WO2020002801A1

WO2020002801A1 - Method and system for neuromuscular stimulation

Info

Publication number: WO2020002801A1
Application number: PCT/FR2019/051522
Authority: WO
Inventors: André GILLE; Pascal BLONDELLE; Hubert Forgeot
Original assignee: Ga. Promotion
Priority date: 2018-06-29
Filing date: 2019-06-21
Publication date: 2020-01-02
Also published as: FR3083123A1; MA53016A; EP3813924A1

Abstract

The invention relates to a stimulation method in which sequences of electrical pulses are applied by means of skin electrodes. Triggering of a sequence of pulses is controlled by detection of a physiological signal of a subject via biofeedback, wherein the frequency of the pulses is between 0.5 Hz and 200 Hz.

Description

NEURO-MUSCULAR STIMULATION METHOD AND SYSTEM

Field of the invention

The present invention relates to the field of neuro-muscular stimulation consisting in causing the triggering, by electrical, magnetic or haptic pulses, of the muscular contraction of a muscle affected by paresis by central lesion or by damage to the peripheral nerve.

The denervated muscle loses its activity, which has consequences on its structure and its trophicity with atrophy of the muscle fibers. These modifications start from the first week following denervation and are predominant during the first month.

The stimulation of a denervated muscle differs from that of a healthy muscle in that the activation of muscle fibers requires specific stimuli.

In the presence of a traumatic lesion of the peripheral nerves, the measurement of chronaxies makes it possible to establish whether the denervation is weak, partial or total.

The purpose of excito-motor treatment is to maintain trophism and limit muscular sclerosis to allow the muscle to be as functional as possible at the end of the re-innervation process which can sometimes last several months.

The effectiveness of this type of treatment depends very much on the correct configuration of the stimulation parameters; these must be defined specifically for each patient and must change over time.

The pulses are generated by a device and transmitted by electrodes placed on the skin in the immediate vicinity of the muscles to be stimulated or by haptic or magnetic excitations. The pulses mimic the action potential from the central nervous system, causing a muscle sensory biofeedback, including muscle contraction.

Neuro-muscular electrical stimulation is generally used as a therapeutic intervention for muscle building. It can be used to increase the strength of an injured or healthy muscle. It is generally used on the superficial muscles of the arms, shoulder girdle, perineal or abdominal, legs and lower back. An isolated lesion with specific reductions in muscle strength, such as weakness of the quadriceps or lumbar artery or pelvic muscles is the most common degradation treated by neuromuscular electrical stimulation (NMS) to allow contraction of paralyzed muscles. a lesion of the central nervous system, of medullary origin which can cause paraplegia, or of cerebral origin (stroke) which can cause hemiplegia or even originate from other neuromotor disorders. It is also used in the field of sport for training the muscles and recovering them after exercise.

Neurostimulation is sometimes associated with electromyography (EMG) consisting of recording the electrical potentials emitted by a muscle during its voluntary contraction. The surface EMG gives access to the superficial muscles. During a weak contraction, we observe some potentials of motor units beating at low frequency. During a stronger contraction, we observe a phenomenon of temporal and spatial recruitment. The magnitude of the EMG is proportional to the force of contraction delivered by the muscle.

Devices using EMG to control electrical stimulation of a given muscle, require placing on said muscle either five different and specific electrodes, including two electrodes for electrical stimulation and three electrodes for EMG, or a combination of at least three electrodes, including two active electrodes for stimulation and for EMG measurement and a reference electrode grounded and grounded.

The electrodes used in this type of device must provide a uniform electrical distribution on the skin of a person under the entire surface of the electrode, in other words a constant current density per unit area of the electrode to ensure coupling. correct. Due to the natural curves inherent in the human body, it is obvious that the electrodes must not only be flexible to adhere perfectly to the contours of the skin under the electrode, but also to accommodate the relative movements of the person's skin.

Stimulation can also be achieved by mechanical vibrations applied to the patient's skin in the vicinity of the muscle to be rehabilitated, or by magnetic excitations.

State of the art

The European patent application EP3315168 which describes a neurostimulation system in the context of the restoration of locomotion in patients suffering from a spinal cord injury (SCI) is known in the prior art and consists in electrically stimulating the spinal cord during a voluntary and / or assisted walk. This patent proposes to administer epidural stimulation of the electrical spinal cord based on brain activity controlled by a neurosensor, such as a network of electrodes. In this way, the application of electrical stimulation can be controlled in a closed loop in response to changes in brain activity. The method described in this patent aims, in a first mode, to monitor the activity of the motor cortex while not stimulating any nerve fibers and, in a second mode, by stimulating the nerve fiber (s) and monitor the activity of the motor cortex during and after stimulation of the nerve fiber (s). This solution relates to a context totally different from the invention, namely the use of cortex activity signals to control non-denervated muscles, in cases of spinal cord injury, while the invention on the contrary relates to the reeducation of a muscle, in particular denervated from a patient whose nervous system presents no disorder. This prior art document therefore has no relevance with regard to the invention which is the subject of this patent.

Patent application US20180036531 relates to a system for controlling stimulation pulses. Stimulation pulses are known in the art, in particular electrical muscle stimulation (EMS) or vibration to stimulate various biological tissues such as muscles and nerves. The goal is to allow athletes to learn, train or improve optimal movement sequences. This prior art solution relates to a device for controlling stimulation pulses during stimulation on a user, comprising a sensor, at least one data processing unit and at least one pulse unit, in which

a) the sensor is suitable for measuring one or more measured values,

b) the data processing unit is configured to generate a control signal to the pulse unit as a function of the measured value or values of the sensor or sensors c) the pulse unit is capable of triggering stimulation pulses and is configured to vary one or more stimulation pulse parameters according to the control signal, in particular when the control signal is generated, a comparison between the measured value (s) and the threshold is performed.

This document does not relate to the rehabilitation of a muscle, in particular denervated, but the learning of sequences of movements by stimulation cycles aimed at creating reflexes for a user without muscular disorders.

Patent application US20180001086 describes flexible sheets that can be used in systems, methods and devices for neuromuscular stimulation, detection and recording. Generally, such systems are used to receive thought signals indicating an intentional action and to provide electrical stimulation to the nerves and / or muscles in order to perform the intended action, thereby bypassing or assisting a damaged or degenerate region / pathway of the system. nervous. The flexible sheets of the present description can be used to make neuromuscular stimulation cuffs, also called here "neural sleeves", which deliver stimulation to restore movement in parts of the body not under voluntary control due to neural regions / pathways. damaged or degenerated, brain or spinal cord injury, stroke, nerve damage, neuromotor disease and other conditions The system can also be used in a patient with local degeneration of neurons or muscles for therapeutic or rehabilitative purposes.

This document does not provide a solution to the field of rehabilitation by stimulation of a muscle, in particular denervated.

Patent application W02016196784 describes a process for the rehabilitation of a patient with a motor impairment, comprising the steps consisting in:

receive electrical signals from electrodes placed on or in the patient's head;

- determine an intention to move a specific part of the patient's body from electrical signals; determine a level of focus of the patient from the electrical signals and based on the intention to move and focus at the level, delivering electrical stimulation through the sleeve electrodes of a sleeve positioned on the specific part of the patient's body to cause movement of the specific part of the body.

The intention to move is captured by different sensors and the stimulation is not specific to a given muscle but to a set of muscles concerned by the intention to move.

Solution provided by the invention

In order to remedy this drawback, the invention relates, according to its most general meaning, to a method of muscular stimulation consisting in applying via skin electrodes pulse sequences characterized in that the triggering of a sequence of pulses is controlled by the detection of a physiological signal of muscular biological feedback from a subject, the frequency of the pulses being between 0.5 Hz and 200 Hz.

By “physiological signal of muscular biological feedback” is meant or shortened by “signal

physiological ”a bioelectric or mechanical signal produced by the activation of a measured muscle, voluntarily by the decision of a subject actively participating in exercise and / or involuntarily (for example, after activation

artificial muscle measured by electrical or haptic stimulation). An electroencephalographic (EEG) or electro-spinal signal is not assimilated to a physiological biological muscle feedback signal within the meaning of this patent because it does not make it possible to discern a particular muscle to be rehabilitated and does not make it possible to detect activation. of a denervated muscle.

The stimulations are either of the electrical type and applied by electrodes formed by elements conducting electric current, or of the mechanical type, under the form of transcutaneous vibration stimulation from 30 to 100 hours applied by electrodes constituted in this case by transducers, for example piezoelectric transducers. The term electrode covers, within the meaning of this patent, the two types of applicators, namely an electrical conductor or an electromechanical vibratory transducer.

According to independent or combined variants:

- Said physiological signal is detected by a second series of skin electrodes different from a first series of electrodes for the application of said pulse sequences.

- Said physiological signal is detected by the series of skin electrodes used for the application of said pulse sequence, the method comprising a step for extracting from the measurement signal the information correlated to said pulse sequence.

- the triggering and the maintenance of a pulse sequence is controlled by the detection of a muscular activity in response to an action of the patient, in the absence of stimulation, by skin electrodes detecting an electromyographic surface signal, the frequency of the pulses being between 0.5 Hz and 200 Hz.

- the process controls the recording of muscle activity simultaneously with the passage of stimulation.

said detection of muscle activity corresponds to the contraction of a first muscle group and in that said pulse sequence is applied to a second muscle group.

said detection of a muscle activity corresponds to the contraction of a first muscle group and in that said sequence of pulses and recording of muscle activity is applied to a second muscle group. it includes a step of triggering a sequence of pulses controlled by the detection of involuntary muscle activity in the absence of stimulation and in the absence of patient action, by skin electrodes detecting an electromyographic surface signal , the pulse frequency being less than 10 Hz.

the energy of the pulses is a function of the characteristics of the electromyographic signals detected.

the electrical pulses are regulated in voltage and in current as a function of the characteristics of the electromyographic signals detected.

it comprises the acquisition of an electromyographic signal and a processing to cancel in the electrocardiogram signal the component corresponding to said electromyographic signal.

- It also includes the generation of a sound signal as a function of the detected electromyographic signal.

- It also includes the control of a light source at the time of stimulation.

The invention also relates to a muscle stimulation system for implementing the method according to the above invention, characterized in that it comprises at least one stimulation electrode and two detection electrodes and a computer controlling the generation of a pulse stimulation sequence with a frequency between 0.5 Hz and 200 Hz, after the detection of muscle activity in the absence of stimulation.

According to independent or combined variants:

- The system also includes a multidirectional inertial sensor secured to a skin electrode. - It has a plurality of outputs delivering the same EMG signal, for the connection of a plurality of electrodes to simultaneously re-educate several muscle groups.

- It includes radio frequency communication means for the transmission of stimulation information and of detection of physiological signals to remote equipment.

- It includes means for transcutaneous vibration stimulation from 30 to 100 Hz.

Detailed description of a nonlimiting example of

The invention

The present invention will be better understood on reading the detailed description of a nonlimiting example of the invention which follows, referring to the accompanying drawings in which:

- Figure 1 shows a schematic view of a system for implementing the invention

- Figure 2 shows a view of the block diagram of a generator for equipment according to the invention.

General framework of the invention

The invention relates generally to a method and a system for muscle or nerve stimulation by the application, via skin electrodes, of sequences of electrical pulses.

The goal of muscle electrostimulation (ESM) is to create or amplify muscle contractions by external stimulation, in particular to rehabilitate control failures by the central and peripheral nervous system of a patient. Muscle electrostimulation sends external electrical impulses which act on the across the skin. In both cases, the muscle reacts and contracts. The invention also applies to electrostimulation of the vagus nerve.

The main advantages of using electrostimulation are:

• During electrostimulation, all muscle fibers work simultaneously, which makes it a very effective form of training and rehabilitation

• the muscle or nervous group to be treated can be determined selectively by the application of skin electrodes.

The invention relates more particularly to the use of electrostimulation for rehabilitation, for the recovery of full control of muscle control.

For this, the triggering of electrostimulation must be correlated with a voluntary initiative of the patient.

In the prior art, it has been proposed to take such a voluntary initiative into account indirectly by encouraging the patient to blow a whistle. This action induces the activation of certain muscles to be re-educated, and also results in the synchronous emission of a sound which serves as a trigger for the stimulation sequence.

The invention consists in detecting not such a sound indirectly correlated to the will of the patient, but a physiological signal by one or more skin bioelectric sensors. These signals include:

• Electromyogram (EMG) signals that measure muscle tension

• Mechanical signals caused by the contraction of a muscle (for example sphincter or pelvic muscles), detected by a balloon producing an electrical signal depending on the pressure exerted by the muscular action.

The invention consists in positioning skin sensors on the patient allowing the detection of signals selected physiological parameters, to process the detected electrical signal and to command the triggering of a sequence of pulses as a function of the result of this processing, for example by exceeding a threshold.

The sequence of electro-stimulation signals has a pulse frequency between 0.5 Hz and 200 Hz.

If the physiological signal is an ECG signal, the electrical level is of the order of a millivolt. Signal processing includes amplification, filtering and sampling, for example at a sampling frequency between 5 and 15 kHz.

Digital filtering eliminates high frequency signals secondary to muscle activity other than cardiac and interference from electrical devices. A low frequency filter makes it possible to reduce the undulations of the baseline secondary to respiration.

In the case of the detection of surface electromyography signals (surface EMG), the electrodes which collect the signal are placed directly on the skin facing the muscle to be studied. This detection consists in recording the electrical activity of muscles and nerves.

Description of an example of stimulation system

Figure 1 illustrates the use of a stimulation system for the implementation of the invention.

It comprises an electronic box (1) comprising an electronic circuit for measuring and controlling the electrical pulses applied by means of electrodes, as well as a set of electrodes.

These electrodes include:

a patch (2) having on its surface two measuring electrodes (3, 4). These electrodes are connected to the EMG signal measurement input, and are placed on the patient's expiratory muscle area

- a pair of abdominal stimulation electrodes (5; 6)

- a pair of pelvic stimulation electrodes (7; 8)

- a ground reference electrode (9).

The electronic unit (1) also communicates with connected computer equipment, for example a computer (10), a tablet (11) or a cellular telephone (12) to receive the information acquired and processed by the unit (1) and for transmit adjustment parameters.

Typology of physiological signal sensors

The sensors intended for the acquisition of physiological signals of muscular biological feedback are according to the chosen variants:

Cutaneous electric electrodes physically separate from the electrical stimulation electrodes, for example conductive tablets placed on a support capable of being applied against the skin and maintained by a biocompatible adhesive, a strip; or textiles

intelligent integrating wires or conductive pads

One or more dual-function electrodes, used alternately for signal pickup

physiological and the application of a signal

electrostimulation. In this case, the electronic circuit comprises a chopper with two electronic switches making it possible to connect the common electrode alternately to the input and to the output of the circuit.

A balloon equipped with a pressure sensor, delivering a signal depending on the effort exerted by a muscle.

A multidirectional inertial sensor secured to a skin electrode. Typology of stimulation modes

Electrical stimulation via conductive electrodes applied to the patient's skin in the vicinity of the muscle to be rehabilitated can be replaced by

haptic stimulation applied by a transducer

electromagnetic on the patient's skin in the vicinity of the muscle to be rehabilitated.

It can also be applied by a pulsed magnetic field, applied in the vicinity of the muscle to be rehabilitated.

The electric electrodes are then replaced by a device for local magnetic stimulation, comprising at least two magnetic coils, which are

connected to the stimulator via a power module to generate the pulsed current with a current adapted to the magnetic coils.

This solution is an alternative to

functional electrostimulation, in which a muscle or nerve is electrically stimulated via contact electrodes in order to effect a muscle contraction in order to support or replace certain physiological processes. Functional magnetic stimulation causes muscle contraction, triggered without contact by appropriate magnetic fields.

The application device for pelvic muscles can take the form of a chair, the seat of which incorporates the magnetic coils.

Description of the electronic circuit

Figure 2 shows a schematic view of the electronic circuit.

It includes a battery (20) which supplies a generator and voltage controller circuit (21). This circuit (21) receives as input the measurement of the transcutaneous resistance measured by the measurement electrodes (3, 4) and produces a control voltage V _totai such that:

Or

- R _3.4 denotes the transcutaneous resistance measured by the measuring electrodes (3, 4). This value is typically of the order of 500 ohms

- I _stim designates the stimulation current level set by the practitioner.

This voltage supplies a circuit composed of 4 electronic switches, in particular of 4 thyristors (22 to 25) which makes it possible to control the passage of the stimulation voltage either in one direction, when the switches (23 and 25) are closed, or in the opposite direction when the switches (22 and 24) are closed.

This thyristor bridge is connected to a load shedding circuit (26) controlling the voltage V _diest so that

Where V _stï designates the level of voltage absorbed by the patient through the electrodes with regard to the current which is set by the practitioner.

This tension depends on the complex behavior of the impedance of the tissues of the individual, the global circuit relieves and limits the applicable tension to eliminate the peaks of tensions resulting from this complex relation. The classic complex element will produce an initial peak which will descend towards the nominal voltage. This peak is both unpleasant and difficult to control. This arrangement makes it disappear or greatly limits it.

This load shedding circuit (26) is connected to a current controller (28) via a fuse (27).

This current controller (28) controls a slope of current with respect to the setpoint, for a time evolution with a first period of increase in current, then of hold at a current plateau, then decrease the current to 0.

In the case of magnetic stimulation, a power module converts the electrical stimulation signals into pulsed electrical signals supplying the magnetic coils.

Qualitative indicator

Alternatively, the intensity of the physiological biological feedback signal is recorded with

stimulation and the intensity of the physiological signal of

biological feedback without stimulation to calculate the difference of the two intensities over a given time period and calculate a qualitative indicator.

According to another variant, during an application period, an electrical signal of

stimulation on the same muscle area (either by

separate and neighboring electrodes, either by an electrode common to stimulation and the collection of the physiological biological feedback signal), the difference in intensity between the physiological biological feedback signal and the stimulation signal is recorded, to calculate a profile representative of the degree of rehabilitation.

These indicators are used to control a visual indicator, for example a series of LEDs activated according to the level of the difference signal, or a graphic indicator.

Claims

claims

1 - Muscle stimulation system comprising a generator of electrical signals, at least one electrode for applying a skin stimulation signal and a means of triggering the emission of an electrical stimulation signal characterized in that it also comprises at at least one sensor for detecting a physiological signal of muscular biological feedback, said electrical signal generator being controlled by a computer to trigger the generation of a stimulation pulse sequence with a frequency between 0.5 Hz and 200 Hz, during the detection by said computer of said physiological signal of muscular biological feedback in the absence of stimulation. 2 - Muscle stimulation system according to claim 1 characterized in that it comprises radiofrequency communication means for the transmission of stimulation information and of detection of physiological signals to remote equipment.

3 - Muscle stimulation system according to claim 1 characterized in that it further comprises a multidirectional inertial sensor secured to a skin electrode.

4 - Muscle stimulation system according to claim 1 characterized in that it comprises a plurality of outputs delivering the same stimulation signal, for the connection of a plurality of electrodes for simultaneously re-educating several muscle groups.

5 - Muscle stimulation system according to claim 1 characterized in that it comprises means for transcutaneous vibration stimulation from 30 to 100 Hz supplied by said stimulation signal.

6 - Muscle stimulation system according to claim 1 characterized in that it comprises means for transcutaneous magnetic stimulation from 30 to 100 Hz comprising magnetic coils supplied by said stimulation signal.

7 - Muscle stimulation system according to claim 1 characterized in that a first series of electrical electrodes for the application of said pulse sequences and a second series of different skin electrical electrodes for the detection of a signal physiological biological feedback.

8 - Muscle stimulation system according to the preceding claim characterized in that said first series of electrodes and said second series of skin electrodes are arranged on the same skin support.

9 - Stimulation method consisting in applying to the patient's skin sequences of stimulation pulses characterized in that the triggering of a sequence of pulses is activated by the detection of a physiological signal of biological feedback by at least one skin sensor, the pulse frequency being between 0.5 Hz and 200 Hz.

10 - Stimulation method according to claim 9 characterized in that said physiological biological feedback signal is detected by the series of skin electrodes used for the application of said pulse sequence, the method comprising a step for extracting from the signal measures the information correlated to said sequence of pulses. 11 - Stimulation method according to claim 9 characterized in that the triggering and the maintenance of a sequence of pulses is controlled by the signal delivered by the sensor for detecting a physiological signal of biological feedback in response to an action of the patient, in the absence of stimulation, by skin electrodes detecting an electromyographic surface signal, the frequency of the pulses being between 0.5 Hz and 200 Hz.

12 - A method of muscle stimulation according to claim 9 characterized in that one controls the recording of the intensity of the physiological signal of biological feedback simultaneously with the passage of stimulation and in that one calculates an indicator function of the difference in the intensity of the physiological biological feedback signal with stimulation and the intensity of the physiological biological feedback signal without stimulation.

13 - A method of muscle stimulation according to claim 9 characterized in that it comprises a step of triggering a sequence of pulses controlled by the detection of involuntary muscle activity in the absence of stimulation and in the absence of action of the patient, by skin electrodes detecting an electromyographic surface signal, the frequency of the pulses being less than 10 Hz.

14 - A method of muscle stimulation according to claim 13 characterized in that the energy of the pulses is a function of the characteristics of the electromyographic signals detected.

15 - A method of muscle stimulation according to claim 9 to 14 characterized in that the pulses are regulated in voltage and current according to the characteristics of the electromyographic signals detected.

16 - A method of muscle stimulation according to claim 9 characterized in that it comprises the acquisition of an electrocardiogram signal and a treatment to cancel in the electromyographic signal the component corresponding to said electrocardiogram. 17 - A method of muscle stimulation according to claim 9 characterized in that it further comprises the generation of a sound signal depending on the detected electromyographic signal. 18 - A method of muscle stimulation according to claim 9 characterized in that it further comprises the control of a light source at the time of stimulation.