. The method according to any one of Examples 1 to 14, wherein one or more electrodes are implanted at the dorsal root of one or more sensory neurons in a body region innervating a subject with motor impairment.

[0312] Example 16. The method according to any one of Examples 1 to 14, wherein one or more electrodes are implanted in the dorsolateral position of the spinal cord adjacent to the dorsal root of one or more sensory neurons in a body region innervating the subject with motor injury.

[0313] Example 17. The method according to any one of Examples 1 to 13, wherein one or more electrodes are implanted at the dorsal root ganglion of one or more sensory neurons in a body region innervating a subject with motor impairment.

[0314] Example 18. The method according to any one of Examples 1 to 12, wherein one or more electrodes are contained in a sleeve surrounding a peripheral nerve containing sensory neurons innervating a body region of a subject with motor impairment due to SMA.

[0315] Example 19. The method according to any one of Examples 1 to 12, wherein one or more electrodes penetrate peripheral nerves or dorsal root ganglia containing sensory neurons innervating a body region of a subject with motor impairment due to SMA.

[0316] Example 20. The method according to any one of the preceding examples, wherein the subject’s body region is selected from at least one of the following: lower back, hip, leg, ankle and foot; and one or more electrodes are implanted in the dorsolateral position of the spinal cord and across one or more of the T11-S1 nerve roots.

[0317] Example 21. The method according to any one of the preceding examples, wherein the subject's body region is selected from at least one of the following: upper arm, shoulder, arm, hand, and respiratory muscles; and one or more electrodes are implanted in the dorsolateral aspect of the spinal cord and across one or more of the C3-T2 nerve roots.

[0318] Example 22. The method according to any one of the preceding examples, wherein the subject's body region is selected from at least one of the following: chest, chest wall, abdomen, upper back, and mid-back; and one or more electrodes are implanted in the dorsolateral aspect of the spinal cord and across one or more of the T3-T10 nerve roots.

[0319] Example 23. The method according to any one of the foregoing embodiments, wherein the neurostimulator is an external or implantable pulse generator.

[0320] Example 24. The method according to any one of the foregoing examples further includes implanting a neurostimulator into the subject.

[0321] Example 25. The method according to any one of the foregoing examples further includes selecting a subject suffering from SMA for treatment.

[0322] Example 26. The method according to any one of the foregoing examples, wherein the sports injury includes partial or complete paralysis, loss of dexterity, loss of muscle strength and / or uncontrollable muscle tension.

[0323] Example 27. The method according to any one of the foregoing embodiments, wherein the location of one or more electrodes is selected based on the body region of the subject who has motor injury due to SMA.

[0324] Example 28. The method according to Example 27, wherein the location of one or more electrodes is determined by: stimulating a plurality of contact points in a subject to target at least one muscle in a body region of a subject with motor impairment due to SMA; measuring electrical activity associated with the muscle in response to the stimulation; and identifying one or more of the plurality of contact points as the location of the electrodes based on the electrical activity.

[0325] Example 29. The method according to any one of the foregoing embodiments, wherein at least one of the one or more electrodes is placed percutaneously.

[0326] Example 30. The method according to any one of the foregoing embodiments, wherein at least one of one or more electrodes is implanted.

[0327] Example 31. A method of stimulating one or more motor neurons damaged by SMA, the method comprising applying electrical stimulation to at least one of the motor neurons, wherein the motor neurons innervate a body area of ​​a subject with motor impairment due to SMA.

[0328] Example 32. A method for treating a subject with spinal muscular atrophy (SMA), comprising applying a therapeutically effective amount of electrical stimulation to sensory neurons innervating a body region of the subject that has motor impairment due to SMA.

[0329] Example 33. A method for increasing the activation rate of motor neurons damaged by SMA in a subject, comprising applying a therapeutically effective amount of electrical stimulation to sensory neurons innervating a body region of the subject to increase the activation rate of the subject's motor neurons.

[0330] Example 34. The method according to Example 33, wherein the subject has a first motor neuron activation rate before the application of a therapeutically effective amount of electrical stimulation and a second motor neuron activation rate after the application.

[0331] Example 35. The method according to Example 33 or Example 34, wherein the electrical stimulation comprises an electrical pulse having an amplitude of about 10 µA to about 100 mA, a width between about 40 µs and about 2 ms, and a frequency of about 10 Hz to about 2000 Hz.

[0332] Example 36. The method according to any one of Examples 33 to 35, wherein electrical stimulation is applied for at least 1 hour / day during a period of at least 1 month.

[0333] Example 37. The method according to any one of Examples 33 to 36, wherein the motor neuron activation rate of the subject is calculated based on the electrical signals generated by the motor neurons when the electrical stimulation parameters are changed.

[0334] Example 38. The method according to any one of Examples 33 to 37, wherein increasing the activation rate of motor neurons damaged by SMA increases the subject's joint torque and muscle strength.

[0335] Example 39. A method for increasing the excitability of motor neurons damaged by SMA in a subject to sensory input, comprising applying a therapeutically effective amount of electrical stimulation to sensory neurons innervating a region of the subject's body to increase the excitability of the subject's motor neurons.

[0336] Example 40. The method according to Example 39, wherein the subject has first motor neuron excitability before the application of a therapeutically effective amount of electrical stimulation and second motor neuron excitability after the application.

[0337] Example 41. The method according to Example 39 or Example 40, wherein the electrical stimulation comprises an electrical pulse having an amplitude of about 10 µA to about 100 mA, a width between about 40 µs and about 2 ms, and a frequency of about 10 Hz to about 2000 Hz.

[0338] Example 42. The method according to any one of Examples 39 to 41, wherein electrical stimulation is applied for at least 1 hour / day during a period of at least 1 month.

[0339] Example 43. The method according to any one of Examples 39 to 42, wherein the excitability of the subject's motor neurons is calculated based on the electrical signals generated by the motor neurons when the electrical stimulation parameters are changed.

[0340] Example 44. The method according to any one of Examples 39 to 43, wherein increasing the excitability of motor neurons damaged by SMA increases the subject's joint torque and muscle strength.

[0341] Example 45. An electrical stimulation of a therapeutically effective amount for treating SMA in a subject, for innervating sensory neurons in a body region of the subject that has motor impairment due to SMA, wherein the electrical stimulation is applied via one or more electrodes controlled by a neurostimulator, and wherein the application of the electrical stimulation treats the motor impairment caused by SMA in the subject.

[0342] Example 46. The electrical stimulation used according to Example 45, wherein applying electrical stimulation increases the probability of activation rate of spinal motor neurons innervating body regions of a subject with motor impairment due to SMA.

[0343] Example 47. Electrical stimulation as described in Example 45 or Example 46, wherein stimulation is applied at or below a motor threshold such that the stimulation does not directly cause movement and / or muscle activity in the body regions of a subject with motor impairment due to SMA.

[0344] Example 48. The electrical stimulation used according to Examples 45 to 47, wherein the electrical stimulation comprises an electrical pulse having an amplitude of about 10 µA to about 100 mA, a width between about 40 µs and about 2 ms, and a frequency of about 10 Hz to about 2000 Hz.

[0345] Example 49. The electrical stimulation used according to Examples 45 to 48, wherein the electrical stimulation comprises an electrical pulse having an amplitude of about 10 µA to about 10 mA, a width between about 40 µs and about 2 ms, and a frequency of about 10 Hz to about 1000 Hz.

[0346] Example 50. The electrical stimulation used according to Examples 45 to 49, wherein the electrical stimulation comprises an electrical pulse having an amplitude of about 100 µA to about 10 mA, a width between about 40 µs and about 500 µs, and a frequency of about 10 Hz to about 1000 Hz.

[0347] Example 51. The electrical stimulation used according to any of the foregoing embodiments, wherein the electrical stimulation comprises a stimulation pattern of 2 to 5 pulses separated by a pulse interval of about 3 ms to about 10 ms, and wherein the series is repeated at a frequency of about 10 Hz to about 100 Hz.

[0348] Example 52. The electrical stimulation used according to Example 51, wherein the stimulation pattern is a series of 3 pulses separated by a pulse interval of about 5 ms, wherein the series is repeated at a frequency of about 30 to about 100 Hz, and wherein the pulse width is about 200 µs.

[0349] Example 53. The electrical stimulation used according to any one of Examples 48 to 52, wherein the pulse is a cathode-preferred biphasic or monophasic charge-balanced pulse.

[0350] Example 54. The electrical stimulation used according to any of the foregoing examples, wherein the electrical stimulation is applied for at least 2 hours / day during a period of at least 6 months.

[0351] Example 55. The electrical stimulation used according to any one of Examples 45 to 53, wherein the electrical stimulation is applied for at least 1 hour / day during a period of at least 1 month.

[0352] Example 56. Electrical stimulation used according to any of the foregoing examples, wherein one or more electrodes are contained within an array of independently controllable electrodes implanted in the subject.

[0353] Example 57. The electrical stimulation used according to Example 56, wherein the electrode array is a multi-electrode paddle array.

[0354] Example 58. Electrical stimulation used according to any of the preceding examples, wherein one or more electrodes are epidurally implanted in the subject's spinal cord.

[0355] Example 59. Electrical stimulation according to any one of Examples 45 to 58, wherein one or more electrodes are implanted at the dorsal root of one or more sensory neurons in a body region innervating a subject with motor impairment.

[0356] Example 60. Electrical stimulation according to any one of Examples 45 to 58, wherein one or more electrodes are implanted in the dorsolateral position of the spinal cord adjacent to the dorsal root of one or more sensory neurons innervating a body region of the subject with motor injury.

[0357] Example 61. Electrical stimulation according to any one of Examples 45 to 57, wherein one or more electrodes are implanted at the dorsal root ganglion of one or more sensory neurons in a body region innervating a subject with motor impairment.

[0358] Example 62. Electrical stimulation as described in any one of Examples 45 to 56, wherein one or more electrodes are contained in a sleeve surrounding a peripheral nerve containing sensory neurons innervating a body region of a subject with motor impairment due to SMA.

[0359] Example 63. Electrical stimulation as described in any one of Examples 45 to 56, wherein one or more electrodes penetrate peripheral nerves or dorsal root ganglia containing sensory neurons innervating a body region of a subject with motor impairment due to SMA.

[0360] Example 64. Electrical stimulation used according to any of the preceding examples, wherein the subject’s body region is selected from at least one of the following: lower back, hip, leg, ankle, and foot; and one or more electrodes are implanted in the dorsolateral aspect of the spinal cord and across one or more of the T11-S1 nerve roots.

[0361] Example 65. Electrical stimulation according to any of the preceding examples, wherein the subject’s body region is selected from at least one of the following: upper arm, shoulder, arm, hand, and respiratory muscles; and one or more electrodes are implanted in the dorsolateral aspect of the spinal cord and across one or more of the C3-T2 nerve roots.

[0362] Example 66. Electrical stimulation used according to any of the foregoing examples, wherein the subject’s body region is selected from at least one of the following: chest, chest wall, abdomen, upper back, and mid-back; and one or more electrodes are implanted in the dorsolateral aspect of the spinal cord and across one or more of the T3-T10 nerve roots.

[0363] Example 67. Electrical stimulation used according to any of the foregoing examples, wherein the neurostimulator is an external or implantable pulse generator.

[0364] Example 68. Electrical stimulation used according to any of the foregoing examples, wherein a neurostimulator is implanted in the subject.

[0365] Example 69. Electrical stimulation used according to any of the foregoing examples, wherein a subject with SMA is selected for treatment.

[0366] Example 70. Electrical stimulation used according to any of the foregoing examples, wherein the motor injury includes partial or complete paralysis, loss of dexterity, loss of muscle strength and / or uncontrollable muscle tension.

[0367] Example 71. Electrical stimulation used according to any of the foregoing examples, wherein the location of one or more electrodes is selected based on the body region of the subject with motor impairment due to SMA.

[0368] Example 72. The electrical stimulation used according to Example 71, wherein the location of one or more electrodes is determined by: stimulating multiple contact points in a subject to target at least one muscle in a body region of a subject with motor impairment due to SMA; measuring electrical activity associated with said muscle in response to stimulation; and identifying one or more of the multiple contact points as the location of the electrodes based on said electrical activity.

[0369] Example 73. Electrical stimulation used according to any of the foregoing examples, wherein at least one of one or more electrodes is placed percutaneously.

[0370] Example 74. Electrical stimulation used according to any of the foregoing examples, wherein at least one of one or more electrodes is implanted.

[0371] Example 75. Use of one or more electrodes controlled by a neurostimulator in the manufacture of a medicament for treating a subject with SMA, wherein the one or more electrodes controlled by the neurostimulator are configured to apply a therapeutically effective amount of electrical stimulation to sensory neurons innervating a body region of the subject that has motor impairment due to SMA.

[0372] Example 76. According to the use described in Example 75, the application of electrical stimulation increases the probability of activation of spinal motor neurons in body regions innervated by subjects with motor impairment due to SMA.

[0373] Example 77. The use according to Example 75 or Example 76, wherein stimulation is applied at or below the motor threshold such that the stimulation does not directly cause movement and / or muscle activity in the body regions of a subject with motor impairment due to SMA.

[0374] Example 78. According to the use described in Examples 75 to 77, the electrical stimulation comprises an electrical pulse having an amplitude of about 10 µA to about 100 mA, a width between about 40 µs and about 2 ms, and a frequency of about 10 Hz to about 2000 Hz.

[0375] Example 79. According to the use described in Examples 75 to 78, the electrical stimulation comprises an electrical pulse having an amplitude of about 10 µA to about 10 mA, a width between about 40 µs and about 2 ms, and a frequency of about 10 Hz to about 1000 Hz.

[0376] Example 80. According to the use described in Examples 75 to 79, the electrical stimulation comprises an electrical pulse having an amplitude of about 100 µA to about 10 mA, a width between about 40 µs and about 500 µs, and a frequency of about 10 Hz to about 1000 Hz.

[0377] Example 81. The use according to any one of the foregoing embodiments, wherein the electrical stimulation comprises a stimulation pattern of 2 to 5 pulses separated by a pulse interval of about 3 ms to about 10 ms, and wherein the series is repeated at a frequency of about 10 Hz to about 100 Hz.

[0378] Example 82. According to the use described in Example 81, the stimulation pattern is a series of 3 pulses separated by a pulse interval of about 5 ms, wherein the series is repeated at a frequency of about 30 to about 100 Hz, and wherein the pulse width is about 200 µs.

[0379] Example 83. The use according to any one of Examples 78 to 82, wherein the pulse is a cathode-preferred biphase or single-phase charge balance pulse.

[0380] Example 84. The use according to any one of the foregoing examples, wherein electrical stimulation is applied for at least 2 hours / day during a period of at least 6 months.

[0381] Example 85. The use according to any one of Examples 75 to 83, wherein electrical stimulation is applied for at least 1 hour / day during a period of at least 1 month.

[0382] Example 86. The use according to any one of the foregoing examples, wherein one or more electrodes are contained within an array of independently controllable electrodes implanted in the subject.

[0383] Example 87. The application according to Example 86, wherein the electrode array is a multi-electrode paddle array.

[0384] Example 88. The use according to any one of the foregoing examples, wherein one or more electrodes are epidurally implanted in the spinal cord of a subject.

[0385] Example 89. The use according to any one of Examples 75 to 88, wherein one or more electrodes are implanted at the dorsal root of one or more sensory neurons in a body region innervating a subject with motor impairment.

[0386] Example 90. The use according to any one of Examples 75 to 88, wherein one or more electrodes are implanted in the dorsolateral position of the spinal cord adjacent to the dorsal root of one or more sensory neurons innervating a body region of the subject with motor impairment.

[0387] Example 91. The use according to any one of Examples 75 to 87, wherein one or more electrodes are implanted at the dorsal root ganglion of one or more sensory neurons in a body region innervating a subject with motor impairment.

[0388] Example 92. The use according to any one of Examples 75 to 86, wherein one or more electrodes are contained in a sleeve surrounding a peripheral nerve containing sensory neurons innervating a body region of a subject with motor impairment due to SMA.

[0389] Example 93. The use according to any one of Examples 75 to 86, wherein one or more electrodes penetrate peripheral nerves or dorsal root ganglia containing sensory neurons innervating a body region of a subject with motor impairment due to SMA.

[0390] Example 94. The use according to any one of the preceding examples, wherein the subject’s body region is selected from at least one of the following: lower back, hip, leg, ankle and foot; and one or more electrodes are implanted in the dorsolateral position of the spinal cord and across one or more of the T11-S1 nerve roots.

[0391] Example 95. The use according to any one of the preceding examples, wherein the subject's body region is selected from at least one of the following: upper arm, shoulder, arm, hand, and respiratory muscles; and one or more electrodes are implanted in the dorsolateral aspect of the spinal cord and across one or more of the C3-T2 nerve roots.

[0392] Example 96. The use according to any one of the preceding examples, wherein the subject's body region is selected from at least one of the following: chest, chest wall, abdomen, upper back, and mid-back; and one or more electrodes are implanted in the dorsolateral aspect of the spinal cord and across one or more of the T3-T10 nerve roots.

[0393] Example 97. The use according to any one of the foregoing embodiments, wherein the neurostimulator is an external or implantable pulse generator.

[0394] Example 98. The use according to any one of the foregoing examples, wherein the neurostimulator is implanted in the subject.

[0395] Example 99. The use according to any one of the foregoing examples, wherein a subject suffering from SMA is selected for treatment.

[0396] Example 100. The use according to any one of the foregoing examples, wherein the sports injury includes partial or complete paralysis, loss of dexterity, loss of muscle strength and / or uncontrollable muscle tension.

[0397] Example 101. The use according to any one of the foregoing embodiments, wherein the location of one or more electrodes is selected based on the body region of the subject with motor injury due to SMA.

[0398] Example 102. According to the use described in Example 101, the location of one or more electrodes is determined by: stimulating a plurality of contact points in a subject to target at least one muscle in a body region of a subject with motor impairment due to SMA; measuring electrical activity associated with the muscle in response to the stimulation; and identifying one or more of the plurality of contact points as the location of the electrodes based on the electrical activity.

[0399] Example 103. The use according to any one of the foregoing embodiments, wherein at least one of the one or more electrodes is placed percutaneously.

[0400] Example 104. The use according to any one of the foregoing examples, wherein at least one of one or more electrodes is implanted.

[0401] Example 105. Use of one or more electrodes controlled by a neurostimulator in the manufacture of a medicament for treating a subject with SMA, wherein the one or more electrodes controlled by the neurostimulator are used to apply electrical stimulation to sensory neurons innervating a body region of the subject that has motor impairment due to SMA.

[0402] Example 106. According to the use described in Example 105, the application of electrical stimulation increases the probability of activation rate of spinal motor neurons innervating body regions of a subject with motor impairment due to SMA.

[0403] Example 107. The use according to Example 105 or Example 106, wherein stimulation is applied at or below a motion threshold such that the stimulation does not directly cause movement and / or muscle activity in the body regions of a subject with motor impairment due to SMA.

[0404] Example 108. According to the use described in Examples 105 to 107, the electrical stimulation comprises an electrical pulse having an amplitude of about 10 µA to about 100 mA, a width between about 40 µs and about 2 ms, and a frequency of about 10 Hz to about 2000 Hz.

[0405] Example 109. According to the use described in Examples 105 to 108, the electrical stimulation comprises an electrical pulse having an amplitude of about 10 µA to about 10 mA, a width between about 40 µs and about 2 ms, and a frequency of about 10 Hz to about 1000 Hz.

[0406] Example 110. The use according to Examples 105 to 109, wherein the electrical stimulation comprises an electrical pulse having an amplitude of about 100 µA to about 10 mA, a width between about 40 µs and about 500 µs, and a frequency of about 10 Hz to about 1000 Hz.

[0407] Example 111. The use according to any one of the foregoing embodiments, wherein the electrical stimulation comprises a stimulation pattern of 2 to 5 pulses separated by a pulse interval of about 3 ms to about 10 ms, and wherein the series is repeated at a frequency of about 10 Hz to about 100 Hz.

[0408] Example 112. According to the use described in Example 111, the stimulation pattern is a series of 3 pulses separated by a pulse interval of about 5 ms, wherein the series is repeated at a frequency of about 30 to about 100 Hz, and wherein the pulse width is about 200 µs.

[0409] Example 113. The use according to any one of Examples 108 to 112, wherein the pulse is a cathode-preferred biphase or single-phase charge balance pulse.

[0410] Example 114. The use according to any one of the foregoing examples, wherein electrical stimulation is applied for at least 2 hours / day during a period of at least 6 months.

[0411] Example 115. The use according to any one of Examples 105 to 113, wherein electrical stimulation is applied for at least 1 hour / day during a period of at least 1 month.

[0412] Example 116. The use according to any one of the foregoing examples, wherein one or more electrodes are contained within an array of independently controllable electrodes implanted in the subject.

[0413] Example 117. The application according to Example 116, wherein the electrode array is a multi-electrode paddle array.

[0414] Example 118. The use according to any one of the foregoing examples, wherein one or more electrodes are epidurally implanted in the spinal cord of a subject.

[0415] Example 119. The use according to any one of Examples 105 to 118, wherein one or more electrodes are implanted at the dorsal root of one or more sensory neurons in a body region innervating a subject with motor impairment.

[0416] Example 120. The use according to any one of Examples 105 to 118, wherein one or more electrodes are implanted in the dorsolateral position of the spinal cord adjacent to the dorsal root of one or more sensory neurons innervating a body region of the subject with motor impairment.

[0417] Example 121. The use according to any one of Examples 105 to 117, wherein one or more electrodes are implanted at the dorsal root ganglion of one or more sensory neurons in a body region innervating a subject with motor impairment.

[0418] Example 122. The use according to any one of Examples 105 to 116, wherein one or more electrodes are contained in a sleeve surrounding a peripheral nerve containing sensory neurons innervating a body region of a subject with motor impairment due to SMA.

[0419] Example 123. The use according to any one of Examples 105 to 116, wherein one or more electrodes penetrate peripheral nerves or dorsal root ganglia containing sensory neurons innervating a body region of a subject with motor impairment due to SMA.

[0420] Example 124. The use according to any of the preceding examples, wherein the subject’s body region is selected from at least one of the following: lower back, hip, leg, ankle and foot; and one or more electrodes are implanted in the dorsolateral position of the spinal cord and across one or more of the T11-S1 nerve roots.

[0421] Example 125. The use according to any one of the preceding examples, wherein the subject's body region is selected from at least one of the following: upper arm, shoulder, arm, hand, and respiratory muscles; and one or more electrodes are implanted in the dorsolateral aspect of the spinal cord and across one or more of the C3-T2 nerve roots.

[0422] Example 126. The use according to any one of the preceding examples, wherein the subject's body region is selected from at least one of the following: chest, chest wall, abdomen, upper back, and mid-back; and one or more electrodes are implanted in the dorsolateral aspect of the spinal cord and across one or more of the T3-T10 nerve roots.

[0423] Example 127. The use according to any one of the foregoing examples, wherein the neurostimulator is an external or implantable pulse generator.

[0424] Example 128. The use according to any one of the foregoing examples, wherein a neurostimulator is implanted in the subject.

[0425] Example 129. The use according to any one of the foregoing examples, wherein a subject suffering from SMA is selected for treatment.

[0426] Example 130. The use according to any one of the foregoing examples, wherein the sports injury includes partial or complete paralysis, loss of dexterity, loss of muscle strength and / or uncontrollable muscle tension.

[0427] Example 131. The use according to any one of the foregoing embodiments, wherein the location of one or more electrodes is selected based on the body region of the subject with motor injury due to SMA.

[0428] Example 132. According to the use described in Example 131, the location of one or more electrodes is determined by: stimulating a plurality of contact points in a subject to target at least one muscle in a body region of a subject with motor impairment due to SMA; measuring electrical activity associated with the muscle in response to the stimulation; and identifying one or more of the plurality of contact points as the location of the electrodes based on the electrical activity.

[0429] Example 133. The use according to any one of the foregoing embodiments, wherein at least one of the one or more electrodes is placed percutaneously.

[0430] Example 134. The use according to any one of the foregoing examples, wherein at least one of one or more electrodes is implanted.

[0431] Example 135. The method according to any one of Examples 1 to 44, wherein the subject is receiving SMA therapy in conjunction with the electrical stimulation.

[0432] Example 136. The method according to Example 135, wherein the SMA therapy is selected from the group consisting of: vector-based gene therapy that delivers a copy of the SMN1 gene; antisense oligonucleotide (ASO) therapy that targets the SMN2 gene; or small molecule SMN2 splicing regulators.

[0433] Example 137. The method according to Example 135 or 136, wherein the SMA therapy is sovalprevir, nusinersen, or liscprehyn.

[0434] Example 138. The method according to any one of Examples 135 to 137, wherein sovalrevir is administered to the subject within 6 years prior to the first application of electrical stimulation.

[0435] Example 139. The method according to any one of Examples 135 to 137, wherein sovalrevir is administered to the subject at least 18 months prior to the first application of electrical stimulation.

[0436] Example 140. The method according to any one of Examples 135 to 137, wherein the subject is receiving nusinersen according to a maintenance dosing regimen during electrical stimulation.

[0437] Example 141. The method according to any one of Examples 135 to 137 or 140, wherein nusinersen is first administered to the subject at least 6 months prior to the first application of electrical stimulation.

[0438] Example 142. The method according to any one of Examples 135 to 137, wherein the subject is receiving lisclan.

[0439] Example 143. The method according to any one of Examples 135 to 137 or 142, wherein the subject begins administration of lisclan within 18 months prior to the first application of electrical stimulation.

[0440] Example 144. The method according to any one of Examples 135 to 137 or 142, wherein the subject has been given lisclan for at least 1 year prior to the first application of electrical stimulation.

[0441] Example 145. Electrical stimulation as described in any one of Examples 45 to 74, wherein the subject is receiving SMA therapy in conjunction with said electrical stimulation.

[0442] Example 146. The electrical stimulation used according to Example 145, wherein the SMA therapy is selected from the group consisting of: vector-based gene therapy that delivers a copy of the SMN1 gene; antisense oligonucleotide (ASO) therapy that targets the SMN2 gene; or a small molecule SMN2 splicing modulator.

[0443] Example 147. Electrical stimulation used according to Example 145 or 146, wherein the SMA therapy is sovalprevir, nusinersen, or liscprehyn.

[0444] Example 148. The electrical stimulation used according to any one of Examples 145 to 147, wherein sovalrevir was administered to the subject within 6 years prior to the first application of electrical stimulation.

[0445] Example 149. Electrical stimulation as described in any one of Examples 145 to 147, wherein sovalrevir was administered to the subject at least 18 months prior to the first application of electrical stimulation.

[0446] Example 150. Electrical stimulation as described in any one of Examples 145 to 147, wherein the subject is receiving nusinersen according to a maintenance dosing regimen during electrical stimulation.

[0447] Example 151. Electrical stimulation as described in any one of Examples 145 to 147 or 150, wherein nusinersen is first administered to the subject at least 6 months prior to the first application of electrical stimulation.

[0448] Example 152. Electrical stimulation as described in any one of Examples 145 to 147, wherein the subject is receiving lispurinol.

[0449] Example 153. Electrical stimulation as described in any one of Examples 145 to 147 or 152, wherein the subject began taking lisclan within 18 months prior to the first application of electrical stimulation.

[0450] Example 154. The electrical stimulation used according to any one of Examples 145 to 147 or 152, wherein the subject has been given lispurane for at least 1 year prior to the first application of electrical stimulation.

[0451] Example 155. The use according to any one of Examples 75 to 134, wherein the subject is receiving SMA therapy in combination with electrical stimulation.

[0452] Example 156. The use according to Example 155, wherein the SMA therapy is selected from the group consisting of: vector-based gene therapy that delivers a copy of the SMN1 gene; antisense oligonucleotide (ASO) therapy that targets the SMN2 gene; or small molecule SMN2 splicing regulators.

[0453] Example 157. The use according to Example 155 or 156, wherein the SMA therapy is sovalprevir, nusinersen, or liscprehyn.

[0454] Example 158. Use according to any one of Examples 155 to 157, wherein sovalrevir is administered to the subject within 6 years prior to the first application of electrical stimulation.

[0455] Example 159. Use according to any one of Examples 155 to 157, wherein sovalrevir is administered to the subject at least 18 months prior to the first application of electrical stimulation.

[0456] Example 160. Use according to any one of Examples 155 to 157, wherein the subject is receiving nusinersen according to a maintenance dosing regimen during electrical stimulation.

[0457] Example 161. The use according to any one of Examples 155 to 157 or 160, wherein nusinersen is first administered to the subject at least 6 months prior to the first application of electrical stimulation.

[0458] Example 162. Use according to any one of Examples 155 to 157, wherein the subject is receiving liscperane.

[0459] Example 163. Use according to any one of Examples 155 to 157 or 162, wherein the subject begins administration of lisclan within 18 months prior to the first application of electrical stimulation.

[0460] Example 164. The use according to any one of Examples 155 to 157 or 162, wherein the subject has been given lisclan for at least 1 year prior to the first application of electrical stimulation.

[0461] Example 165. The method according to any one of Examples 1 to 44 or 135 to 144, wherein the subject has type 1 SMA.

[0462] Example 166. The method according to any one of Examples 1 to 44 or 135 to 144, wherein the subject has type 2 SMA.

[0463] Example 167. The method according to any one of Examples 1 to 44 or 135 to 144, wherein the subject has type 3 SMA.

[0464] Example 168. The method according to any one of Examples 1 to 44 or 135 to 144, wherein the subject has type 4 SMA.

[0465] Example 169. Electrical stimulation used according to any one of Examples 45 to 74 or 145 to 154, wherein the subject has type 1 SMA.

[0466] Example 170. Electrical stimulation used according to any one of Examples 45 to 74 or 145 to 154, wherein the subject has type 2 SMA.

[0467] Example 171. Electrical stimulation used according to any one of Examples 45 to 74 or 145 to 154, wherein the subject has type 3 SMA.

[0468] Example 172. Electrical stimulation used according to any one of Examples 45 to 74 or 145 to 154, wherein the subject has type 4 SMA.

[0469] Example 173. The use according to any one of Examples 75 to 134 or 155 to 164, wherein the subject has type 1 SMA.

[0470] Example 174. The use according to any one of Examples 75 to 134 or 155 to 164, wherein the subject has type 2 SMA.

[0471] Example 175. The use according to any one of Examples 75 to 134 or 155 to 164, wherein the subject has type 3 SMA.

[0472] Example 176. The use according to any one of Examples 75 to 134 or 155 to 164, wherein the subject has type 4 SMA.

[0473] Example 177. A method for treating spinal muscular atrophy (SMA) in a subject, the method comprising:

[0474] A therapeutically effective amount of electrical stimulation is applied to one or more sensory neurons in a body region innervated by a subject with motor impairment due to SMA.

[0475] The subjects were receiving SMA therapy in conjunction with the electrical stimulation.

[0476] Example 178. A method for stimulating one or more motor neurons damaged by SMA, the method comprising:

[0477] Electrical stimulation is applied to at least one of the motor neurons, wherein the motor neuron innervates a body area of ​​the subject who has motor impairment due to SMA;

[0478] The subjects were receiving SMA therapy in conjunction with the electrical stimulation.

[0479] Example 179. A method for increasing the firing rate of one or more motor neurons damaged by SMA in a subject, the method comprising:

[0480] Electrical stimulation is applied to one or more sensory neurons in a body region that innervates the subject.

[0481] The subjects were receiving SMA therapy in combination with electrical stimulation;

[0482] This increases the activation rate of one or more motor neurons in the subject that have been damaged by SMA.

[0483] Example 180. The method according to any one of Examples 177 to 179, wherein the SMA therapy is selected from the group consisting of: vector-based gene therapy that delivers a copy of the SMN1 gene; antisense oligonucleotide (ASO) therapy that targets the SMN2 gene; or small molecule SMN2 splicing regulators.

[0484] Example 181. The method according to any one of Examples 177 to 180, wherein the SMA therapy is sovalprevir, nusinersen, or liscprehyn.

[0485] Example 182. The method according to any one of Examples 177 to 181, wherein the subject's body region is selected from at least one of the following: lower back, hip, leg, ankle, and foot.

[0486] Example 183. The method according to any one of Examples 177 to 182, wherein one or more electrodes are implanted in the dorsolateral position of the spinal cord and across one or more of the T11-S1 nerve roots; and electrical stimulation is provided through one or more of the one or more electrodes.

[0487] Example 184. The method according to any one of Examples 177 to 180, wherein the body region of the subject is selected from at least one of the following: upper arm, shoulder, arm, hand, and respiratory muscles.

[0488] Example 185. The method according to any one of Examples 177 to 180 or 184, wherein one or more electrodes are implanted in a dorsolateral position of the spinal cord and across one or more of the C3-T2 nerve roots; and electrical stimulation is provided through one or more of the one or more electrodes.

[0489] Example 186. The method according to any one of Examples 177 to 180, wherein the body region of the subject is selected from at least one of the following: chest, chest wall, abdomen, upper back, and mid-back.

[0490] Example 187. The method according to any one of Examples 177 to 180 or 186, wherein one or more electrodes are implanted in a dorsolateral position of the spinal cord and across one or more of the T3-T10 nerve roots; and electrical stimulation is provided through one or more of the one or more electrodes.

[0491] Example 188. The method according to any one of Examples 177 to 187, wherein the activation rate of spinal motor neurons in the body regions innervated by the subject with motor impairment due to SMA is increased.

[0492] Example 189. The method according to any one of Examples 177 to 188, wherein the subject has increased joint torque and muscle strength in the body region.

[0493] Example 190. The method according to any one of Examples 177 to 189, wherein electrical stimulation is applied for at least 1 hour / day during a period of at least 1 month.

[0494] Example 191. The method according to any one of Examples 177 to 190, wherein a stimulus is applied at or below a motion threshold such that the stimulus does not directly cause movement and / or muscle activity in a body region of a subject with motor impairment due to SMA.

[0495] Example 192. The method according to any one of Examples 177 to 191, wherein the electrical stimulation comprises an electrical pulse having an amplitude of about 10 µA to about 100 mA, a width between about 40 µs and about 2 ms, and a frequency of about 10 Hz to about 2000 Hz.

[0496] Example 193. The method according to any one of Examples 177 to 192, wherein the sports injury includes partial or complete paralysis, loss of dexterity, loss of muscle strength and / or uncontrollable muscle tension.

[0497] Example 194. The method according to any one of Examples 177 to 193, wherein the subject has type 1 SMA.

[0498] Example 195. The method according to any one of Examples 177 to 194, wherein the subject has type 2 SMA.

[0499] Example 196. The method according to any one of Examples 177 to 194, wherein the subject has type 3 SMA.

[0500] Example 197. The method according to any one of Examples 177 to 194, wherein the subject has type 4 SMA.

[0501] Example 198. The method according to any one of Examples 177 to 197, wherein the SMA therapy is nusinersen.

[0502] Example 199. The method according to any one of Examples 177 to 198, wherein the SMA therapy is liscperane.

[0503] Example 200. An electrical stimulation for use in treating a subject with spinal muscular atrophy (SMA), wherein a therapeutically effective amount of the electrical stimulation is applied to one or more sensory neurons innervating a body region of the subject that has motor impairment due to SMA; and wherein the subject is receiving SMA therapy in conjunction with the electrical stimulation.

[0504] Example 201. An electrical stimulation for use in stimulating one or more motor neurons damaged by SMA, wherein the electrical stimulation is applied to at least one of the motor neurons, wherein the motor neuron innervates a body area of ​​a subject with motor impairment due to SMA; and wherein the subject is receiving SMA therapy in conjunction with the electrical stimulation.

[0505] Example 202. An electrical stimulation for use in increasing the activation rate of one or more motor neurons damaged by SMA in a subject, wherein the electrical stimulation is applied to one or more sensory neurons innervating a body region of the subject; wherein the subject is receiving SMA therapy in conjunction with the electrical stimulation; thereby increasing the activation rate of the subject's motor neurons.

[0506] Example 203. The electrical stimulation used according to any one of Examples 200 to 202, wherein the SMA therapy is selected from the group consisting of: vector-based gene therapy that delivers a copy of the SMN1 gene; antisense oligonucleotide (ASO) therapy that targets the SMN2 gene; or a small molecule SMN2 splicing modulator.

[0507] Example 204. Electrical stimulation used according to any one of Examples 200 to 203, wherein the SMA therapy is sovalprevir, nusinersen, or lisporalen.

[0508] Example 205. Electrical stimulation used according to any one of Examples 200 to 204, wherein the subject's body area is selected from at least one of the following: lower back, hip, leg, ankle, and foot.

[0509] Example 206. The electrical stimulation used according to any one of Examples 200 to 205, wherein the electrical stimulation is provided by one or more electrodes implanted in the dorsolateral aspect of the spinal cord and across one or more of the T11-S1 nerve roots.

[0510] Example 207. Electrical stimulation used according to any one of Examples 200 to 204, wherein the subject's body area is selected from at least one of the following: upper arm, shoulder, arm, hand, and respiratory muscles.

[0511] Example 208. Electrical stimulation as described in any one of Examples 200 to 204 or 207, wherein the electrical stimulation is provided by one or more electrodes implanted in the dorsolateral aspect of the spinal cord and across one or more of the C3-T2 nerve roots.

[0512] Example 209. Electrical stimulation used according to any one of Examples 200 to 204, wherein the subject's body region is selected from at least one of the following: chest, chest wall, abdomen, upper back, and mid-back.

[0513] Example 210. The electrical stimulation used according to any one of Examples 200 to 204 or 209, wherein the electrical stimulation is provided by one or more electrodes implanted in the dorsolateral position of the spinal cord and across one or more of the T3-T10 nerve roots.

[0514] Example 211. Electrical stimulation used according to any one of Examples 200 to 210, wherein the activation rate of spinal motor neurons in the body regions innervated by the subject with motor injury due to SMA is increased.

[0515] Example 212. Electrical stimulation used according to any one of Examples 200 to 211, wherein the subject experiences an increase in joint torque and muscle strength in a body region.

[0516] Example 213. The electrical stimulation used according to any one of Examples 200 to 212, wherein the electrical stimulation is applied for at least 1 hour / day during a period of at least 1 month.

[0517] Example 214. Electrical stimulation used according to any one of Examples 200 to 213, wherein stimulation is applied at or below a motor threshold such that the stimulation does not directly cause movement and / or muscle activity in that body area of ​​a subject with motor impairment due to SMA.

[0518] Example 215. The electrical stimulation used according to any one of Examples 200 to 214, wherein the electrical stimulation comprises an electrical pulse having an amplitude of about 10 µA to about 100 mA, a width between about 40 µs and about 2 ms, and a frequency of about 10 Hz to about 2000 Hz.

[0519] Example 216. Electrical stimulation used according to any one of Examples 200 to 215, wherein the motor injury includes partial or complete paralysis, loss of dexterity, loss of muscle strength and / or uncontrollable muscle tension.

[0520] Example 217. Electrical stimulation used according to any one of Examples 200 to 216, wherein the subject has type 1 SMA.

[0521] Example 218. Electrical stimulation used according to any one of Examples 200 to 216, wherein the subject has type 2 SMA.

[0522] Example 219. Electrical stimulation used according to any one of Examples 200 to 216, wherein the subject has type 3 SMA.

[0523] Example 220. Electrical stimulation used according to any one of Examples 200 to 216, wherein the subject has type 4 SMA.

[0524] Example 221. Electrical stimulation used according to any one of Examples 200 to 220, wherein the SMA therapy is nusinersen.

[0525] Example 222. Electrical stimulation used according to any one of Examples 200 to 220, wherein the SMA therapy is liscperane.

[0526] Example 223. An electrode assembly comprising one or more electrodes configured to provide electrical stimulation for use according to any one of Examples 200 to 222.

[0527] Example 224. An electrode assembly according to Example 223, wherein one or more electrodes comprise a multi-electrode paddle array.

[0528] Example 224. The electrode assembly according to Example 222 or 223 further includes a neurostimulator for controlling one or more electrodes.

[0529] Example 225. An electrode assembly according to any one of Examples 222 to 224, wherein one or more electrodes are epidurally implanted in the spinal cord of a subject.

[0530] Example 226. An electrode assembly according to any one of claims 222 to 225, wherein one or more electrodes are implanted at the dorsal root of one or more sensory neurons in a body region innervating a subject with motor impairment.

[0531] For purposes of explanation, the foregoing description has been illustrated with reference to specific examples. However, the illustrative discussion above is not intended to be exhaustive or to limit the invention to the precise forms disclosed. In view of the foregoing teachings, many modifications and variations are possible. These examples were chosen and described in order to best explain the principles of these techniques and their practical applications. Thus, those skilled in the art can best utilize these techniques and various examples with various modifications suitable for the particular intended use.

[0532] It is obvious that the precise details of the described method or composition may be altered or modified without departing from the spirit of the described embodiments. All such modifications and variations falling within the scope and spirit of the following claims are protected.

Claims

1. A method for treating a subject with spinal muscular atrophy (SMA), the method comprising: A therapeutically effective amount of electrical stimulation is applied to one or more sensory neurons in the body region of the subject that innervates motor impairment due to SMA. The subjects in the study were receiving SMA therapy in conjunction with the electrical stimulation.

2. A method for stimulating one or more motor neurons damaged by SMA, the method comprising: Electrical stimulation is applied to at least one of the motor neurons, wherein the motor neuron innervates a body area of ​​the subject who has motor impairment due to SMA; The subjects in the study were receiving SMA therapy in conjunction with the electrical stimulation.

3. A method for increasing the firing rate of one or more motor neurons damaged by SMA in a subject, the method comprising: Electrical stimulation is applied to one or more sensory neurons in a body region that innervates the subject. The subjects mentioned therein were receiving SMA therapy in conjunction with the electrical stimulation; This increases the firing rate of the one or more motor neurons in the subject that are damaged by SMA.

4. The method according to any one of claims 1 to 3, wherein the SMA therapy is selected from the group consisting of: vector-based gene therapy that delivers a copy of the SMN1 gene; antisense oligonucleotide (ASO) therapy that targets the SMN2 gene; or small molecule SMN2 splicing regulators.

5. The method according to any one of claims 1 to 4, wherein the SMA therapy is sovalprevir, nusinersen, or liscprehyn.

6. The method according to any one of claims 1 to 5, wherein the body region of the subject is selected from at least one of the following: lower back, hip, leg, ankle, and foot.

7. The method according to any one of claims 1 to 6, wherein one or more electrodes are implanted in a dorsolateral position of the spinal cord and across one or more of the T11-S1 nerve roots; and the electrical stimulation is provided through one or more of the one or more electrodes.

8. The method according to any one of claims 1 to 5, wherein the body region of the subject is selected from at least one of the following: upper arm, shoulder, arm, hand, and respiratory muscles.

9. The method according to any one of claims 1 to 5 or 8, wherein one or more electrodes are implanted in a dorsolateral position of the spinal cord and across one or more of the C3-T2 nerve roots; and the electrical stimulation is provided through one or more of the one or more electrodes.

10. The method according to any one of claims 1 to 5, wherein the body region of the subject is selected from at least one of the following: chest, chest wall, abdomen, upper back, and mid-back.

11. The method according to any one of claims 1 to 5 or 10, wherein one or more electrodes are implanted in a dorsolateral position of the spinal cord and across one or more of the T3-T10 nerve roots; and the electrical stimulation is provided through one or more of the one or more electrodes.

12. The method according to any one of claims 1 to 11, wherein the probability of activation rate of spinal motor neurons in the body region of the subject having the motor injury due to SMA is increased.

13. The method according to any one of claims 1 to 12, wherein the subject has increased joint torque and muscle strength in the body region.

14. The method according to any one of claims 1 to 13, wherein the electrical stimulation is applied for at least 1 hour / day during a period of at least 1 month.

15. The method according to any one of claims 1 to 14, wherein the stimulus is applied at or below a motion threshold such that the stimulus does not directly cause movement and / or muscle activity in the body region of the subject who has the motion injury due to SMA.

16. The method according to any one of claims 1 to 14, wherein the electrical stimulation comprises an electrical pulse having an amplitude of about 10 µA to about 100 mA, a width between about 40 µs and about 2 ms, and a frequency of about 10 Hz to about 2000 Hz.

17. The method according to any one of claims 1 to 16, wherein the motor injury includes partial or complete paralysis, loss of dexterity, loss of muscle strength and / or uncontrollable muscle tension.

18. The method according to any one of claims 1 to 17, wherein the subject suffers from type 1 SMA.

19. The method according to any one of claims 1 to 17, wherein the subject has type 2 SMA.

20. The method according to any one of claims 1 to 17, wherein the subject suffers from type 3 SMA.

21. The method according to any one of claims 1 to 17, wherein the subject suffers from type 4 SMA.

22. The method according to any one of claims 1 to 21, wherein the SMA therapy is nusinersen.

23. The method according to any one of claims 1 to 21, wherein the SMA therapy is liscprostol.

24. An electrical stimulation for use in treating a subject with spinal muscular atrophy (SMA), wherein a therapeutically effective amount of the electrical stimulation is applied to one or more sensory neurons innervating a body region of the subject that has motor impairment due to SMA; and wherein the subject is receiving SMA therapy in conjunction with the electrical stimulation.

25. An electrical stimulation for use in stimulating one or more motor neurons damaged by SMA, wherein the electrical stimulation is applied to at least one of the motor neurons, wherein the motor neurons innervate a body area of ​​a subject with motor impairment due to SMA; and wherein the subject is receiving SMA therapy in conjunction with the electrical stimulation.

26. An electrical stimulation for use in increasing the activation rate of one or more motor neurons damaged by SMA in a subject, wherein the electrical stimulation is applied to one or more sensory neurons in a body region innervating the subject; wherein the subject is receiving SMA therapy in conjunction with the electrical stimulation; thereby increasing the activation rate of the subject's motor neurons.

27. The electrical stimulation used according to any one of claims 24 to 26, wherein the SMA therapy is selected from the group consisting of: vector-based gene therapy that delivers a copy of the SMN1 gene; antisense oligonucleotide (ASO) therapy that targets the SMN2 gene; or small molecule SMN2 splicing modulators.

28. The electrical stimulation used according to any one of claims 24 to 27, wherein the SMA therapy is sovalprevir, nusinersen, or lisperam.

29. The electrical stimulation used according to any one of claims 24 to 28, wherein the body region of the subject is selected from at least one of the following: lower back, hip, leg, ankle, and foot.

30. The electrical stimulation used according to any one of claims 24 to 29, wherein the electrical stimulation is provided by one or more electrodes implanted in the dorsolateral aspect of the spinal cord and across one or more of the T11-S1 nerve roots.

31. The electrical stimulation used according to any one of claims 24 to 28, wherein the body region of the subject is selected from at least one of the following: upper arm, shoulder, arm, hand, and respiratory muscles.

32. The electrical stimulation used according to any one of claims 24 to 28 or 31, wherein the electrical stimulation is provided by one or more electrodes implanted in the dorsolateral aspect of the spinal cord and across one or more of the C3-T2 nerve roots.

33. The electrical stimulation used according to any one of claims 24 to 28, wherein the body region of the subject is selected from at least one of the following: chest, chest wall, abdomen, upper back, and mid-back.

34. The electrical stimulation used according to any one of claims 24 to 28 or 33, wherein the electrical stimulation is provided by one or more electrodes implanted in the dorsolateral aspect of the spinal cord and across one or more of the T3-T10 nerve roots.

35. The electrical stimulation used according to any one of claims 24 to 34, wherein the probability of activation of spinal motor neurons innervating the body region of the subject with said motor injury due to SMA is increased.

36. The electrical stimulation used according to any one of claims 24 to 35, wherein the subject has increased joint torque and muscle strength in the body region.

37. The electrical stimulation used according to any one of claims 24 to 36, wherein the electrical stimulation is applied for at least 1 hour / day during a period of at least 1 month.

38. The electrical stimulation used according to any one of claims 24 to 37, wherein the stimulation is applied at or below a motor threshold such that the stimulation does not directly cause movement and / or muscle activity in the body area of ​​the subject who has the motor injury due to SMA.

39. The electrical stimulation used according to any one of claims 24 to 38, wherein the electrical stimulation comprises an electrical pulse having an amplitude of about 10 µA to about 100 mA, a width between about 40 µs and about 2 ms, and a frequency of about 10 Hz to about 2000 Hz.

40. The electrical stimulation used according to any one of claims 24 to 39, wherein the motor injury includes partial or complete paralysis, loss of dexterity, loss of muscle strength and / or uncontrollable muscle tension.

41. The electrical stimulation used according to any one of claims 24 to 40, wherein the subject suffers from type 1 SMA.

42. The electrical stimulation used according to any one of claims 24 to 40, wherein the subject suffers from type 2 SMA.

43. The electrical stimulation used according to any one of claims 24 to 40, wherein the subject suffers from type 3 SMA.

44. The electrical stimulation used according to any one of claims 24 to 40, wherein the subject suffers from type 4 SMA.

45. The electrical stimulation used according to any one of claims 24 to 44, wherein the SMA therapy is nusinersen.

46. ​​The electrical stimulation used according to any one of claims 24 to 44, wherein the SMA therapy is lisclan.

47. An electrode assembly comprising one or more electrodes configured to provide electrical stimulation for use as described in any one of claims 24 to 46.

48. The electrode assembly of claim 47, wherein the one or more electrodes comprise a multi-electrode paddle array.

49. The electrode assembly according to claim 47 or 48, further comprising a neurostimulator for controlling the one or more electrodes.

50. The electrode assembly according to any one of claims 47 to 49, wherein the one or more electrodes are epidurally implanted in the spinal cord of the subject.

51. The electrode assembly according to any one of claims 47 to 50, wherein the one or more electrodes are implanted at the dorsal root of the one or more sensory neurons in the body region innervating the subject and having the motor injury.

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