Systems and methods for inducing muscle contraction

Abstract

The present invention relates to a method, device, and system for inducing flexion in a target muscle. The device for actuating a target muscle of a patient includes an electromyograph (EMG), a multi-channel cuff electrode (MCE), and a pulse generator having both external and implantable components. The EMG receives weak input from the target muscle in response to flexion, and the MCE can be implanted on or in a motor nerve that innervates the target muscle. The pulse generator drives an electric current between two or more channels of the MCE to induce flexion of the target muscle.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Application No. 63 / 228,754 (Attorney Docket No. 61435-703.101), filed August 3, 2021, the entire contents of which are incorporated herein by reference.

[0002] 1. FIELD OF THEINVENTION The present invention relates generally to medical devices and methods, and more particularly to methods, apparatus and systems for inducing flexion in target muscles. [Background technology]

[0003] (background) Damage to movement-controlling areas of the brain and spinal cord (the central nervous system, "CNS") results in weakness and paralysis. Signals sent from an injured CNS are too impaired to communicate with the working peripheral nervous system (PNS). Without this working connection, the PNS cannot initiate movement. Stroke is one of the most common CNS injuries, leaving approximately 40 million post-stroke patients worldwide with residual limb defects. The number is growing by 8.3 to 9.4 million per year. Functional improvement of these defects is currently based on long-term rehabilitation, which lasts approximately several months to several years. However, progress plateaus at 6 months. A total of 50% of all stroke survivors with limb defects will be unable to meaningfully use their arms for activities of daily living. Other CNS injury conditions also leave residual limb defects, including spinal cord injury (27.3% of all US paralysis), multiple sclerosis, MS (18.6%), and cerebral palsy CP (8.3%). Post-stroke recovery is a largely unentered market, and there are currently no approved invasive technological aids for limb restoration.

[0004] To date, there have been few, if any, devices that could adequately treat such patients. A group in France has recently selectively stimulated muscle groups in the upper extremity using a multi-cuff electrode (MCE) wrapped around the radial and median nerves in the forearm during intraoperative testing. See Tigra et al., cited below. The Tigra disclosure (1) focuses distally (i.e., the forearm) without a clear target for proximal movement, (2) is neither a functional nor an implantable clinical device, (3) uses a single cuff system and therefore cannot selectively activate nerve fiber bundles, (4) is limited to four contacts per ring electrode, (5) is not a closed-loop device, 6) lacks longitudinal data, and (7) targets spinal cord injury patients with quadriplegia without clear translation to the stroke population.

[0005] Polasek et al. (2009) IEEE Trans Neural Syst Rehabil Eng 17(5): 428-437 describe the use of multi-channel spiral cuff electrodes to stimulate human nerves and elicit muscle contractions. Electrodes were accessed percutaneously or fully implanted. An open-loop system was used to detect voluntary movement and subsequently stimulate the nerve to restore limb function.

[0006] For these reasons, it would be desirable to provide improved devices, systems, and methods for inducing flexion or other movements in target muscles. In particular, it would be beneficial to provide devices, systems, and methods that minimize or eliminate the need for transepidermal access to the implantable components of the system for recharging, reprogramming, upgrading, and other communication and power management tasks that occur after initial implantation.

[0007] (2. List of Background Art) Related techniques include Polasek et al. (2009) IEEE Trans Neural Syst Rehabil Eng 17(5): 428-437; Tigra et al. (2020) J Neuroeng Rehabil 17:66, WO2002 / 087683, WO2019 / 046547, US11331493, US9272139, US10751532, US2010 / 031230, US19293151, US2004 / 0024439, US8942824, US9114246, US7324853, US4750499, US2019 / 0183472, and US9895546. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. 2002 / 087683 [Non-patent literature]

[0009] [Non-Patent Document 1] Polasek et al. (2009) IEEE Trans Neural System Rehabil Eng 17(5): 428-437 Summary of the Invention [Means for solving the problem]

[0010] SUMMARY OF THEINVENTION The present invention comprises a closed-loop device that bypasses the damaged CNS and restores function to a weakened limb by directly stimulating functional nerves in the PNS. The CNS sends a weakened signal to the PNS in an attempt to initiate arm flexion. An implanted or external electromyography (EMG) electrode detects this signal and directly stimulates a pulse generator that is connected to a multi-cuff electrode (MCE) or other electrode assembly that is surgically implanted around one or more intact nerves (i.e., musculocutaneous nerves) or other nerves in the arm. Each electrode assembly stimulates a unique subpopulation of nerve fiber bundles, selectively activating, for example, a discrete muscle in the limb (i.e., the biceps brachii). The arm flexes in response. In a specific implementation, the device of the present invention (1) provides eight or more channels per ring electrode for specialized current steering and stimulation selectivity, (2) utilizes closed-loop circuitry to facilitate ease of use for the end user, and (3) allows for the implantation of multiple cuffs around multiple nerves, thereby providing partial or complete resuscitation of the entire arm and restoration of arm function.

[0011] Although EMG electrodes are described, it should be understood that the systems and methods of the present invention are operable with any electrodes or other sensors capable of detecting muscle movement or signals that may induce such muscle movement, including electroencephalography (EEG), electroneurography (ENG), and the like. In addition, the pulse generator may be controlled by an external or internal driver that is programmed to initiate muscle movement, for example, in response to programmed patterns for rehabilitation or in response to patient or other user input; for example, the patient may have an interface that allows the patient to initiate muscle movement on command.

[0012] The device according to the invention may target post-stroke recovery as part of the stroke management market for patients suffering from arm weakness or paralysis. In the United States, there are approximately 7 million post-stroke patients. A total of 50-88% will have chronic upper limb impairments even after active rehabilitation, leading to a current market share of 3.5-6 million patients who could benefit from our device. The annual incidence of stroke in the United States is 610,000 new cases / year, leading to an additional market share of 305,000-536,000 new patients per year who could benefit from our device. In Europe, there are approximately 9 million surviving post-stroke patients. The annual incidence of stroke in Europe is 825,000 new cases / year, leading to an additional market share of 412,000-726,000 new patients per year who could benefit from our device.

[0013] In particular, the devices and systems of the present invention will be useful for treating patients recovering from spinal cord injury, traumatic brain injury, traumatic nerve injury, among other pathologies affecting the CNS, as well as acute or chronic stroke patients who have difficulty flexing their arms at the elbow but are otherwise able to open and close their hands. For example, in the United States, there are approximately 294,000 survivors with SCI, with an estimated 17,800 new cases per year. In Europe, there are approximately 500,000 survivors with SCI, with an estimated 8,900 new cases per year.

[0014] An illustrative device according to the principles of the present invention utilizes electromyography (EMG) input to trigger an internal pulse generator (IPG) to stimulate a multi-channel cuff electrode (MCE) around a peripheral nerve to restore motion. For example, in restoring elbow flexion in a stroke patient with residual weakness, an EMG lead would be implanted or placed near a weak arm flexor (e.g., biceps brachii or coracobrachialis), whose weak motion would trigger a multi-channel cuff electrode around the musculocutaneous nerve to restore full elbow flexion strength.

[0015] In specific cases, the invention provides a closed loop device to restore motor function in frailty or paralysis, typically comprising 1) an input (e.g., EMG-wired / wireless, EEG-wired / wireless, ENG-wired / wireless, or other input); 2) a pulse generator that receives the input; and 3) an output in the form of one or more cuffs or other electrodes with one or more channels that are wrapped around one or more nerves.

[0016] The device according to the present invention typically comprises one or more electrodes that can interface with a nerve. The device may further comprise a receiver-stimulator, a ground electrode, and other components, and typically has the capacity to receive EMG, ENG, or EEG information, either wirelessly or wired. The device of the present invention is useful for treating or reducing paralysis or weakness, and the method of using the device includes (a) implanting the device in the paralyzed limb, where multiple electrodes are wrapped around a nerve (e.g., musculocutaneous nerve), (b) placing a surface or intramuscular electronic device in the muscle, i.e., EEG data serves as an input upon detection of muscle contraction or EEG activity, or receiving ENG input from additional electrodes or stimulation leads with input and output capabilities, and (c) providing programmed and graded stimulation to the appropriate electrodes, thereby generating symmetric contraction of the corresponding muscle on the paralyzed side.

[0017] In some embodiments, the devices of the present invention help achieve active and voluntary locomotion in patients suffering from limb weakness or paralysis.

[0018] In some embodiments, a method of treating paralysis and / or weakness in a subject includes (a) detecting EMG activity, EEG activity, or ENG (electroneurography) activity in a muscle, and (b) treating the paralysis by direct targeted stimulation of corresponding muscles or nerve fibers on the weak or paralyzed limb.

[0019] In some embodiments, a method of treating paralysis and / or weakness or injury in a subject comprises (a) detecting the level of contraction of individual muscles or EEG or ENG signals, and (b) treating the paralysis by direct targeted stimulation of corresponding nerve fibers in the paralyzed limb.

[0020] In an embodiment, the closed loop device restores motor function in patients with weakness or paralysis. An external pulse generator (EPG) collects weak muscle activity using electromyography (EMG) signals, either wired or wirelessly. It converts the EMG signals to digital signals, processes the digital signals, encodes them into radio frequency (RF) signals, and transmits them to a receiver-stimulator coil (RSC). The hermetically sealed stimulator contains active electronics that derive power from the RF signals, decodes the signals, converts them into electrical currents, and transmits them along multi-channel cuff electrodes (MCEs) wrapped around the nerves. Electrodes at the ends of the wires stimulate the peripheral nerves, restoring movement in patients with weakness or paralysis.

[0021] In other embodiments, the system may have a single cuff electrode with input and output capabilities that can detect weak nerve pulses and then stimulate the nerve to induce muscle contraction or flexion. Such a cuff electrode would be configured to have both sensing and stimulation capabilities.

[0022] In a first specific aspect of the invention, a device for actuating a target muscle of a patient comprises an electrode assembly and a pulse generator, including an external component and an implantable component. The electrode assembly is typically configured to be implanted on or in a motor nerve that innervates the target muscle, and the pulse generator may typically be configured to drive current between two or more channels of the assembly to the electrode assembly to induce flexion of the target muscle. However, in some cases, the electrode assembly may comprise, consist essentially of, or consist of a single ring or other electrode configured to stimulate the target nerve and induce muscle flexion or other movement.

[0023] The external component of the pulse generator typically includes (1) circuitry configured to receive EMG-generated flexion signals and deliver stimulation signals transepidermally to the implantable component, and (2) a power source configured to inductively deliver power to the implantable component. The internal component of the pulse generator typically includes (1) circuitry configured to receive stimulation signals from the external component and deliver stimulation current to the electrodes, and (2) a power source configured to inductively receive power to the external component.

[0024] The device may further optionally include a sensor or driver for triggering generation of a stimulation current by the pulse generator. Most commonly, the device will include a sensor that detects an initial target muscle flexion or movement, typically an EMG sensor, typically a patch electrode, mounted externally over the target muscle and configured to detect an attempted flexion of the target muscle and generate a flexion signal in response thereto. Other suitable sensors include electroencephalography (EEG), electroneurography (ENG), and the like, which can detect activity in the patient's brain or the patient's peripheral or central nerves that are indicative of an attempted or initial muscle flexion or movement.

[0025] In still other cases, the device may further comprise a driver that is typically programmed to stimulate the target muscles in a preselected pattern for therapy. The preselected pattern can be repetitive, for example for therapy, or can be provided to allow the patient to initiate muscle movement on demand, for example, using a manual, verbal, or other input signal.

[0026] In an exemplary embodiment, the electrode assembly comprises a cuff electrode configured to be wrapped around a motor nerve, for example comprising a multi-channel cuff electrode (MCE). The MCE will typically comprise a sleeve or other substrate having a two-dimensional array of electrode elements formed over its inner surface that are configured to contact the outer surface of the nerve when the sleeve is wrapped around or otherwise implanted over the nerve. The electrode array may comprise 2-50 individual electrode elements, usually 2-20 individual electrode elements, typically 8-12 individual electrode elements. The individual electrode elements are typically sized to fit within a range of 0.001 mm. 2 ~0.1mm 2 , typically 0.005mm 2 ~0.05mm 2 In most cases, it is within the range of about 0.1 mm. 2 The sleeve will have an exposed contact area (ie, the area that contacts the outer nerve surface when the sleeve is wrapped around the nerve) of approximately 0.1 mm x 0.1 mm.

[0027] The individual electrode elements in such an electrode array will usually be arranged in a linear pattern (disposed along axial and circumferential lines when the sleeve is wrapped around or otherwise implanted over the nerve), but may also be arranged in spiral, irregular, or other patterns. The individual electrode elements will typically be connectable to the pulse generator by individual wires in the lead, although multiplexed and / or wireless connections may be provided in some cases.

[0028] In other embodiments, the electrode assembly may comprise one, two or more circumferential ring electrodes having an axial width in the range of 0.1 mm to 0.5 mm and an inner diameter (when centered on the nerve) in the range of 0.2 cm to 2 cm, usually 0.1 cm to 1 cm, and in most cases about 0.4 cm to 0.6 cm.

[0029] In the illustrated embodiment, the MCE comprises at least four circumferentially distributed active electrode elements arranged in a circular pattern when the cuff is wrapped around the nerve, typically comprising at least two axially separated annular structures of the four or more electrode elements. Additionally or alternatively, the MCE may further comprise one or more active ring electrode elements and / or at least one ground electrode element.

[0030] In further instances, the circuitry of the external pulse generator component may include an amplifier for receiving an input signal from a sensor or driver, e.g., a flexion signal from an EMG signal, signal processing circuitry for generating a stimulation signal, and a transmitter for transepidermally delivering the stimulation signal to the implantable component. Often, the power supply of the external pulse generator component includes a rechargeable battery and an induction coil for delivering power to the implantable component.

[0031] In a second specific aspect of the invention, a method for inducing flexion or other movement in a target muscle of a patient includes generating a motor or drive signal, e.g., externally generating a flexion signal in response to an electromyography (EMG) signal characteristic of an attempted flexion of the target muscle, and receiving the flexion signal within an external component of a pulse generator. A stimulation signal generated by the external component in response to the flexion signal is wirelessly transmitted to a subcutaneously implanted internal component of the pulse generator, and a stimulation current produced by the internal component of the pulse generator is delivered to a motor nerve innervating the target muscle to induce flexion of the muscle.

[0032] Alternatively, the method may further include stimulating the target muscles in a preselected pattern, typically for therapy. The preselected pattern may be repetitive, for example for therapy, or may be provided on demand to allow the patient to initiate muscle movement, for example, using a manual, verbal, or other input signal.

[0033] The target muscle often comprises the patient's biceps muscle and the target nerve comprises the musculocutaneous nerve, which controls the biceps muscle, although the methods and devices herein can also be used in conjunction with a variety of other target muscles and target nerves that innervate and control the target muscle, including those innervated by cranial nerves such as the trapezius nerve.

[0034] In an exemplary embodiment of the methods herein, the flexion signal is produced by a patch electrode positioned over the target muscle, which may be wired or wirelessly connected to an external component of the pulse generator.

[0035] In specific embodiments, the stimulation signal may be at least partially digital, while in other embodiments, the stimulation signal may be at least partially analog.

[0036] In the illustrated embodiment, the stimulation current is delivered to the motor nerve by a cuff electrode that is wrapped around the motor nerve, although other electrode interfaces may also be used. The cuff electrode would typically be connected by wires subcutaneously to an implanted component of the pulse generator.

[0037] The methods herein typically further include inductively recharging a battery in the implantable component of the pulse generator using a power source in the external component, and in some cases may further include magnetically anchoring the external component of the pulse generator over the implanted component of the pulse generator. [Brief description of the drawings]

[0038] [Figure 1] FIG. 1 illustrates a first system constructed in accordance with the principles of the present invention.

[0039] [Diagram 2] FIG. 2 illustrates a second system constructed in accordance with the principles of the present invention.

[0040] [Diagram 3] Figure 3 provides an image of a prototype MCE (Panel A), an 8-channel MCE including two parallel electrode rings with four rectangular platinum electrodes, each arranged 90 degrees apart within a silicone enclosure, an intraoperative image of two MCEs implanted into the superior and inferior branches of the facial nerve FN in a cat (Panel B), and an image of the male Omnetics connector resulting from the MCE (Panel C).

[0041] [Figure 4] Figure 4 shows (left) an image of an 8-channel MCE with a two-electrode "ring" with four rectangular (1.5 x 0.25 x 0.038 mm) platinum electrodes, each spaced 90° apart within a silicon enclosure. The current source is controlled by an 8-channel digital-to-analog converter (TDT RX8), which delivers biphasic electrical 82 μs pulses. (Right) is an intraoperative image of the implanted MCE.

[0042] [Diagram 5] FIG. 5 illustrates an apparatus according to the present invention including an electrode assembly and a pulse generator comprising external and implantable components.

[0043] [Figure 6] FIG. 6 is an exploded view of the electrode assembly of FIG. 5 showing the arrangement of the individual electrode elements.

[0044] [Figure 7] FIG. 7 is a block diagram showing circuitry within the external and implantable components of the pulse generator of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] Detailed Description of the Invention With reference to FIG. 1, the system of the present invention includes an implantable pulse generator (IPG) 10 and an implantable sensing lead 12. The IPG contains electronics and a battery inside a titanium case. A surgeon implants the IPG subcutaneously below the clavicle in the upper chest or in the axilla, and connects the IPG to the sensing lead and stimulation is connected to a multi-channel cuff electrode (MCE) 14. An algorithm detects weak electromyography (EMG) signals when arm flexion is attempted and delivers stimulation current to one or more channels of the MCE 14, which are wrapped around the musculocutaneous nerve MN, which innervates the patient's biceps BM. The IPG will typically be MRI compatible and have the ability to be wirelessly charged via a transepidermal magnetic charging coil. The multi-channel cuff electrode (MCE) 14 has a cuff with a 2-mm to 6-mm diameter and a 1-cm to 2-cm length. The cuff electrode contacts are arranged in two or more "rings", the sectional rings containing four individual 2-mm x 1-mm rectangular (tripolar) platinum or 90 / 10 platinum / iridium contacts embedded in silicone positioned at 0, 90, 180, and 270 degrees around the ring. 1-mm to 5-mm spacing is maintained between the contacts, with a 1-mm space from the contacts to the cuff edge. This arrangement allows for monopolar stimulation of discrete nerve locations as well as bipolar stimulation between the two contacts. These dimensions are meant to be exemplary and not limiting in any way.

[0046] The cuff may have sutures embedded in the silicone to facilitate cuff placement. The surgeon positions the MCE around the patient's musculocutaneous nerve and connects the connector distal end of the lead to the IPG. The cuff electrode applies an electrical current that stimulates the musculocutaneous nerve as the arm is flexed at the elbow. A sensing lead may be placed in the biceps brachii and contains an electromyography (EMG) sensor to detect a weak EMG signal during attempted arm flexion.

[0047] The IPG is configured to wirelessly interface with an external handheld device that may be placed epicutaneously over the implant and provide a non-invasive means for the patient to activate the IPG, adjust stimulation parameters (within physician-prescribed limits), check battery status, and, optionally, wirelessly recharge.

[0048] The IPG is further configured to wirelessly interface with a physician programmer, which may include a tablet computer and a telemetry cable having a telemetry head. The telemetry head communicates with the IPG through the skin via short-range radio frequency (RF) telemetry. The telemetry communication allows a physician to non-invasively query and configure the IPG settings. The physician programmer has the capability to monitor EMG waveforms, configure stimulation modes, adjust stimulation parameter values, and store waveforms and settings.

[0049] The system typically further includes EMG sticker electrodes that are placed on the skin over any functional muscle in the body to provide a non-invasive means for the patient or physician to use EMG input from any muscle in the body to be delivered to the IPG via short-range RF telemetry. The EMG sticker electrodes provide an alternative source of input to the implanted EMG sensing leads.

[0050] With reference to FIG. 2, an alternative system of the present invention includes an implantable receiver-stimulator coil (RSC) 20 connected by a stimulation lead to an implantable multi-channel cuff electrode (MCE) 24. The RSC is typically MR compatible. The surgeon implants the RSC 22 subcutaneously in the upper chest below the clavicle or in the armpit and connects to the stimulation lead. The MCE 24 comprises a cuff, typically having a 2-mm to 6-mm diameter and a 1-cm to 2-cm length. The cuff electrode contacts are arranged in two or more "rings", the section rings containing four individual 2-mm x 1-mm rectangular (tripolar) platinum or 90 / 10 platinum / iridium contacts embedded in silicone positioned at 0, 90, 180, and 270 degrees around the ring. The contacts are spaced 1-mm to 5-mm apart, with a 1-mm space from the contacts to the cuff edge. This arrangement allows for monopolar stimulation of discrete nerve locations as well as bipolar stimulation between the two contacts. The cuff can optionally have embedded sutures in the silicone to facilitate cuff placement. The surgeon typically positions the MCE around the patient's musculocutaneous nerve and connects the connector distal end of the lead to the RSC. The cuff electrodes are configured to apply an electrical current that stimulates the musculocutaneous nerve and flexes the arm at the elbow.

[0051] In contrast to the first embodiment, an alternative system employs an external pulse generator (EPG) and an external coil to power the implanted RSC. The EPG and coil are typically located within a housing 26, which is positioned over the RSC 20, as shown by the arrow 28 in FIG. 2, allowing the external and internal coils to be aligned. The EPG contains electronics and a battery inside a titanium case, includes or is connected to an external EMG sensor, and further includes a processor or controller, which is programmed with an algorithm that detects weak electromyographic signals from the EMG electrodes when arm flexion is attempted. The algorithm is further programmed for the EPG to deliver stimulation to one or more channels of the MCE, which are wrapped around the musculocutaneous nerve. The EMG input from the sticker electrodes is sent to the EPG, which will typically be magnetically attached externally and interfaced through the skin with the implanted RSC.

[0052] An alternative system would typically further include a mobile remote apparatus, typically a handheld device, configured to be placed epicutaneously over the implant and to provide a non-invasive means for the patient to activate the RSC, adjust stimulation parameters (within physician-prescribed limits), and check battery status.

[0053] Alternative systems would also include a physician programmer, similar to that of the first embodiment, typically comprising a tablet computer that communicates with the IPG through the skin, for example, via short-range radio frequency (RF) telemetry, and a telemetry cable / head that allows a physician to non-invasively query and configure the IPG settings. The physician programmer has the capability to monitor EMG waveforms, configure stimulation modes, adjust stimulation parameter values, and store waveforms and settings.

[0054] External EMG sticker electrodes can be placed on the skin over any functional muscle in the body, providing a non-invasive means for the patient or physician to use EMG input from any muscle in the body to be delivered to the RSC. The EMG electrodes can communicate with the EPG in a wired or wireless manner.

[0055] With reference to Figures 3 and 4, four custom 8-channel multichannel cuff electrodes (MCEs) designed according to the principles of the present invention have been fabricated by MicroProbes for Life Science (Gaithersburg, MD, USA). Each cuff has an inner diameter of 1.5 mm with two separate rings of four 100 pm rectangular platinum contacts arranged concentrically every 90 degrees (0°, 90°, 180°, 270°) within a silicon enclosure. The arrangement of rings and contacts allows for monopolar stimulation of unique spatial locations on the nerve. A second parallel ring allows for field steering in which two electrodes of the same cuff can be stimulated simultaneously to elicit an amplified response. Charge injection capacity is -164 pC / cm at 1 inA with a phase duration of 82 pS (0.5-1.5 KC / phase). 2 The electrode impedance was 0.5 kfl at 1,000 Hz.

[0056] The device in Figure 4 has operating stimulation parameters that are monophasic or biphasic, with currents typically in the range of 0.1-20 mA, with repetitions in the range of 1-50 pulses / sec and durations in the range of 10-200 μs. The device is designed and built to be physician programmable and patient adaptable through machine learning capabilities, for example to mimic normal use of arm flexion.

[0057] The electrode structure can distribute current across any number of electrode elements or other contacts, allowing independent and / or synchronous activation of any number of electrodes. Each electrode element or contact can be configured as an anode or a cathode during the active phase of stimulation. Stimulation parameters can be programmed, such as intensity (range 0.1 mA-2.5 mA), pulse width (range 10 μs-500 μs), and frequency (range 10 Hz-50 kHz).

[0058] Stimulation waveforms will typically be biphasic, asymmetric, and charge-balanced, with a 100 μs delay between the active and recovery phases. Current strengths range from 40 μA to 2,000 μA.

[0059] The device of the present invention may include one or more cuff electrodes, which can be configured to stimulate one or more nerves and / or multiple locations on a single nerve. Each cuff electrode can contain one or more contacts that are used to stimulate a nerve. The electrode configuration can be as simple as a single ring electrode or can be more complex, with multiple rings.

[0060] 5, a system 30 for activating a target muscle in accordance with the principles of the present invention will be described. System 30 comprises an EMG sensor 32, an electrode assembly 34, and a pulse generator 36. Pulse generator 36 includes an implantable component 38 and an external component 40, the external component connected to electrode assembly 34 by lead 48, and implantable component 40 connected to EMG sensor 32 by lead 60. Implantable component 38 includes circuitry 52 and an inductive coil 54 located within implantable housing 39, and external component 40 includes circuitry 62 and an inductive coil 64 located within external housing 41. The implantable housing 39 is adapted or configured to be implanted subcutaneously in any of the locations described above, such as below the clavicle in the upper chest or in the axilla, and the external housing 41 is adapted or configured to be secured to the patient's skin in a location proximate to the location of the implanted housing 39, preferably directly over the implanted housing, to improve communication between the external and implanted components of the pulse generator 36. Optimally, a magnetic coupling element (shown diagrammatically by dashed line 46 in FIG. 7 ) may be provided to help position and immobilize the external housing 41 over the implanted housing 39.

[0061] As best seen in FIG. 6, the electrode assembly 34 preferably comprises a cuff 42, typically a multi-electrode cuff, having a plurality of electrode elements 44 formed over its inner surface. The electrode elements 44 are formed on the inner surface of a substrate or other support matrix for the cuff 42, which may be folded or wrapped over the target nerve to engage some or all of the electrode elements against the outer surface of the nerve. The electrode elements may comprise different sizes and orientations, for example, two, three, four, or more channel electrodes 44a may be distributed circumferentially over the inner surface of the substrate such that they circumscribe the nerve when the substrate is wrapped or folded over the nerve. Additionally or alternatively, a ring electrode 44b may be formed to circumscribe the inner surface of the cuff in a continuous manner, and a ground electrode 44c may be provided when bipolar operation is desired. Alternatively, of course, any two of the channel electrodes 44 or one or more channel electrodes and ring electrodes and / or ground may be connected and operated in a bipolar mode.

[0062] 7, further description of the circuitry 52 and 62 in the implantable component 38 and the external component 40, respectively, will be provided. The circuitry 52 in the implantable component 38 typically includes a transmitter / receiver XMTR / REC configured for transepidermal transmission and reception of low power data (digital and / or analog) between the implantable component 38 and the external component 40. The transmitter / receiver receives power from a power supply PS, which also provides power to the signal processing unit SP and the stimulator unit STIM. The power supply PS typically includes a battery or capacitor, which can be recharged via an induction coil 54, which receives charge from an induction coil 64 in the external component 40. The signal processing unit SP will be programmed to receive instructions from the external component 40 and control and / or adjust parameters of the stimulator STIM according to those instructions. The stimulator STIM in turn generates and selectively delivers electrical current to individual wires or channels 50 of the lead 48, which is connected to the cuff 34, to activate the target muscles.

[0063] Circuitry 62 within the external component 40 typically includes a transmitter / receiver XMTR / REC configured for transepidermal transmission and reception of low-power data (digital and / or analog) with the implantable component 38. The transmitter / receiver receives power from a power supply PS, which also provides power to a signal processing unit SP and an amplifier AMP. The power supply PS is in turn powered by a rechargeable battery, which may be recharged in a wired or wireless manner, as is common for handheld digital devices. Although not shown, the external component 40 will typically have a display and I / O capabilities to allow for programming and updating of the internal logic. The amplifier AMP is configured to be externally connected to the EMG electrodes 12 by leads 60, although wireless communication may also be used.

[0064] Although certain embodiments or examples of the present disclosure have been described in detail, variations and modifications will be apparent to those skilled in the art, including embodiments or examples that may not provide all of the features and benefits described herein. It will be understood by those skilled in the art that the present disclosure extends beyond the specifically disclosed embodiments or examples to other alternative or additional examples or embodiments and / or applications and obvious modifications and their equivalents. In addition, while some variations have been shown and described in various details, other modifications that fall within the scope of the present disclosure will be readily apparent to those skilled in the art based on the present disclosure. It is also contemplated that various combinations or subcombinations of the specific features and aspects of the embodiments and examples may be made and still fall within the scope of the present disclosure. Thus, it should be understood that various features and aspects of the disclosed embodiments may be combined with or substituted for one another to form various aspects or examples of the present disclosure. Thus, it is intended that the scope of the present disclosure disclosed herein should not be limited by the specific disclosed embodiments or examples described above. With respect to all of the embodiments and examples described above, the steps of any method need not be performed, for example, sequentially.

Claims

1. 1. A device for activating a target muscle in a patient, comprising: an electrode assembly configured to be implanted on or in a motor nerve that innervates the target muscle; a pulse generator comprising an external component and an implantable component, the pulse generator configured to deliver an electrical current to the electrode assembly to induce movement of the target muscle; Equipped with the external component comprises: (1) circuitry configured to receive a drive signal generated by a sensor or a driver and to transepidermally deliver a stimulation signal to the implantable component; and (2) a power source configured to inductively deliver power to the implantable component; The device, wherein the internal component comprises: (1) circuitry configured to receive the stimulation signal from the external component and deliver a stimulation current to the electrodes; and (2) a power supply configured to inductively receive power to the external component.

2. The apparatus of claim 1 , further comprising a sensor or driver configured to generate the drive signal.

3. 10. The device of claim 1, further comprising an electromyography (EMG) sensor mounted externally over the target muscle and configured to detect an attempted flexion of the target muscle and, in response, generate a flexion signal.

4. The device of claim 3 , wherein the EMG sensor comprises a patch electrode.

5. The device of any one of claims 1 to 4, wherein the electrode assembly comprises a cuff electrode configured to be wrapped around the motor nerve.

6. The device of claim 5 , wherein the cuff electrode comprises a multi-channel cuff electrode (MCE).

7. The apparatus of claim 6 , wherein the stimulation signal comprises a current driven between two or more channels of the MCE.

8. The device of claim 6 , wherein the MCE comprises at least four circumferentially distributed active electrode elements.

9. The device of claim 8 , wherein the MCE further comprises at least one active ring electrode element.

10. The apparatus of claim 8 , wherein the MCE further comprises at least one ground electrode element.

11. 5. The device of claim 1, wherein the circuitry of the external component of the pulse generator comprises an amplifier for receiving the flexion signal from the EMG signal, signal processing circuitry for generating the stimulation signal, and a transmitter for transepidermally delivering the stimulation signal to the implantable component.

12. 12. The device of claim 11, wherein the power supply for the external component of the pulse generator comprises a rechargeable battery and an induction coil for delivering power to the implantable component.

Images