An implantable selective spinal nerve root stimulation system

Abstract

The present invention relates to an implantable selective spinal nerve root stimulation system, which comprises: a stimulator, which is used to generate an electrical stimulation signal with a frequency, pulse width and intensity, at least one stimulation electrode, which has a stimulation contact at the distal end, and these stimulation electrodes extend toward the head end along the direction of the cauda equina nerve, pass through the dura mater sac area in the midline, pass through the skin from the inside to the outside through the interspinous process gap, or are directly connected to the stimulator along a subcutaneous tunnel. The stimulation contacts carried by the stimulation electrodes are elastically fixed to the free dorsal root nerve area in an embracing manner, wherein the resistance from the stimulation contacts to the cerebrospinal fluid is greater than the resistance between the stimulation contacts and the outer membrane of the dorsal root nerve where they are elastically fixed. The present invention can solve the problem that the existing stimulation electrodes, the spinal cord and the dorsal nerve roots have defects such as poor reliability, great influence of the patient's body position, and high power consumption due to the presence of cerebrospinal fluid of different thicknesses, and cannot effectively promote the recovery of lower limb function of paraplegia after high spinal cord injury.

Description

Technical Field

[0001] The invention relates to the technical field of electronic medical treatment, and in particular to a spinal nerve root stimulation system, and in particular to an implantable selective spinal nerve root stimulation system. Background Art

[0002] Traditional treatments for spinal cord injury include medication, physical therapy, and rehabilitation training. Drugs are mainly used to relieve pain and reduce inflammation, but they cannot repair damaged nerve tissue. The effect of physical therapy depends largely on the patient's physical condition and rehabilitation ability. The process of rehabilitation training is complicated and time-consuming, requiring professional guidance, and patients are easily frustrated and lost due to slow progress. In recent years, spinal cord electrical stimulation technology has been developed. For example, CN102202729A discloses a selective stimulation system and signal parameters for medical conditions. Although it provides an improved stimulation system, device, and method for effectively delivering stimulation energy, it depends on the placement of electrodes during treatment, and the treatment effect is pain relief, and it cannot be used for the recovery of spinal cord function. CN112334184A discloses neural stimulation of mixed nerves. This technical solution allows some subjects to obtain effective treatment at the stimulation level. Although it mentions that one or more proprioceptive or motor fiber types of the posterior root and / or dorsal column can be targeted to treat one or more of spasticity, Parkinson's disease, or other motor control disorders, it does not disclose how neural stimulation is specifically performed to help the patient's muscle group activity.

[0003] Traditional epidural spinal cord stimulation has achieved certain success in neuromodulation and gait reconstruction. However, its hardware equipment still has significant limitations in practical applications. These devices can achieve sequential stimulation of the spinal cord and simulate the activity of muscle groups related to gait, thereby helping patients restore motor function and improve their quality of life. To a certain extent, the patient's motor ability has been improved, and related studies have also shown that spinal cord stimulation can activate key motor nerve pathways, thereby promoting the coordinated contraction of specific muscle groups. However, traditional electrical stimulation methods are heavily dependent on the placement of electrodes. The accuracy of electrode position directly affects the effect and accuracy of stimulation. If the electrode is not placed well, it will be difficult to effectively stimulate a specific spinal cord area or nerve root, which will lead to a significant decrease in the stimulation effect, and may even fail to achieve the expected functional recovery. And because it is stimulating the dorsal column of the spinal cord, it is difficult to selectively stimulate certain specific muscle groups.

[0004] There is cerebrospinal fluid of varying thickness between the electrode and the spinal cord and dorsal nerve. Due to the presence of cerebrospinal fluid, the electrical stimulation signal will attenuate during the transmission process, thereby affecting the intensity and effect of the stimulation. The complexity of this physiological structure increases the reliability and consistency of the stimulation signal. In addition, changes in the patient's body position will also have a significant impact on the effect of electrical stimulation. For example, different body positions such as sitting, standing or lying may cause changes in the position of the electrode relative to the spinal cord or nerve root, thereby affecting the conduction path of the current and the stimulation effect. Therefore, in clinical applications, electrode placement and patient position management are very critical links. For patients who need precise and sequential stimulation of specific nerve roots, traditional epidural spinal cord electrical stimulation technology has defects and challenges that cannot be ignored, which limits its effectiveness and stability in a wider range of applications.

[0005] In addition, on the one hand, there are differences in understanding among those skilled in the art; on the other hand, the applicant studied a large number of documents and patents when making the present invention, but due to space limitations, not all details and contents are listed in detail. However, this does not mean that the present invention does not have the characteristics of these prior arts. On the contrary, the present invention already has all the characteristics of the prior art, and the applicant reserves the right to add relevant prior art to the background technology. Summary of the invention

[0006] After high spinal cord injury, due to the interruption of the connection between the distal spinal cord of the injured segment and the upper center, the brain cannot effectively transmit motor commands to the muscles of the lower limbs, resulting in muscle weakness or complete paralysis. Long-term lack of movement and nerve control will cause the lower limb muscles to gradually atrophy, further weakening muscle strength and coordination. In recent years, most researchers believe that in addition to the function of up and down motor sensory conduction, the spinal cord itself has certain intrinsic functions, which provides a theoretical basis for stimulating the lower spinal cord to promote the recovery of motor function of the muscle groups in its innervated segments after high spinal cord injury. Spinal cord electrical stimulation technology has gradually become one of the effective methods for treating spinal cord injury movement disorders. Although there have been studies trying to use traditional spinal epidural electrical stimulation hardware devices to stimulate the spinal cord, it is heavily dependent on the placement of the electrode, that is, the deviation of the placement will make it difficult for the device to stimulate the target area. Furthermore, there is cerebrospinal fluid of different thicknesses between the stimulation electrodes and the spinal cord and dorsal nerve roots. Therefore, the existing epidural electrical stimulation technology of the spinal cord has defects such as poor reliability, great influence of patient posture, and high power consumption. That is, the existing technology cannot accurately and effectively promote the recovery of lower limb function after high-level spinal cord injury, such as lower limb gait disorder.

[0007] In view of the shortcomings of the prior art, the present invention provides an implantable selective spinal nerve root stimulation system, which comprises:

[0008] A stimulator is used to generate an electrical stimulation signal with a frequency, pulse width and intensity to promote the patient's affected limb to generate movement commands,

[0009] At least one stimulation electrode has a stimulation contact at the distal end. These stimulation electrodes extend toward the head along the course of the cauda equina nerve, pass through the dural sac area in the midline, pass through the skin from the inside to the outside through the spinous process gap, or are directly connected to the stimulator along a subcutaneous tunnel.

[0010] The stimulation contact of the stimulation electrode is elastically fixed to the free dorsal root nerve region in an embracing manner, wherein the resistance from the stimulation contact to the cerebrospinal fluid is greater than the resistance between the stimulation contact and the ectopic membrane of the dorsal root nerve elastically fixed thereto. In the present invention, the impedance is expressed as resistance, which does not ignore the impedance when the stimulation signal is a pulse signal, but takes into account that the pulse frequency of the stimulation signal is not high, and using a linear pure resistance can reduce the difficulty of analysis; therefore, the protection scope of the present invention also includes impedance.

[0011] In this technical solution, the resistance from the stimulation contact to the cerebrospinal fluid is greater, while the resistance between the stimulation contact and the dorsal root nerve epifascicle is smaller, making it easier for the current to pass through a path with less resistance and act directly on the target nerve tissue. Specifically, the higher resistance difference makes it easier for the current to be concentrated in a small area. This setting can improve the quality of signal transmission and improve signal fidelity, and more accurately control nerve activation on the basis of ensuring the positioning accuracy of electrical stimulation; this setting can also reduce the system's ineffective stimulation of surrounding non-target nerve tissues and avoid unnecessary side effects; in addition, this setting reduces the ineffective current passing through the cerebrospinal fluid, thereby improving energy utilization and extending battery life. In terms of biocompatibility and long-term efficacy, the low-resistance contact between the stimulation contact and the dorsal root nerve epifascicle helps to maintain good biocompatibility and mechanical stability. Furthermore, the stable electrode-nerve contact ensures the effect of long-term treatment and reduces the risk of frequent adjustment or replacement of electrodes.

[0012] According to a preferred embodiment, the stimulation electrode is arranged with stimulation contacts in pairs, wherein a certain spacing is maintained between the stimulation contacts arranged in pairs, and the spacing can generate a signal loop between the stimulation contacts in pairs, so that the electrical stimulation signal provided by the stimulator can pass through the first stimulation contact elastically fixed to the first region of the dorsal root nerve to the second stimulation contact elastically fixed to the second region of the dorsal root nerve, and induce a current in the dorsal root nerve in the path from the first region of the dorsal root nerve to the second region of the dorsal root nerve, and the current causes the depolarization of the axons in the nerve fiber in the form of a pulse signal. Preferably, the spacing between the stimulation contacts arranged in pairs changes the resistance by changing the path length of the current propagating between the first stimulation contact and the second stimulation contact. Preferably, the resistance between the stimulation contacts arranged in pairs is less than the resistance from the stimulation contact to the cerebrospinal fluid, and the resistance between the stimulation contacts arranged in pairs is adjustable within a certain range (for example, by changing the contact pressure and the contact position) to optimize the propagation efficiency of the current in the dorsal root nerve. Specifically, the present invention preferably uses flexible conductive material to make the stimulation contacts, and applies external force or voltage to deform the material, thereby changing the distance between the first stimulation contact and the second stimulation contact.

[0013] According to a preferred embodiment, a pair of stimulation contacts are used to provide a pulse stimulation signal to a group of nerve fibers in a perifascicle, wherein the stimulation signal parameters of the stimulator for the pair of stimulation contacts are adjusted according to the electromyographic activity of the corresponding limbs triggered by the pulse stimulation signal provided by the group of nerve fibers. Preferably, the contact resistance between the pair of stimulation contacts and the perifascicle is less than the resistance from the stimulation contacts to the cerebrospinal fluid to ensure that the current is mainly transmitted through the nerve fibers in the perifascicle. Specifically, the pulse stimulation signal provided by the group of nerve fibers is transmitted to the dorsal horn neurons of the spinal cord through the dorsal root nerves, the dorsal horn neurons transmit the signal to the anterior horn neurons through the interneurons, and the electrical activity transmitted by the anterior horn neurons through the ventral roots of the spinal nerves triggers the electromyographic activity of the corresponding limbs. Further, the stimulation signal parameters of the stimulator for the pair of stimulation contacts are feedback-adjusted by recording the electromyographic activity.

[0014] According to a preferred embodiment, the stimulation contact of the stimulation electrode is elastically fixed to the free dorsal root nerve region by a C-shaped elastic arm in an embracing manner with a circumferential force, wherein the stimulation electrode provides a pulse stimulation signal to a group of nerve fibers in the inner membrane of the free dorsal root nerve region through a conductive ring fixed to the stimulation contact and facing the outer membrane of the free dorsal root nerve region, and the conductive ring is elastically wrapped by the C-shaped elastic arm on the radial outer side of the dorsal root nerve to which it is fixed, so that the radial outer side of the conductive ring does not contact or tries not to contact the cerebrospinal fluid in the dorsal root nerve region. Preferably, the contact resistance between the conductive ring and the inner membrane of the dorsal root nerve is less than the resistance from the conductive ring to the cerebrospinal fluid.

[0015] According to a preferred embodiment, the C-shaped elastic arms for elastically fixing the stimulation contacts are arranged in pairs, wherein a first elastic arm, a second elastic arm and an opening and closing window between the first and second elastic arms are respectively provided along the length direction of the dorsal root nerve region where they are located. The two elastic arms are used to elastically fix the stimulation contacts to increase resistance, and the opening and closing window is used to engage the clamps to open or close the two elastic arms.

[0016] The purpose of setting up the C-shaped elastic arm is mainly for two aspects: one is to hold the electrode to prevent it from shifting; the other is to keep the conductive part of the electrode away from the cerebrospinal fluid to reduce the loss or interference of the stimulation signal square wave. In the cauda equina area, multiple electrodes are usually arranged in the cerebrospinal fluid. In order to enable the patient to move freely, these electrodes may be stimulated at the same time, and sometimes the current needs to be increased to achieve the therapeutic effect. This may cause crosstalk problems between electrodes. Since each electrode tightly hugs a section of the dorsal root nerve through the C-shaped elastic arm to form a closed loop, and there are multiple such loops in the cerebrospinal fluid, induced currents may be generated between these loops, which is difficult to predict and control.

[0017] The technical solution of the present invention uses a C-shaped elastic arm to hold the dorsal root nerve as much as possible, ensuring that the conductive ring has a large coverage area while isolating the penetration of external cerebrospinal fluid. This design makes the resistance between the radial outer side of the C-shaped elastic arm and the cerebrospinal fluid greater than the resistance between the radial inner side of the C-shaped elastic arm and the dorsal root nerve epifascicle, and then most of the stimulation signals will be efficiently transmitted to the dorsal root nerve through the stimulation contacts, reducing signal loss and interference, and improving the accuracy and effectiveness of stimulation.

[0018] According to a preferred embodiment, the stimulator is configured to deliver an electrical stimulation signal to a selected stimulation electrode among the plurality of stimulation electrodes when the stimulator is connected to the plurality of stimulation electrodes, and the stimulator delivers at least one stimulation pattern to the selected stimulation electrode.

[0019] The stimulator adjusts the frequency, pulse width and intensity of the electrical stimulation signal according to the spatial position of the selected stimulation electrode on the cauda equina nerve and the application time.

[0020] Preferably, the stimulator also adjusts the frequency, pulse width and intensity of the electrical stimulation signal according to the resistance between the selected stimulation electrode and the cauda equina nerve to ensure that the current is mainly transmitted through the nerve fibers in the cauda equina nerve to reduce the impact on non-target tissues.

[0021] Preferably, the stimulator further comprises a time sequence control module, which is capable of controlling the stimulation mode of the selected stimulation electrode in stages according to a preset time sequence.

[0022] According to a preferred embodiment, the waveform of the electrical stimulation signal applied by the stimulator includes a unilateral rectangular waveform, a unilateral pulse waveform, a unilateral triangular waveform, a unilateral sinusoidal waveform, a unilateral random waveform, a unilateral band modulated waveform, a unilateral pulse train waveform, a unilateral linear rise and fall waveform or a combination thereof. Preferably, the stimulator changes the waveform of the electrical stimulation signal by adjusting the resistance between the stimulating electrode and the cauda equina (for example, by changing the contact pressure, contact position and contact area), thereby reducing the impact of the sudden change of the current on the tissue.

[0023] According to a preferred embodiment, the current from the stimulation electrode flows from the conductive ring of the separated dorsal root nerve area into the epifascicle of the dorsal root nerve. The stimulation of the current causes a change in the potential difference between the inside and outside of the epifascicle, causing the epifascicle to depolarize. The current propagates into the dorsal root nerve to the peripheral membrane of the nerve fiber, causing the peripheral membrane to depolarize. The current continues to flow to the internal fascicle that wraps the nerve fiber, causing the action potential to be conducted along the axon.

[0024] According to a preferred embodiment, the paired stimulation contacts are arranged on the dorsal root nerves floating in the cerebrospinal fluid of the subarachnoid space.

[0025] According to a preferred embodiment, the stimulation contacts are designed to be connected to the electrode array of the stimulator in a unilateral or bilateral arrangement according to the nerves to be stimulated.

[0026] Preferably, the electrode array can stimulate the left and right sides or one side of the fourth lumbar nerve, the left and right sides or one side of the fifth lumbar nerve, the left and right sides or one side of the first sacral nerve, and the left and right sides or one side of the second sacral nerve. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of the direction of nerve conduction;

[0028] Figure 2 This is a schematic diagram of the cauda equina anatomy and electrode placement;

[0029] Figure 3 This is a schematic diagram of the transverse anatomy of the spine and the location of the electrodes;

[0030] Figure 4 Schematic diagram of nerve anatomy and the elastic fixation of the stimulation contacts in an embracing manner on the freed dorsal root nerve region;

[0031] Figure 5 Schematic diagram of the C-shaped elastic arm fixed to the freed dorsal root nerve area;

[0032] Figure 6 is a schematic structural diagram of a stimulator and a stimulating electrode according to a preferred embodiment;

[0033] Figure 7is a schematic structural diagram of a stimulator and a stimulating electrode according to another preferred embodiment;

[0034] Figure 8 It is a schematic diagram of the structure of the stimulation contact;

[0035] Fig. 9 A schematic diagram of the opening and closing window of the stimulation contact;

[0036] Fig.10 A schematic diagram of a clamp used to open or close two elastic arms;

[0037] Fig.11 A schematic diagram of a waveform generated by a stimulator in one embodiment;

[0038] Fig.12 A schematic diagram of a waveform generated by a stimulator in another embodiment;

[0039] Fig.13 A schematic diagram of waveforms generated by a stimulator in yet another embodiment.

[0040] Reference numerals list

[0041] 100: stimulator; 110: housing; 120: lead interface; 130: locking member; 200: stimulation electrode; 210: stimulation contact; 211: first stimulation contact; 212: second stimulation contact; 220: lead; 221: insulating layer; 230: conductive ring; 300: dorsal root nerve; 310: first region; 320: second region; 330: posterior horn neuron; 340: anterior horn neuron Element; 350: efferent nerve; 360: effector; 400: C-shaped elastic arm; 410: first elastic arm; 420: second elastic arm; 430: opening and closing window; 431: inner edge of the cut surface; 432: outer edge of the cut surface; 433: flange inside the window; 440: connecting beam; 450: opening and closing mouth; 460: opening flange; 470: flange along the mouth; 500: clamp; 600: spinal cord; 700: cauda equina. DETAILED DESCRIPTION

[0042] The following is a detailed description with reference to the accompanying drawings.

[0043] In the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inside", "outside", etc. is based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In the present invention, unless otherwise clearly specified and limited, the terms "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal connection of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. It should be noted that the drawings disclosed in the following embodiments are all for the convenience of explaining the technical features of the present invention, rather than for limiting its practicable forms.

[0044] The nerve fibers in the dorsal root are sensory nerve fibers, which transmit external sensory information (such as touch, temperature, pain, etc.) to the central nervous system. In the cauda equina 700, the electrical stimulation signal is transmitted along the dorsal root fibers and enters the posterior horn of the spinal cord 600. The cauda equina 700 is composed of multiple spinal nerve roots, including lumbar nerves (L1-L5) and sacral nerves (S1-S5). Each nerve root is differentiated into a posterior root and an anterior root, the posterior root is responsible for sensory information, and the anterior root is responsible for motor signals.

[0045] In the present invention, midline refers to the midline of the body, and the spine extends along the midline. Example

[0046] The present embodiment provides an implantable selective spinal nerve root stimulation system, which includes a stimulator 100 and at least one stimulating electrode 200. The stimulator 100 of the implantable selective spinal nerve root stimulation system is an electronic device for generating an electrical stimulation signal. The stimulator 100 can adjust the frequency, pulse width and intensity of the electrical stimulation signal to promote the affected limb of the patient to generate a movement command. The stimulator 100 is preferably an electronic device having components such as a processor, a memory, and an output interface. The integrated design of the stimulator 100 combines the functions of stimulation signal generation and signal processing. The processor integrated in the stimulator 100 is responsible for generating, regulating and managing the electrical stimulation signal. The electrical stimulation signal generated by the stimulator 100 to promote the patient's affected limb to generate movement is realized by a built-in digital-to-analog converter (DAC). The memory is used to store stimulation parameters and preset programs. The output interface is used to connect the stimulation electrode 200. The power supply of the stimulator 100 is preferably a built-in power supply (such as a rechargeable battery) to provide energy for the entire device. The stimulator 100 can be configured with a wireless communication module (such as Bluetooth or Wi-Fi) to facilitate monitoring and control by external devices such as smartphones or computers. The stimulator 100 preferably has built-in filters and regulators to ensure that the electrical signal transmitted from the stimulator 100 to the stimulation electrode 200 is within a preset range, thereby maximizing the stimulation effect.

[0047] The stimulator 100 integrated with the processor is connected to the stimulation electrode 200 via a lead 220, such as Figure 6 and Figure 7 As shown. The stimulator 100 has a housing 110 that protects the internal electronic components from damage. The housing 110 is preferably flat, circular or rectangular. A lead interface 120 is provided on one side of the stimulator 100. The lead interface 120 is used to connect the lead 220 of the stimulation electrode 200. The lead interface 120 is usually constructed as one or more slots. One slot is preferably connected to a lead 220. The lead interface 120 transmits the electric pulse signal generated by the stimulator 100 to the stimulation electrode 200 through the lead 220. The lead 220 is fixed to the stimulator 100 by a locking member 130. The lead 220 is used to transmit the electric signal sent by the stimulator 100 to the stimulation electrode 200, which can adjust the frequency, pulse width and intensity of the electric stimulation signal, so as to achieve the purpose of stimulating the target part. The lead 220 connecting the stimulator 100 and the stimulation electrode 200 is usually made of a conductive material, which has good conductivity, thereby reducing the signal loss during the transmission process.

[0048] Lead wire 220 starts from lead wire interface 120 of stimulator 100, enters spinal region through skin puncture or surgical incision, extends downward along epidural space or subarachnoid space of spinal column, passes through epidural space or subarachnoid space of spinal column, reaches lumbar sacral spinal cord. Lead wire 220 passes through lumbar sacral spinal cord, continues to extend downward, until reaches the area where cauda equina 700 is located. Cauda equina 700 is an extension of lumbar sacral spinal cord, comprising many nerve roots. Lead wire 220 extends toward head end along the direction of cauda equina 700, and finally reaches the position of stimulation electrode 200. Lead wire 220 is wrapped with insulation layer 221 outside, and this insulation layer 221 can also be constituted as insulation coating layer. Electrical signal is realized by the flow of electric current. When stimulator 100 sends electrical signal, electrical signal generates electric current in lead wire 220, and electric current is transmitted to stimulation contact 210 along the length direction of lead wire 220. When the current reaches the stimulation electrode 200 , the current forms an electric field between the stimulation electrode 200 and the target tissue to promote ion flow, thereby inducing the excitement or contraction of nerves or muscles. The stimulation electrode 200 is preferably a conductive electrode having a stimulation contact 210 .

[0049] The stimulation electrode 200 extends toward the head end along the direction of the cauda equina 700. The stimulation electrode 200 with the stimulation contact 210 passes through the dura mater sac area in the midline, passes through the skin from the inside to the outside through the interspinous space, or is connected to the stimulator 100 through the lead 220 through a subcutaneous tunnel. Preferably, a plurality of stimulation electrodes 200 with the stimulation contact 210 are arranged in parallel along the direction of the cauda equina 700 extending toward the head end, such as Figure 2 As shown, it passes through the dura mater sac area in the midline, passes through the skin from the inside to the outside through the interspinous space, or is connected to the stimulator 100 through a lead 220 through a subcutaneous tunnel. Specifically, a plurality of stimulating electrodes 200 with stimulating contacts 210 extend in parallel along the direction of the cauda equina 700 toward the head end, wherein the stimulating electrodes 200 with stimulating contacts 210 are arranged between the dorsal root ganglion and the dorsal root nerve 300. The parallel stimulating electrodes 200 are anchored to the muscle fascia outside the interspinous space. The arrangement of a plurality of stimulating electrodes 200 is as follows: Figure 2 As shown, the stimulation contacts 210 are arranged according to the nerves to be stimulated, and the side and nerve can be selected according to the condition of the disease. The arrangement of the stimulation electrode 200 is, for example, to stimulate both the left and right sides of the fourth lumbar nerve, but only one of the left and right sides of the fourth lumbar nerve can be stimulated according to the condition of the disease. The stimulation electrode 200 can also be arranged to stimulate the left and right sides of the fifth lumbar nerve, the left and right sides of the first sacral nerve, or the left and right sides of the second sacral nerve. The stimulation electrode 200 is arranged so as to stimulate the left and right sides of the fourth lumbar nerve, the left and right sides of the fifth lumbar nerve, the left and right sides of the first sacral nerve, and the left and right sides of the second sacral nerve. The arrangement position of the stimulation electrode 200 is shown in FIG. Figure 2 shown.

[0050] The stimulation electrode 200 for transmitting the electrical stimulation signal has a stimulation contact 210 at its distal end. The proximal end of the stimulation electrode 200 refers to an end connected to the stimulator 100 that generates the electrical stimulation signal through the lead 220. The distal end of the stimulation electrode 200 refers to a position close to the stimulation target (such as the dorsal root nerve 300). The stimulation electrode 200 is preferably equipped with one or more stimulation contacts 210 at its distal end. The stimulation contacts 210 are designed to be connected to the electrode array of the stimulator 100 in a unilateral or bilateral arrangement according to the nerves to be stimulated. The electrode array can stimulate the left and right sides or one side of the fourth lumbar nerve, the left and right sides or one side of the fifth lumbar nerve, the left and right sides or one side of the first sacral nerve, and the left and right sides or one side of the second sacral nerve. According to the patient's stimulation needs, unilaterally arranged stimulation contacts 210 or bilaterally arranged stimulation contacts 210 can be selected. Specifically, the stimulation contacts 210 are arranged in a unilateral manner, which means that the stimulation contacts 210 are arranged at a certain distance along one side of the lead 220, wherein the stimulation contacts 210 arranged in a unilateral manner are mainly used to stimulate one side of the spinal cord 600, and the specific number is determined according to the treatment needs. The stimulation system of this embodiment can include 4 to 16 contacts, for example. Each stimulation contact 210 is connected to the lead interface 120 of the stimulator 100 through the lead 220. The stimulation contacts 210 are arranged in a bilateral manner, which means that the lead 220 is bifurcated into a Y shape, and the stimulation contacts 210 are arranged at a certain distance on the two arms of the Y-shaped lead 220, wherein the stimulation contacts 210 arranged in a bilateral manner can stimulate both sides of the spinal cord 600 at the same time, and usually include 8 to 32 stimulation contacts 210, 4 to 16 stimulation contacts 210 on each side.

[0051] The stimulation contact 210 is elastically fixed to the free dorsal root nerve 300 area in an embracing manner. The resistance from the stimulation contact 210 to the cerebrospinal fluid is greater than the resistance between the stimulation contact 210 and the outer membrane of the dorsal root nerve 300 where it is elastically fixed. The resistance from the stimulation contact 210 to the cerebrospinal fluid in the dorsal root nerve 300 area close to the cerebrospinal fluid in the dura mater sac is greater, which means that the distribution of the current flowing from the stimulation contact 210 to the cerebrospinal fluid will be restricted, reducing the current intensity transmitted through the cerebrospinal fluid and reducing the stimulation of the surrounding non-target nerves. The resistance between the stimulation contact 210 and the outer membrane of the dorsal root nerve 300 where it is elastically fixed is small, and the current can be concentrated in the area passing through the outer membrane of the dorsal nerve, that is, the contact area of ​​the nerve fibers. This resistance difference allows the current to be more effectively distributed to the target nerve area during stimulation, rather than spreading aimlessly. This technical solution ensures that the electrical stimulation signal produces a clear and accurate action potential in the nerve, thereby improving the controllability of the treatment effect.

[0052] The stimulation electrode 200 extends from the lead interface 120 of the stimulator 100 and is connected to the stimulation contact 210 of the dorsal root nerve 300. The electrical stimulation signal generated by the stimulator 100 is first processed by the processor, and the adjusted electrical stimulation signal is transmitted to the stimulation electrode 200 through the lead 220. The electrical stimulation signal from the proximal end of the stimulation electrode 200 is converted into an effective stimulation pulse at its distal end, and then applied to the stimulation target through the stimulation contact 210 at the distal end.

[0053] The stimulation electrodes 200 extending toward the head end along the direction of the cauda equina 700 are preferably provided with stimulation contacts 210 in pairs. The paired stimulation contacts 210 elastically fixed on the free dorsal root nerve 300 in an embracing manner can form a signal loop to ensure that the current flow is continuous and stable, and the stability of the signal loop helps to maintain the continuity and reliability of nerve stimulation. The stable signal loop formed can reduce the attenuation of the current during the conduction process to ensure that the intensity of the stimulation signal will not significantly decrease with the increase of the propagation distance. The current from the stimulation electrode 200 flows from the stimulation contact 210 into the perifascicle of the dorsal root nerve 300. The resistance between the stimulation contact 210 and the perifascicle elastically fixed to the dorsal root nerve 300 is much smaller than the resistance from the stimulation contact 210 to the cerebrospinal fluid, so the current is more likely to enter the nerve fiber through this path. The path between the stimulation contact 210 with a smaller resistance and the epifasciculus has a smaller resistance, so the current can be efficiently transmitted to the nerve fiber. The stimulation of the current causes a change in the potential difference between the inside and outside of the epifasciculus, thereby producing epifasciculus depolarization. The depolarization of the epifasciculus produces an electric field effect in the surrounding area, which enhances the effect of the membrane on the nerve fiber below, thereby pushing the current inward. The current is transmitted to the surrounding membrane of the nerve fiber, and the membrane potential of the surrounding membrane changes in the direction of depolarization, that is, the potential inside the surrounding membrane rises (compared to the resting state). The change in the potential difference between the inside and outside of the membrane caused by the depolarization of the surrounding membrane pushes the current to continue to propagate inward along the nerve fiber. The flow of current in the surrounding membrane affects the inner fasciculus, and the current continues to flow to the inner fasciculus that wraps a single nerve fiber. After the current reaches the inner fasciculus, it activates the voltage-dependent sodium channels on the membrane, causing sodium ions (Na + ) quickly flows into the cell, further causing depolarization. When the potential in the inner bundle membrane reaches the threshold, it triggers the formation of an action potential. The generated action potential propagates forward in the nerve fiber. The propagation of the action potential triggers the opening of sodium channels in the surrounding area through local depolarization, forming a "fluctuating" potential change. When the action potential reaches the nerve ending (presynaptic membrane), the change in potential causes the depolarization of the presynaptic membrane, prompting the opening of voltage-dependent calcium channels, and calcium ions (Ca² +) flows into the presynaptic membrane. The influx of calcium ions triggers the fusion of synaptic vesicles with the membrane, releasing neurotransmitters (such as glutamate, etc.) into the synaptic cleft. The released neurotransmitters bind to the receptors on the postsynaptic membrane, causing depolarization of the postsynaptic membrane. When the depolarization reaches the threshold, the postsynaptic anterior horn motor neuron of the spinal cord can be stimulated to generate a new action potential, continue to transmit signals along the ventral root of the spinal nerve, and act on the target muscle group to produce muscle activity. On the other hand, the stimulation contacts 210 arranged in pairs allow different stimulation modes, such as alternating stimulation, synchronous stimulation, etc.

[0054] The stimulation contacts 210 arranged in pairs on the stimulation electrodes 200 extending toward the head end along the direction of the cauda equina 700 are kept at a certain distance from each other. The distance between the stimulation contacts 210 arranged in pairs is set in a manner that the resistance between the two stimulation contacts 210 is less than the resistance from the stimulation contacts 210 to the cerebrospinal fluid. The stimulation contacts 210 arranged in pairs include a first stimulation contact 211 elastically fixed to the first region 310 of the dorsal root nerve 300 and a second stimulation contact 212 kept at a certain distance from the first stimulation contact 211 along the length direction of the dorsal root nerve 300. This spacing can generate a signal loop between the paired stimulation contacts 210, so that the electrical stimulation signal provided by the stimulator 100 can go to the second stimulation contact 212 elastically fixed to the second region 320 of the dorsal root nerve 300 via the first stimulation contact 211 elastically fixed to the first region 310 of the dorsal root nerve 300, and induce a current in the dorsal root nerve 300 in the path from the first region 310 of the dorsal root nerve 300 to the second region 320 of the dorsal root nerve 300. The current is in the form of a pulse signal that causes the depolarization of the axons in the nerve fiber. The first region 310 refers to a portion of the dorsal root nerve 300, where the first stimulation contact 211 is fixed. The second region 320 refers to another portion of the dorsal root nerve 300 that is spaced a certain distance from the first region 310, where the second stimulation contact 212 is fixed. The second region 320 receives the electrical signal conducted by the first stimulation contact 211 of the first region 310. The stimulator 100 sends an electrical stimulation signal transmitted in the form of a pulse to the first stimulation contact 211 of the first region 310 of the dorsal root nerve 300. After receiving the electrical stimulation signal, the first stimulation contact 211 sends an electric current to the first region 310 of the dorsal root nerve 300 to activate the nerve fiber, thereby causing the axon in the nerve fiber to depolarize. The current generated by depolarization is transmitted along the nerve fiber, and the formed electrical signal propagates along the axon in the nerve fiber and moves to the second region 320. The current reaches the second region 320 of the dorsal root nerve 300, and the second stimulation contact 212 of the second region 320 receives the pulse signal, further activating the nerve fiber in the second region 320. The current passing through the second stimulation contact 212 will continue to be transmitted to the downstream neural structure, transmitting the information to the central nervous system or other target areas, and completing the transmission of the neural signal. The stimulation contacts 210 arranged in pairs to form a signal loop can provide a more stable current distribution. The spacing between the stimulation contacts 210 arranged in pairs can form a more stable signal loop, ensuring that the flow of current in the neural tissue is continuous and effective. When the stimulation contacts 210 are arranged in pairs and maintain an appropriate spacing, the current can simultaneously or alternately activate adjacent nerve fibers, producing a synchronization effect. The synchronization effect helps to speed up the propagation of electrical signals in the nervous system and reduce signal conduction delays. The stimulation contacts 210 arranged in pairs can also reduce the current intensity required to trigger depolarization by forming an interactive electric field.

[0055] A pair of stimulation contacts 210 arranged at a certain distance on the dorsal root nerve 300 are used to provide a pulse stimulation signal to a group of nerve fibers in the innervation membrane of a dorsal root nerve of a spinal nerve. A certain distance is maintained between the stimulation contacts 210 arranged in pairs, for example, 1 mm. The implantable selective spinal nerve root stimulation system of this embodiment triggers the myoelectric activity of the corresponding limb according to the pulse stimulation signal provided by this group of nerve fibers. Specifically, the pulse stimulation signal provided by this group of nerve fibers is transmitted to the spinal cord posterior horn neurons 330 through the dorsal root nerve 300, and the posterior horn neurons 330 transmit the signal to the anterior horn neurons 340 through the intermediate neurons. The anterior horn neurons 340 trigger the myoelectric activity of the corresponding limb through the electrical activity transmitted by the ventral root of the spinal nerve. This setting feedback-adjusts the stimulation signal parameters of the stimulator 100 for the pair of stimulation contacts 210 by recording the myoelectric activity of the corresponding limb triggered. The stimulation signal parameters are, for example, the frequency, pulse width and intensity of the electrical stimulation signal. Specifically, after cutting the dura mater between the epidural space and the subdural space, the dorsal root nerve 300 is exposed by loosening the arachnoid adhesion. A 2-3 mm long dorsal root nerve 300 is "freed" in the area between the dorsal root nerve 300 medullary region and the dorsal root ganglion. The freed dorsal root nerve 300 area is used to fix the stimulation contact 210 of the stimulation electrode 200, such as Figure 3 and Figure 4 As shown. The stimulator 100 applies an electrical stimulation signal to the stimulation electrode 200 fixed between the dorsal root ganglion of the afferent nerve and the dorsal root nerve 300. The stimulated area generates an electric field, which causes depolarization of the dorsal root nerve 300. Depolarization leads to the formation of an action potential, which is conducted along the dorsal root nerve fibers. A group of nerve fibers in a perifasciculus can be applied with a pulse stimulation signal, and the electrical stimulation signal enters the dorsal horn region from the dorsal root, and the electrical signal is transmitted along the axon to the dorsal horn neuron 330 in the dorsal horn region, as shown. Figure 1 As shown, the depolarization is induced by applying a pulse stimulation signal (multiple waveforms), such as applying a +70mV electrical stimulation signal to a single nerve. The applied electrical stimulation signal far exceeds the threshold of the neuron (usually -55mV), causing Na in the nerve fiber to increase. + The channel opened quickly, Na +Entering the nerve cells causes a dramatic change in membrane potential, thereby generating an action potential. The action potential is transmitted along the axons in the nerve fibers (including the sensory nerve fibers in the dorsal root) to the posterior horn neurons 330, and then transmitted to the skeletal muscles through the anterior horn neurons 340 via the efferent nerves 350 and the ventral roots of the spinal nerves, thereby inducing skeletal muscle movement. Compared with direct stimulation of the ventral roots of the spinal nerves, the signal generated by stimulating the dorsal root nerves 300 is a skeletal muscle movement signal that is more in line with the natural movement state of the human body after the signal processing (conversion) of the dorsal horn neurons 330 and the anterior horn neurons 340, thereby simulating the form of autonomous movement of a healthy human body. Specifically, through the stimulation of the dorsal root nerves 300, the signal is processed by the dorsal horn neurons 330 and the anterior horn neurons 340. This path is consistent with the path of the natural movement signal, and the signal is processed at multiple levels in the spinal cord 600 and can better coordinate the movement of different muscle groups. The movement coordination and adaptability of this path are high, thereby reducing unnecessary muscle spasms. On the contrary, if the ventral root of the spinal nerve is directly stimulated, this path directly bypasses the sensory processing and interneurons in the spinal cord 600, directly activates the anterior horn neurons 340 to cause muscle contraction. Since the multi-level processing in the spinal cord 600 is skipped, the signal is directly transmitted to the target muscle, lacking the regulation and integration of the interneurons, and muscle spasms may occur because the signal does not conform to the natural movement state of the human body. The movement coordination and adaptability of this path are low, and therefore lack dynamic adjustment ability, which is prone to muscle spasms or excessive contraction.

[0056] The stimulation contact 210 of the stimulation electrode 200 is elastically fixed to the freed dorsal root nerve 300 region by a C-shaped elastic arm 400 in a circumferentially applied force embracing manner, such as Figure 4 , Figure 5 , Figure 8 and Fig. 9As shown. The C-shaped elastic arm 400 is elastically fixed to the freed dorsal root nerve 300 region in such a way that the resistance between the radial outer side and the cerebrospinal fluid is greater than the resistance between the radial inner side of the C-shaped elastic arm 400 and the outer membrane of the dorsal root nerve 300. This arrangement allows the stimulation signal to be efficiently transmitted to the dorsal root nerve 300 through the stimulation contact 210. The C-shaped elastic arm 400 refers to an elastic mechanical arm with a C-shaped profile, the curved part of which can embrace or surround the target object, and is usually made of a highly elastic material (such as silicone, rubber or other elastic polymers) that can deform without losing its original shape when an external force is applied. The elasticity and fixing force of the C-shaped elastic arm 400 can be adjusted under certain circumstances. Preferably, the radial outer side of the C-shaped elastic arm 400 is provided as an insulating coating layer to increase the resistance between the conductive ring 230 and the cerebrospinal fluid. Preferably, the resistance between the stimulation contact 210 and the outer membrane of the dorsal root nerve 300 elastically fixed thereto is changed by changing the contact area between the conductive ring 230 on the radial inner side of the C-shaped elastic arm 400 and the dorsal root nerve 300. The surface roughness will affect the contact area, and the larger the contact area, the smaller the contact resistance. The contact area between the conductive ring 230 and the dorsal root nerve 300 is increased, such as by using a ring-shaped, mesh-shaped or comb-shaped stimulation contact 210. The roughness of the contact surface between the conductive ring 230 and the dorsal root nerve 300 is preferably designed to be much smaller than the roughness of the surface on the radial outer side of the C-shaped elastic arm 400 that contacts the cerebrospinal fluid, so that the resistance from the stimulation contact 210 to the cerebrospinal fluid is greater than the resistance between the stimulation contact 210 and the outer membrane of the dorsal root nerve 300 elastically fixed thereto. Alternatively, a conductive gel is used to fill the tiny gap between the conductive ring 230 and the dorsal root nerve 300 to increase the contact area and reduce the contact resistance. The conductive ring 230 preferably uses a highly conductive material to significantly reduce the resistance of the stimulation contact 210 itself, so that the resistance between the stimulation contact 210 and the pericyte elastically fixed to the dorsal root nerve 300 is significantly smaller than the resistance from the stimulation contact 210 to the cerebrospinal fluid.

[0057] like Figure 4As shown, the stimulation contact 210 has a certain width h in the length direction Z of the dorsal root nerve 300. The width h is set in a manner that the resistance from the stimulation contact 210 to the cerebrospinal fluid is greater than the resistance between the stimulation contact 210 and the perifascicle elastically fixed to the dorsal root nerve 300. The width h is set in a manner that the contact area between the stimulation contact 210 and the perifascicle is increased and the resistance between the stimulation contact 210 and the perifascicle elastically fixed to the dorsal root nerve 300 is reduced. The range of width h is preferably 1 to 5 mm. According to a specific embodiment, the width h is about 1 mm. The stimulation contact 210 has a size that matches the diameter of the cauda equina 700 in the circumferential direction C of the dorsal root nerve 300, for example, about 1 mm. When the stimulation contact 210 embraces the dorsal root nerve 300, it applies a certain pressure to the dorsal root nerve 300 through its C-shaped spring arm 400 to keep itself on the dorsal root nerve 300. The stimulation contact 210 has an interface for fixing the stimulation electrode 200 in the circumferential direction, which holds the electrode and the stimulation contact 210 together, for example, in an integrated combination or welding manner. Since the resistance from the radial outer side of the C-shaped elastic arm 400 to the cerebrospinal fluid is greater than the resistance between the radial inner side of the C-shaped elastic arm 400 and the perifascicle, most of the stimulation signals will be transmitted to the dorsal root nerve 300 via the stimulation contact 210. Specifically, the contact area between the radial inner side of the C-shaped elastic arm 400 and the perifascicle is large, which reduces the resistance between the radial inner side of the C-shaped elastic arm 400 and the perifascicle. On the other hand, the stimulation contact 210 carried by the stimulation electrode 200 is elastically fixed to the free dorsal root nerve 300 region by the C-shaped elastic arm 400 in an embracing manner in which a force is applied circumferentially, so that the distance between the stimulation contact 210 and the perifascicle where it is elastically fixed to the dorsal root nerve 300 is shorter, thereby reducing the resistance between the stimulation contact 210 and the perifascicle where it is elastically fixed to the dorsal root nerve 300. The stimulation electrode 200 provides a pulse stimulation signal to a group of nerve fibers in the inner perimyelium of the dorsal root nerve 300 region through a conductive ring 230 fixed to the stimulation contact 210 and facing the outer perimyelium of the free dorsal root nerve 300 region. The conductive ring 230 is elastically wrapped by the C-shaped elastic arm 400 on the radial outer side of the dorsal root nerve 300 to which it is fixed, so that the radial outer side of the conductive ring 230 does not contact or tries not to contact the cerebrospinal fluid in the dorsal root nerve 300 region. That is, the conductive ring 230 is in the inner cavity of the C-shaped elastic arm 400 and is close to its inner wall. The conductive ring 230 is close to the outer perimyelium of the dorsal root nerve 300, and the C-shaped elastic arm 400 is wrapped on the radial outer side of the conductive ring 230, which not only forms a protective layer, but also prevents the conductive ring 230 from shifting. The C-shaped elastic arm 400 provides additional protection, reduces the friction between the conductive ring 230 and the surrounding tissue, and thus prolongs the service life of the electrode. The conductive ring 230 and the C-shaped elastic arm 400 are aligned in the axial direction, ensuring that the conductive ring 230 as a whole is effectively protected by the C-shaped elastic arm 400 .In addition, the elastic design of the C-shaped elastic arm 400 enables it to adapt to the slight movement of the dorsal root nerve 300 and maintain the stable position of the conductive ring 230 while reducing the pressure on the nerve.

[0058] The C-shaped elastic arms 400 for elastically fixing the stimulation contacts 210 are arranged in pairs, wherein the first elastic arm 410, the second elastic arm 420 and the opening and closing window 430 between the first and second elastic arms 420 are respectively provided along the length direction of the dorsal root nerve 300 region where the C-shaped elastic arms 400 are located. The two elastic arms are used to elastically fix the stimulation contacts 210 to increase resistance, and the opening and closing window 430 is used to engage the clamp 500 to open or close the two elastic arms. Fig.10 Specifically, the opening and closing window 430 facing the tip of the C-shaped elastic arm 400 has a connecting beam 440 connecting the two elastic arms in the length direction of the dorsal root nerve 300 region. The ends of the first elastic arm 410 and the second elastic arm 420 away from the connecting beam 440 are not closed, forming a freely openable opening 450, which allows the first elastic arm 410 and the second elastic arm 420 to be opened or closed under the action of the clamp 500. The connecting beam 440 can be stretched open under the radial outward force of the jaws of the clamp 500 to surround the dorsal root nerve 300 and the corresponding conductive ring 230 of the stimulation contact 210 arranged thereon, and when the stretching force of the jaws of the clamp 500 is released, the first elastic arm 410 and the second elastic arm 420 can return to embrace the conductive ring 230 under the action of the restoring force of their elastic arms, wherein when the first elastic arm 410 and the second elastic arm 420 rotate back to embrace their respective conductive rings 230, the connecting beam 440 can serve as the vertical rotation axis of the first elastic arm 410 and the second elastic arm 420.

[0059] like Fig. 9 As shown, the present invention particularly designs a C-shaped elastic arm 400 shaped like a cylindrical structure, which is intended to achieve elastic fixation of the stimulation contact 210. The C-shaped elastic arm 400 is composed of a first elastic arm 410 and a second elastic arm 420 arranged relatively to each other, and the two are connected by a connecting beam 440 located in the middle, and the connecting beam 440 ensures that the first elastic arm 410 and the second elastic arm 420 are connected to each other away from one end thereof. The first elastic arm 410 and the second elastic arm 420 are both designed as arc surface structures, and preferably, elastic materials such as silica gel and medical grade polyurethane can be selected for manufacture. When not subjected to external force, the curvature of the two elastic arms is the same, which ensures that they can be evenly attached to the dorsal root nerve 300 with the same elastic fastening force, forming a stable and uniform pressure distribution, and achieving an embracing fixation of the dorsal root nerve 300.

[0060] The ends of the first elastic arm 410 and the second elastic arm 420 away from the connecting beam 440 can be selectively closed or kept open according to the diameter of the dorsal root nerve 300 to which they are sleeved. When sleeved on the outside of a dorsal root nerve 300 with a smaller diameter, the ends of the two elastic arms are in close contact to achieve natural closure; while when sleeved on the outside of a dorsal root nerve 300 with a larger diameter, the two elastic arms are insufficient to achieve complete closure, so that an opening 450 is formed between their two ends.

[0061] At least one approximately annular conductive ring 230 is provided on the inner wall of the C-shaped elastic arm 400, near both ends of the axial direction. In view of the openable and closable characteristics of the first elastic arm 410 and the second elastic arm 420, the conductive ring 230 is designed to be disconnected at the openable and closable ends of the two elastic arms, and at least a certain gap is reserved to accommodate the fine-tuning change of the shapes of the two elastic arms.

[0062] The design of the C-shaped elastic arm 400 in the present invention not only helps to fix the conductive ring 230 and prevent it from displacement, but also effectively isolates the conductive ring 230 from the cerebrospinal fluid in the external environment. The two elastic arms elastically fix the stimulation contact 210 in an embracing manner to increase the resistance from the stimulation contact 210 to the cerebrospinal fluid, thereby reducing the attenuation or interference that may be encountered during the transmission of the stimulation signal. To this end, the axial ends of the C-shaped elastic arm 400 are equipped with flanges 470 to achieve effective isolation between the inside and the outside, especially to isolate the conductive ring 230 from the cerebrospinal fluid. The conductive ring 230 is not directly installed at the axial ends of the C-shaped elastic arm 400, but a distance is left, so that the flanges 470 can fill this gap, further preventing the cerebrospinal fluid from invading the internal space of the C-shaped elastic arm 400 from the axial direction. At the same time, from the axial perspective of the C-shaped elastic arm 400, the edge flange 470 protrudes in the radial direction by a certain thickness, which is greater than or at least equal to the thickness of the conductive ring 230, so as to ensure that the edge flange 470 can effectively protect the conductive ring 230 from the influence of the external environment from the axial direction.

[0063] The first elastic arm 410 and the second elastic arm 420 can form ports of a specific shape at the opening and closing mouth 450, and these ports can be perfectly docked when the opening and closing mouth 450 is closed. This specific shape can be a sawtooth shape, a wavy shape, or other forms with similar structural features. Traditional planar contacts tend to lead to a larger parallel plate capacitor effect, resulting in higher parasitic capacitance. In contrast, special-shaped structures (such as sawtooth or wavy shapes) effectively reduce parasitic capacitance by reducing the alignment of parallel surfaces between the two conductors. In addition, the design of the special-shaped structure also plays an important role in reducing parasitic inductance. It makes the path through which the current flows more tortuous and increases the length of the current path. At the same time, this tortuous path design also helps to destroy the closed loop of the magnetic field that may be formed, reduce the mutual inductance effect, thereby further reducing the parasitic inductance and maximizing the effect of electrical stimulation.

[0064] The first elastic arm 410 and the second elastic arm 420 are equipped with an opening flange 460 extending along the axial direction of the C-shaped elastic arm 400 at the inner side of the end close to the opening 450. In order to prevent cerebrospinal fluid from penetrating into the cylindrical space inside the C-shaped elastic arm 400 through the opening 450, the opening flange 460 is specially designed to fill the gap between the conductive ring 230 and the two elastic arms' special-shaped openable and closable ports, and extends along the axial direction of the C-shaped elastic arm 400 to match the special-shaped ports. The opening flange 460 protrudes radially outward by a certain thickness, ensuring that the thickness is greater than or at least equal to the thickness of the conductive ring 230, thereby effectively protecting the conductive ring 230 from the circumferential direction and preventing it from being affected by external environmental factors. This arrangement allows the C-shaped elastic arm 400 to be elastically fixed to the freed dorsal root nerve 300 region in an embracing manner with circumferential force applied, and the resistance between the stimulation contact 210 and the epifascicle of the dorsal root nerve 300 to which it is elastically fixed is much smaller than the resistance from the stimulation contact 210 to the cerebrospinal fluid.

[0065] The connecting beam 440 works together with the first elastic arm 410 and the second elastic arm 420 to achieve complete or partial wrapping of the dorsal root nerve 300 area. The connecting beam 440 forms an opening and closing window 430 on its circumferential side wall by local excision to connect the internal and external spaces of the C-shaped elastic arm 400. Preferably, the shape and area of ​​the opening and closing window 430 are defined by four sections around it, wherein the left and right side sections serve as the boundary marks between the connecting beam 440 and the first elastic arm 410 or the second elastic arm 420 respectively; and the spacing between the upper and lower sections in the axial direction of the C-shaped elastic arm 400 is set to an upper limit to ensure that the conductive ring 230 is not exposed to the outside. The opening and closing window 430 is preferably designed as a regular rectangle, which is convenient for the insertion of the end of the clamp 500, and the equal opening or closing of the first elastic arm 410 and the second elastic arm 420 is achieved through the operation of the clamp 500. Because of its regular edge design, it can better adapt to the surface curvature of the dorsal root nerve 300 and effectively reduce the risk of external cerebrospinal fluid penetration.

[0066] Each section of the opening and closing window 430 includes two boundaries: one is the inner edge 431 of the section that is close to the surface of the dorsal root nerve 300, and the other is the outer edge 432 of the section located on the peripheral surface of the C-shaped elastic arm 400. In order to further improve the sealing performance of the edge of the opening and closing window 430, the area enclosed by the four inner edges 431 of the four sections is designed to be larger than the area of ​​the four outer edges 432 of the sections. This means that in the upper section of the opening and closing window 430, the height of the inner edge 431 of the section located on the radial inner side of the C-shaped elastic arm 400 is higher than the height of the outer edge 432 of the section located on the radial outer side; and in the lower section of the opening and closing window 430, the height of the inner edge 431 of the section located on the radial inner side is lower than the height of the outer edge 432 of the section located on the radial outer side. In addition, the angle formed between the left or right section of the opening and closing window 430 and the peripheral surface of the C-shaped elastic arm 400 is preferably an acute angle. When observing the opening and closing window 430 from a radial perspective, its four sections present a closing structure that gradually narrows from the inside to the outside. On the contrary, when observing from the (possible) infiltration direction of cerebrospinal fluid, the cross-section of the opening and closing window 430 on the circumference of the C-shaped elastic arm 400 is the smallest, and as the cerebrospinal fluid gradually infiltrates inward, its cross-section will gradually increase. According to the Bernoulli principle, when the cerebrospinal fluid flows in the contraction area, its flow rate will increase, and the increase in flow rate will be accompanied by a decrease in pressure. In the closed structure of the opening and closing window 430, the cerebrospinal fluid will first pass through the narrowest part (i.e., the minimum cross-section of the opening and closing window 430 formed by the four outer edges 432 of the cut surface), and then enter the larger spatial area (i.e., the area between the minimum cross-section and the maximum cross-section formed by the four inner edges 431 of the cut surface). This design allows the cerebrospinal fluid to be rapidly accelerated when flowing through the minimum cross-section of the opening and closing window 430, thereby causing the pressure entering the spatial area to be rapidly reduced, making it more difficult for external cerebrospinal fluid to penetrate into the interior through the opening and closing window 430, thereby enhancing the anti-penetration ability, and ultimately making the resistance from the stimulation contact 210 to the cerebrospinal fluid greater than the resistance between the stimulation contact 210 and the epifascicle elastically fixed to the dorsal root nerve 300.

[0067] Preferably, the four inner edges 431 of the opening and closing window 430 are all provided with inner window flanges 433 to further enhance the ability to prevent cerebrospinal fluid from penetrating. Specifically, the inner window flanges 433 of the left and right cut surfaces of the opening and closing window 430 can extend to a certain width along the circumferential direction of the inner wall surface of the connecting beam 440; the inner window flanges 433 of the upper and lower cut surfaces of the opening and closing window 430 extend to a certain width along the axial direction of the inner wall surface of the connecting beam 440.

[0068] The stimulator 100 is configured to deliver an electrical stimulation signal to a selected stimulation electrode 200 among the plurality of stimulation electrodes 200 when it is connected to the plurality of stimulation electrodes 200, and the stimulator 100 delivers at least one stimulation mode to the selected stimulation electrode 200, wherein the stimulator 100 adjusts the frequency, pulse width and intensity of the electrical stimulation signal according to the spatial position of the selected stimulation electrode 200 on the cauda equina nerve 700 and the application time. Preferably, the stimulator 100 further includes a time sequence control module, which can control the stimulation mode of the selected stimulation electrode 200 in stages according to a preset time sequence. Preferably, the stimulation mode delivered by the stimulator 100 to the selected stimulation electrode 200 includes one or more of a single pulse mode, a continuous pulse mode, an alternating pulse mode and a modulated pulse mode. For example, during surgery, the C-shaped elastic arm 400 is opened by the clamp 500 through the opening and closing window 430, and the conductive ring 230 is fixed on the epifascicle of the dorsal root nerve 300. This embodiment takes the selection of a specific position on the cauda equina 700 (L4-L5 and S1-S2 segments) for electrical stimulation as an example. For the L4-L5 segment, the continuous pulse mode is selected with a frequency of 20 Hz, a pulse width of 200 μs, and an initial intensity of 0.5 mA. For the S1-S2 segment, the modulated pulse mode is selected, the frequency gradually increases from 20 Hz to 30 Hz, the pulse width is 200 μs, and the initial intensity is 0.5 mA. The intensity is gradually adjusted according to the patient's tolerance and treatment effect. For example, the initial intensity can be set to 0.5 mA, and gradually increased to 1.0 mA according to the patient's feedback.

[0069] The waveform of the electrical stimulation signal applied by the stimulator 100 includes a unilateral rectangular waveform, a unilateral pulse waveform, a unilateral triangle waveform, a unilateral sine waveform, a unilateral random waveform, a unilateral band modulated waveform, a unilateral pulse train waveform, a unilateral linear rise and fall waveform or a combination thereof. The waveform examples provided in this embodiment are as follows Figure 11~Figure 13 shown.

[0070] The current from the stimulation electrode 200 flows from the conductive ring 230 of the separated dorsal root nerve 300 area into the epifascicle of the dorsal root nerve 300. The stimulation of the current causes a change in the potential difference between the inside and outside of the epifascicle, causing the epifascicle to depolarize. The current propagates into the dorsal root nerve 300 to the peripheral membrane of the nerve fiber, causing the peripheral membrane to depolarize. The current continues to flow to the internal membrane that wraps the nerve fiber, causing the action potential to be conducted along the axon.

[0071] The paired stimulation contacts 210 are arranged on the dorsal root nerve 300 floating in the cerebrospinal fluid of the subarachnoid space. The paired stimulation contacts 210 provide an independent current channel with low or negligible resistance between the stimulation contacts 210 and the perifascicle of the dorsal root nerve 300, thereby reducing the possibility of current passing through the cerebrospinal fluid. Preferably, the stimulator 100 can adjust the number, arrangement form and application order of the electrical stimulation signals of the stimulation electrodes 200 according to the patient's condition. For example, for the L4-L5 segment of the patient, one stimulation electrode 200 is used, and four stimulation contacts 210 are arranged unilaterally along the perifascicle of the dorsal root nerve 300; for the S1-S2 segment, one stimulation electrode 200 is used, and four stimulation contacts 210 are arranged bilaterally along the perifascicle of the dorsal root nerve 300. The application order of the electrical stimulation signals is as follows:

[0072] Initial stage: L4-L5 segment: first activated, using continuous pulse mode, frequency of 20 Hz, pulse width of 200 μs, initial intensity of 0.5 mA. S1-S2 segment: subsequently activated, using modulated pulse mode, frequency gradually increased from 20 Hz to 30 Hz, pulse width of 200 μs, initial intensity of 0.5 mA.

[0073] Mid-term adjustment: L4-L5 segment: 20 Hz and 0.5 mA can be maintained; if the patient's gait recovery is limited, the frequency can be increased to 30 Hz and the intensity can be increased to 1.0 mA. S1-S2 segment: adjust the frequency range to 20 Hz to 40 Hz and increase the intensity to 1.0 mA.

[0074] Post-optimization: Further optimize the stimulation mode and parameters based on patient feedback and treatment effects.

[0075] It should be noted that the above-mentioned specific embodiments are exemplary, and those skilled in the art can come up with various solutions inspired by the disclosure of the present invention, and these solutions also belong to the disclosure scope of the present invention and fall within the protection scope of the present invention. Those skilled in the art should understand that the present invention specification and its drawings are illustrative and do not constitute a limitation of the claims. The scope of protection of the present invention is defined by the claims and their equivalents. The present invention specification contains multiple inventive concepts, such as "preferably" and "according to a preferred embodiment", both of which indicate that the corresponding paragraph discloses an independent concept, and the applicant reserves the right to file a divisional application based on each inventive concept. Throughout the text, the features guided by "preferably" are only an optional method and should not be understood as being required. Therefore, the applicant reserves the right to abandon or delete the relevant preferred features at any time.

Claims

1. An implantable selective spinal nerve root stimulation system, comprising: A stimulator (100) is used to generate an electrical stimulation signal having a frequency, pulse width and intensity to promote the patient's affected limb to generate movement commands, At least one stimulation electrode (200) has a stimulation contact (210) at the distal end. The stimulation electrodes (200) extend toward the head end along the direction of the cauda equina nerve (700), pass through the dural sac area in the midline, pass through the skin from the inside to the outside through the interspinous space, or are directly connected to the stimulator (100) along a subcutaneous tunnel. It is characterized in that The stimulation contact (210) of the stimulation electrode (200) is elastically fixed in an embracing manner to the freed dorsal root nerve (300) region, wherein the resistance between the stimulation contact (210) and the cerebrospinal fluid is greater than the resistance between the stimulation contact (210) and the perifascicle of the dorsal root nerve (300) to which it is elastically fixed. The stimulation electrodes (200) are arranged with stimulation contacts (210) in pairs, wherein a certain distance is maintained between the stimulation contacts (210) arranged in pairs, and the distance can generate a signal loop between the stimulation contacts (210) in pairs, so that the electrical stimulation signal provided by the stimulator (100) can pass from the first stimulation contact (211) elastically fixed to the first area (310) of the dorsal root nerve (300) to the second stimulation contact (212) elastically fixed to the second area (320) of the dorsal root nerve (300), thereby inducing an electric current in the dorsal root nerve (300) in the path from the first area (310) of the dorsal root nerve (300) to the second area (320) of the dorsal root nerve (300). The stimulation contact (210) of the stimulation electrode (200) is elastically fixed to the freed dorsal root nerve (300) region in an embracing manner by means of a C-shaped elastic arm (400) that applies a circumferential force.

2. The implantable selective spinal nerve root stimulation system according to claim 1, characterized in that: This current is in the form of a pulse signal that causes depolarization of the axons in the nerve fibers.

3. The implantable selective spinal nerve root stimulation system according to claim 1 or 2, characterized in that: A pair of stimulation contacts (210) is used to provide a pulse stimulation signal to a group of nerve fibers in a perifasciculus, wherein the stimulation signal parameters of the stimulator (100) for the pair of stimulation contacts (210) are adjusted according to the myoelectric activity of the corresponding limb caused by the pulse stimulation signal provided by the group of nerve fibers.

4. The implantable selective spinal nerve root stimulation system according to claim 1, characterized in that: The stimulation electrode (200) provides a pulse stimulation signal to a group of nerve fibers in the inner perimyelium of the dorsal root nerve (300) through a conductive ring (230) fixed to the stimulation contact (210) and facing the outer perimyelium of the freed dorsal root nerve (300). The conductive ring (230) is elastically wrapped by the C-shaped elastic arm (400) on the radial outer side of the dorsal root nerve (300) to which it is fixed, so that the radial outer side of the conductive ring (230) does not contact or tries not to contact the cerebrospinal fluid in the dorsal root nerve (300) area.

5. The implantable selective spinal nerve root stimulation system according to claim 4, characterized in that: The C-shaped elastic arms (400) for elastically fixing the stimulation contact (210) are arranged in pairs, wherein along the length direction of the dorsal root nerve (300) region where the C-shaped elastic arms (400) are located, there are respectively provided with a first elastic arm (410), a second elastic arm (420), and an opening and closing window (430) between the first elastic arm (410) and the second elastic arm (420), wherein the two elastic arms are used to elastically fix the stimulation contact (210) to increase resistance, and the opening and closing window (430) is used to engage the clamp (500) to open or close the two elastic arms.

6. The implantable selective spinal nerve root stimulation system according to claim 1, characterized in that: The stimulator (100) is configured to deliver an electrical stimulation signal to a selected stimulation electrode (200) among the plurality of stimulation electrodes (200) when it is connected to the plurality of stimulation electrodes (200), and the stimulator (100) delivers at least one stimulation pattern to the selected stimulation electrode (200). The stimulator (100) adjusts the frequency, pulse width and intensity of the electrical stimulation signal according to the spatial position of the selected stimulation electrode (200) on the cauda equina nerve (700) and the application time.

7. The implantable selective spinal nerve root stimulation system according to claim 1, characterized in that: The waveform of the electrical stimulation signal applied by the stimulator (100) includes a unilateral rectangular waveform, a unilateral pulse waveform, a unilateral triangle waveform, a unilateral sine waveform, a unilateral random waveform, a unilateral band modulation waveform, a unilateral pulse train waveform, a unilateral linear rise and fall waveform or a combination thereof.

8. The implantable selective spinal nerve root stimulation system according to claim 1, characterized in that: The current from the stimulation electrode (200) flows from the conductive ring (230) of the separated dorsal root nerve (300) area into the epifascicle of the dorsal root nerve (300). The stimulation of the current causes a change in the potential difference between the inside and outside of the epifascicle, causing the epifascicle to depolarize. The current propagates into the dorsal root nerve (300) to the peripheral membrane of the nerve fiber, causing the peripheral membrane to depolarize. The current continues to flow to the internal membrane that wraps the nerve fiber, causing the action potential to be transmitted along the axon.

9. The implantable selective spinal nerve root stimulation system according to claim 2, characterized in that: Pairs of stimulation contacts (210) are placed on the dorsal root nerves (300) floating in the cerebrospinal fluid between the subarachnoid space.

10. The implantable selective spinal nerve root stimulation system according to claim 1, characterized in that: The stimulation contacts (210) are designed to be connected to the electrode array of the stimulator (100) in a unilateral or bilateral arrangement according to the nerves to be stimulated.

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