RU2529471C2 - Method for cutaneous electrical stimulation of spinal cord - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention refers to medicine, namely - to neurology. A region above thoracic vertebrae T11-T12 of a patient lying on his/her side with his/her legs suspended in rocking frame is exposed to an electrical bipolar rectangular stimuli sequence in the form of square waves at frequency 5-40 Hz, length 0.5 ms and carrier frequency 10 kHz. That is combined with an exposure covering cervical C4-C5 and lumbar L1-L2 vertebrae. All the spinal regions are stimulated at the same time at a pulse phase shift in a pulse packet within 0.1-0.5 ms; the amplitude is specified within 40-200 mA so that the procedure induces no pain.

EFFECT: method enables accelerating rehabilitation process, increasing amplitude and improving motion coordination that is ensured by the synchronous stimulation of the various spinal regions in a combination with the natural physiological stimulation.

2 cl, 1 tbl, 4 dwg, 1 ex

Description

The invention relates to medicine, namely to neurology, and can be used to develop methods for the treatment and rehabilitation of people with spinal cord lesions.

One of the methods to obtain a good result in the restoration of motor functions in spinal patients is electrical stimulation of the spinal cord, aimed at calling step-like movements of the patients legs.

Known US patent No. 5002053, IPC A61N 1/00, publ. 1991, which describes a method and device for calling locomotion in paralyzed patients by applying electrodes to the surface of the spinal cord. These solutions, subject to the appropriate conditions for electrical exposure and the selection of certain areas of electrode application, cause active movements of the lower limbs of patients.

A known method of treating patients with a lesion of the spinal cord according to US Pat. RU No. 2204423, IPC A61N 1/36, publ. 2003. The method is based on electrical stimulation of the lumbar thickening of the spinal cord of a person. Stimulation is carried out by electrodes superimposed on the dura mater of the spinal cord. Such stimulation causes leg movements when the patient is in a lighter position, lying on his back or side with his legs suspended in the Balkan frames.

A known method of modeling the treatment of patients with chronic damage to the spinal cord according to US Pat. No. 2418319, IPC A61N 1/32, publ. 2009.

The method consists in the simultaneous electrical stimulation of two segments of the spinal cord below the lesion site, which not only causes locomotor movements of the lower extremities, but also leads to the emergence of a support function for the patient’s body.

However, all of the above methods for treating patients with chronic spinal cord lesions are invasive and consist of applying stimulating electrodes directly to the surface of the dura mater of the spinal cord (epidurally), followed by electrical stimulation of the latter below the level of its damage. The implementation of these methods requires surgical intervention to implant electrodes into the intervertebral space on the surface of the patient’s spinal cord, which is quite painful and unsafe for the patient.

The closest analogue of the proposed solution is the method described in the article author. Gorodnicheva P.M. et al. “Percutaneous electrical stimulation of the spinal cord: a non-invasive method of activating the generators of walking movements in humans”, g. "Human physiology." - M .: Nauka, 2012, T. 38, No. 2, P. 46. The advantage of the prototype is its non-invasiveness and the associated less painful and traumatic treatment of people with vertebrospinal pathology. The essence of the method lies in the fact that the locomotor movements of the lower extremities of the patient are caused as a result of the cutaneous, and not epidural, effect on the T11-T12 region of the spinal cord with a series of electric stimuli with the patient legs lighter.

As a device that implements the known method, was used an electric stimulator "Coulomb", developed by FSEI VPO "SUAI". An active electrode in the form of a disk made of conductive plastic was placed along the midline of the spine at the level of the thoracic vertebrae T11 and T12 between the spinous processes, passive electrodes - rectangular plates were placed symmetrically on the skin over the iliac crests. To call step-like movements, rectangular bipolar stimuli were applied in the form of meanders with a duration of 0.5 ms with a carrier frequency of 10 kHz and an amplitude of 0-70 mA for 10-20 seconds.

The disadvantage of the prototype is the lack of activity and severity of stimulated movements. Studies have shown that locomotor movements caused by the method described above have a limited amplitude in all joints, while not all of the subjects participated in the total movement of the ankle joint. Thus, during electrical stimulation of the spine in the T11-T12 region, the ankle joint was involved in movement in only 50% of cases in 4 out of 5 subjects, due to which the induced movements of the lower extremities of the subjects had inadequate coordination of movements in the joints, different from the natural coordination characteristic of normal walking.

The inventive method allows to obtain a new technical result compared to the prototype, which consists in increasing the activity and coordination of the movements caused by increasing the likelihood of involving the ankle joint in the total movement of the legs and increasing the amplitude of movements in all joints.

To achieve the specified result in the method of cutaneous electrostimulation of the spinal cord (including, like the prototype, exposure to a sequence of electric rectangular bipolar stimuli in the form of meanders with a frequency of 5-40 Hz, a duration of 0.5 ms and a carrier frequency of 10 kHz per region above the chest vertebrae T11-T12 of a patient placed “lying on his side”, with legs suspended in a swing frame, in contrast to the prototype, additionally carry out an impact in the cervical region C4-C5 and lumbar L1-L2 vertebrae, while stimulation of odyat simultaneously all regions of the spinal cord with shift pulses supplied stimuli in a pack in phase - in the range 0.1-0.5 ms, and the amplitude selected in the range 40-200 mA so that the procedure did not cause pain.

The selected areas and parameters of electrical stimulation of the spinal cord allow you to activate the work of all joints of the lower extremities of a person and increase the amplitude of the caused movements to normal, which is typical for natural coordinated walking. However, only with cutaneous stimulation of the spinal cord of a patient who is in the “lying on his side” position with his legs suspended in a swing frame, the procedure is safe.

The result obtained during the research showed that during electrical stimulation of 3 segments of the spinal cord at the level of the vertebrae T11-T12, C4-C5 and L1-L2, the increase in the amplitude of the caused movements and the involvement of all joints in the movement does not occur due to the linear addition of the results of individual types of exposure , and due to their increase - synergy, which is a consequence of the simultaneous activation of various neural networks of the spinal cord.

The indicated effect was revealed and confirmed during electrical stimulation sequentially at one, two and three levels of the spinal cord.

1. Conducted stimulation at the same level, alternately stimulating the T11, C5, L2. The stimulus intensity was selected individually for each subject taking into account the level of stimulation, increasing the strength of the current until the procedure began to cause the subject pain or other unpleasant sensations - this current was considered the maximum. Then, the zone was stimulated for 15 seconds using the submaximal current amplitude. Stimulation at the T11 and L2 levels caused involuntary leg movements similar to walking, the ankle joint was involved more often with L2 stimulation than with T11 stimulation. Stimulation at the C5 level caused lower limb movements in one out of five subjects. The amplitude of the stimulating current (mA), causing the movement, was 80-180 mA.

2. Stimulated two levels of the spinal cord. In all cases, they started with stimulation of the T11 level, after 15 seconds, stimulation with C5 or L2 began and continued for at least 15 seconds. The procedure used the same current amplitude as for single stimulation. In this case, the supply of stimuli was organized so that there was no summation of the stimuli, for which the beginnings of the envelopes of the low-frequency components were separated by several microseconds. Synchronous stimulation at the level of two vertebrae caused involuntary leg movements in all subjects. With double synchronous stimulation, it was noted that the range of motion is greater than with single stimulation, and the ankle joint is involved in movement in 90-95% of cases.

3. Three levels of the spinal cord were stimulated starting at T11, then stimulation of L2 and C5 was added sequentially. The duration of the first stimulation and each additional was 15 seconds. In this case, the supply of stimuli was organized so that there was no summation of the stimuli, for which the beginnings of the envelopes of the low-frequency components were separated by several microseconds. With triple synchronous stimulation, the increase in the amplitude of the induced movements in the joints compared to a single one was up to 300%, and the ankle joint was involved in the movement in all subjects. Since the synchronization of channels used for stimulation of the device was carried out in such a way that the stimuli for each channel followed with a minimum delay relative to each other, the resulting effect cannot be the result of a total increase in the stimulating current with simultaneous exposure, but is the result of the simultaneous activation of different neural networks of the spinal cord brain.

As a device that implements the proposed method, an electro-stimulator is used, containing three galvanically independent decoupled stimulation channels with an electrode system, respectively connected to a signal control unit, a microcontroller with software, a signal conditioner, to amplitude and indication measuring units, and to a power supply unit.

The exposure is carried out through electrodes superimposed on the patient's skin with a sequence of rectangular electric bipolar stimuli in the form of meanders with an amplitude of 40-270 mA, a frequency of 5-40 Hz, a duration of 0.5 ms and a carrier frequency of 10 kHz. The stimulus parameters in each channel and the time delays between stimulus packets in the channels are formed by the controlling microcontroller that implements the stimulation algorithm, individual for each patient. The control unit and the display unit allow you to set the required stimulus parameters and the stimulation session program and memorize them for further use. Galvanic isolation between the channels allows you to place stimulating electrodes according to the desired topological scheme on the patient's body without the risk of spurious uncontrolled stimulation channels.

A comparison of the proposed method and the prototype showed that the task is to increase the activity and coordination of the movements caused by increasing the probability of involving the ankle joint in the total movement of the legs and increase the amplitude of movements in all joints - it is solved as a result of a new set of signs, which proves the conformity of the proposed invention with the criterion patentability "novelty."

In turn, the information search in the field of medicine and electrophysiology did not reveal solutions containing individual distinctive features of the claimed invention, which allows us to conclude that the proposed method meets the criterion of "inventive step".

The essence of this method is illustrated in figures 1-4, where

figure 1 - shows an image of a patient in a "lying on his side" with legs suspended in a swing frame;

figure 2 is a block diagram of a three-channel stimulator;

figure 3 - the results of video recording of angular movements in the hip (B), knee (K) and ankle (D) joints of the right leg in response to electrical stimulation of the spinal cord; abscissa - time from the beginning of the registration of movements; along the left axis of the ordinates - the amplitude of movements in the hip and knee joints; along the right ordinate axis - the amplitude of movements in the ankle joint; arrows 1, 2 and 3 indicate the onset of single (T11), double (T11 + L2) and triple (T11 + L2 + C5) electrical stimulation, respectively;

figure 4 - change in the amplitude of motion in the joints of the legs with single and multisegmental stimulation. Averaging the results obtained for all subjects (table 2). The abscissa is the stimulated ssgment (s). The ordinate is the scaled amplitude. Bdr, Kli, Glnst: hip, knee, golepost, respectively.

The method was implemented using the device (Fig. 1), consisting of two suspension units, one of which is made in the form of an element with a cylindrical surface, which is a bed for the lower leg of one of the legs of the subject, the second - in the form of an element with the same cylindrical surface, which provides leg support of the second leg. The first node is suspended on belts, the second is connected to a horizontally oriented board (1155 × 200 mm, 3 kg) and can freely rotate in a horizontal plane relative to the connection point. The board is suspended on belts at the same point as the first node.

For cutaneous electrical stimulation, a three-channel electrical stimulator was used (Fig. 2), consisting of a control unit 1, a microcontroller 2, an indication unit 3, a signal shaper 4, a unit for measuring the amplitude of the current in channels 5, output stages 6, stimulation channels 7, a network adapter (- 220V / 50/60 Hz / 9V, 1.5A) 8, power supply 9. Using the control unit 1, the required stimulation parameters are set, which are displayed for monitoring on the display unit 3. Microcontroller 2 controls the operation of the signal conditioner 4, which through output stages with gal By isolation, 6 are fed to the stimulating electrodes 7. The current strength in each channel is monitored by the current amplitude measurement unit 5 with subsequent indication. The stimulator is powered through a universal power supply 9, containing a battery that is charged through a network adapter 8.

EXAMPLE OF IMPLEMENTATION OF THE METHOD

The studies were conducted at the experimental base of the Velikiye Luki State Academy of Physical Culture and Sports. 5 physically healthy people were involved in the studies.

The subjects were placed on their left side, the right leg was supported directly in the shin area, and the left foot was located on a rotating tire attached to a horizontally oriented board, held by straps attached to the ceiling (Fig. 1).

Stimulating electrodes (cathodes), each in the form of a disk 2.5 cm in diameter, made of conductive plastic (Lead-Lok, Sand point, USA), were located along the midline of the spine at the level of the cervical (C4-C5), thoracic (T11-T12) and lumbar (L1-L2) vertebrae, between the spinous processes. Indifferent electrodes (anode) - rectangular plates of 5 * 10.2 cm ² (Ambu, Ballerup, Germany) were placed symmetrically on the skin over the iliac crests.

The movements of the lower extremities were caused by rectangular bipolar stimuli with a duration of 0.5 ms, filled with a carrier frequency of 10 kHz, with a stimulation intensity in the range from 40 to 200 mA. The stimulation frequency is 5 Hz, the duration of exposure varies from 10 to 60 seconds. When each stimulus was filled with a high-frequency component, the procedure did not cause pain when the amplitude increased to 100 mA or more. With simultaneous stimulation of all areas of the spinal cord, the supply of stimuli is organized so that there is no summation of the stimuli, for which the beginning of the envelopes of the low-frequency components are spaced 0.1-0.5 microseconds.

To record the movements of the legs, a video system was used (Qualisys, Sweden). Reflective markers were attached to the right leg, to points on the body that coincided with the axes of movement in the shoulder, hip, knee and ankle joints. Angular movements in the hip joint were calculated by the position of the markers located on the lateral condyle of the shoulder, the greater trochanter and the lateral condyle of the thigh. Markers attached to the greater trochanter, lateral condyle of the thigh and ankle were used to assess movements in the knee joint. Displacements in the ankle joint were measured by markers located on the lateral condyle of the thigh, ankle and big toe.

In separate experiments, flexion-extension in the knee joints of both legs of the subject was recorded using goniometers. In the same experiments, the electromyogram of the muscles of both legs was recorded; on m. biceps femoris and m. gastrocnemius superimposed bipolar surface electrodes; EMG signals were recorded using a telemetric electroneuromyograph (ME 6000 MegaWin, Finland).

The reconstruction of the movements of one walking cycle was carried out using the original program. To register the movements of the end point of the foot, the marker was mounted on the big toe of the right foot. Further processing of the results was carried out with a standard set of Microsoft Excel tools.

In table 1 and figure 3, 4 presents the results of the research. The range of motion in the joints was scored. 0 - lack of movement; 1 - the presence of movement; 2 - a noticeable increase in the amplitude of motion in the joint compared with single stimulation recorded in the same study; 3 - increase in the amplitude of movements in comparison with double stimulation recorded in the same study. Designations in the table: Test: test subject; Psv: a vertebra near which stimulation was carried out; Sust: joint; Bdr, Kln, Glnst: hip, knee, ankle, respectively (results related to the ankle are highlighted in the background).

Table 1 Isp / Sust / Pzv C5 T11 L2 T11 + L2 T11 + C5 T11 + L2 + C5 No. 1 Bdr 0 one one 2 2 3 Kln 0 one one one 2 3 Glnst 0 0-1 one 0 one one Number 2 Bdr 0 one one 2 2 3 Kln 0 one one 2 2 2 Glnst 0 one one 2 2 2 Number 3 Bdr one one one 2 2 2-3 Kln one one one 2 one 3 Glnst 0 0-1 one 2 0 3 Number 4 Bdr 0 one one 2 2 3 Kln 0 one one 2 one 2 Glnst 0 0-1 0 one 0-1 2-3 Number 5 Bdr 0 one one 2 2 3 Kln 0 one one 2 2 3 Glnst 0 0-1 one 2 2 3

As a result of the studies, it was found that the use of the claimed cutaneous three-segment electrical stimulation of the spinal cord allows all joints to be involved in the movement of the lower extremities of the subjects and increase the amplitude of the induced movements to a normal value, which makes it possible to bring the movement of the legs closer to the form of natural walking.

The proposed method is intended for use in the physiology of movements for modeling locomotor behavior, for studying the mechanisms of controlling locomotor behavior, as well as in medicine for creating non-invasive methods of treatment and rehabilitation of people with vertebro-spinal pathology. An additional effect of the use of the present invention is the possibility of targeted management of induced walking movements in patients with spinal cord lesions. By stimulating alternately or synchronously different parts of the spinal cord with electrical exposure (local stimulation) simultaneously with natural physiological stimulation, it is possible to activate the natural synergies between the movements of the arms and legs or the movements of the legs (arms) and maintaining equilibrium, which will speed up the process of patient rehabilitation.

Claims (2)

1. A method of cutaneous electrical stimulation of the spinal cord, including exposure to a sequence of electric rectangular bipolar stimuli in the form of meanders with a frequency of 5-40 Hz, a duration of 0.5 ms and a carrier frequency of 10 kHz in the region above the thoracic vertebrae T11-T12 of the patient, placed “lying on its side” ", With legs suspended in a swing frame, characterized in that they additionally act in the region of the cervical C4-C5 and lumbar L1-L2 vertebrae, while stimulation is carried out simultaneously of all areas of the spinal cord with a shift of the impulse s in a stack supplied stimuli in phase within 0.1-0.5 ms, with an amplitude selected in the range 40-200 mA so that the procedure did not cause pain. 2. The method according to claim 1, characterized in that an electric stimulator is used for stimulation, comprising three galvanically isolated stimulation channels with an electrode system, respectively connected to a signal control unit, a microcontroller with software, a signal conditioner, to amplitude measurement and indication units, and a unit nutrition.

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