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Russian Journal of Biomechanics
BIOMECHANICAL AND ELECTROMYOGRAPHIC ASPECTS OF THE RESTORATIVE TREATMENT IN PATIENTS WITH SPINAL CORD INJURIES BY MEANS OF PHASE ELECTRICAL STIMULATION OF
MUSCLES DURING WALKING
Department of biomechanics and control of movements of the Federal Centre for Expertise and Rehabilitation of Invalids of the Ministry of Labour and Social Development of Russian Federation, 3, Ivan Susanin street, 127486, Moscow, Russia, e-mail: [email protected]
Abstract. The course of artificial correction of movements by means of functional electrical stimulation has been carried out in patients with consequences of the spinal cord injuries in the lumbosacral level. Peculiarities of motor disturbances have been established with the heip of clinical and instrumental investigations. The course of electrical stimulation of muscles consisted of 20 sessions. Muscles-extensors of the hip and knee joints have been the main subjects of stimulation. As a result of the course of functional electrical stimulation the following changes have been revealed: improvement of the anthropomorphous properties of walking, increase of walking velocity, cadence and step length, decrease of fatiguability, growth of force and electrical activity of muscles during development of the maximal effort, partial normalisation of biomechanical and innervative gait structure. Besides, restoration of function of the pelvic organs has been also observed in most of patients as a result of the course of functional electrical stimulation. Excellent results have been received in 6 % of all cases, good results - in 83 %, and satisfactory - in 11 %.
Key words: biomechanical and innervative gait structure, patients with spinal cord injuries, artificial correction of movements by means of phase electrical stimulation of muscles
The spinal cord injury belongs among the most severe human sufferings. A complex of structural and functional changes that take place in injuries of the spine and spinal cord are very complicated and varied. These changes are manifested by the expressed motional, sensitive disorders and by the disturbance of function of the pelvic organs.
Trauma of the lumbar region of the spinal cord comprises 48-76 % of all spinal cord injuries and as a rule leads to flaccid pareses of the lower extremities, what makes walking impossible or considerably difficult for a patient [1,2].
At present electrical stimulation of muscles has been applied more and more often in the process of the restorative treatment of patients with locomotor disturbances. With the help of this method it is possible to slow down, and sometimes to prevent the atrophic processes, which develop in the muscle tissue.
For the last ten years both in our country and abroad a fundamentally new method has been used for rehabilitation of patients with spinal cord injuries - functional electrical stimulation of muscles (FES). The essence of this method is that FES is applied as a way of
A.S. Vitenson, Y.M. Mironov, K.A. Petrushanskaya
Introduction
restoration of not the separate organ - a muscle, but the total locomotor act, for example -human walking.
This main feature of functional electrical stimulation determines its main peculiarities.
1) FES is switched out in the definite phases of the locomotor cycle, corresponding to phases of natural excitation and contraction of muscles;
2) not one, but a lot of muscles of the extremities and trunk are the subjects of FES; for all this influence of electrical current, inconsiderable in power causes release of energy of remarkable power;
3) as a result of strengthening of the weakened muscles and correction of wrong-fulfilled movements a motional stereotype, approaching to a normal one, is gradually formed.
Artificial correction of movements is one of the versions of FES. The deficit of a muscular function, causing the disorder of biomechanical gait structure, is the main indication for prescription of artificial correction of movements. At the same time contraindications are common for electrical stimulation.
Usually this method is applied in patients with the partial or complete disruption of the spinal cord in the thoracic region [3-5]. The latter approach derives from the fact that though the spinal control is lost in the given level of injury, but nevertheless ability of muscles to excitation and contraction by means of electrical irritation is still retained.
The other situation is observed in injury of the lumbar region of the spinal cord and cauda equina. In this case flaccid pareses and paralyses are developed with sharp decrease of electroexcitability and remarkable muscle atrophy, what creates considerable difficulties for realisation of FES. Only several reports about possibility of application of FES in flaccid pareses can be found in the literature, for example, in patients with consequences of poliomyelitis [6, 7].
That is why the problem of restoration of the motional functions in the distal injuries of the spinal cord by means of phase electrical stimulation is so actual.
Material and methods
117 patients aged from 20 to 40 with duration of trauma from 2 to 5 years were under clinical observation. Motional disorders, marked in all cases, and changes of functioning pelvic organs (93% of all cases) were the leading disorder in clinical picture of patients.
The state of the supporting motor apparatus and structure of walking have been estimated with the help of a complex of biomechanical and electromyographic investigations.
Biomechanical investigations assumed determination of the muscle force with the help of strain-gauge, establishment of the gait structure by means of recording its temporal, kinematic and dynamic characteristics.
Electromyographic investigations included changes of electrical activity of muscles during development of the maximal effort, revealing EMG-pattern of muscles during walking and quantitative estimation of the average electrical activity of muscles for the locomotor cycle.
Clinical and biomechanical investigations of muscles have been carried out in 22 patients with consequences of spinal cord injuries in the lumbosacral region.
Results of investigations
Biomechanical and innervative gait structure
According to the muscular status all patients were divided into two clinical groups. The following features were characteristic of the first group: the pronounced paresis of hip-extensors, relative safety of muscles-flexors, inconsiderable decrease of function of knee-
extensors and paresis of shank and foot muscles. Besides, these patients walked on the slightly bent at knee and hip joints' limbs with dangling of the feet in the swing phase of the step.
Patients with more severe disturbances of the muscle apparatus comprised the second group. In this group of patients the pronounced paresis of knee-extensors and paralysis of the shank and foot muscles were examined in parallel with the remarkable paresis of hip-extensors and hip-adductors. Patients of this group walked very slowly, without knee-flexion in the stance phase and with dangling of the feet in the swing phase.
The biomechanical data have confirmed justice of division of all patients into two clinical groups in accordance with the value of occurrence of pareses. At the same time they revealed that walking of patients of both of these groups considerably differs from norm. The main characteristics of walking become much worse, mean velocity is reduced in 2.2-2.7 times, step length is diminished in 1.6-1.7 times simultaneously with increase of duration of the locomotor cycle in 1.5-1.6 times.
Besides, the temporal step structure also changes: duration of heel and forefoot support is shortened, but duration of the foot-flat support and of the double support is remarkably increased (Table 1).
However, the most essential difference between two categories of patients takes place in kinematic and dynamic gait structure.
Table 1. Main and temporal parameters of walking in norm and in patients with consequences of _____spinal cord injuries in the lumbosacral region.
Parameters of walking Norm, n=10, M±m Patients of the I group, n= 10, M±m % to norm P Patients of the II group, n= 10, M+m % to norm P
Heel-support interval, % 7.6±0.6 5.8±0.52 76 0.95<P<0.98 5,8±0.82 76 0.9<P<0.95
Foot-flat support interval, % 37.6±0.7 49.1+3.6 131 0.99 <P< <0.998 52.0±2.6 138 P> 0.998
Forefoot support interval, % 19.7±0.6 11 0±0.58 56 P>0.998 12.7±0.78 64 P>0.998
Swing phase, % 35.1±0.9 34.1±0.9 97 0.5<P<0.6 29.4±2.8 84 0.9<P<0.95
x-interval, % 9.3±4.2 -4.1±0.76 - - -3.6±0.74 - -
Double- support phase, % 26.0+1.3 35.5+2.0 137 P> 0.998 38.6±2.1 148 P> 0.998
Walking velocity, m/s 1.14±0.08 0.52±0.03 46 P> 0.998 0.42±0.03 37 P> 0.998
Stride length, s 1.23±0.02 1.87±0.02 152 P>0.998 1.95±0.02 159 P> 0.998
Step length, m 0.69±0.03 0.43±0.01 62 P> 0.998 0.42±0.03 61 P> 0.998
Note: here double-support phase is given as a sum of double-supports at the beginning and at the end of the stance phase.
Walking on slightly bent legs is peculiar to the first group of patients. In Figures, such walking is expressed in some displacements of all curves upward from the zero line, which corresponds to standing with the straighted legs. Other peculiarities of this curves are: more rapid completion of the I plantar flexion at the ankle joint, knee-flexion in the stance phase, reduction of the II plantar flexion and absence of the II dorsal flexion: the latter one means that dangling of the foot is examined from the end of the stance phase and during all the swing phase. In spite of this fact, the usual sequence of movements at the main joins of the extremity remains (Fig. 1).
The ground reaction forces are characterised by considerable decrease of maximums of the vertical component (Rz) lower the body's mass because of the partial unloading on canes, flattening of the extremums of this curve, diminution of maximums of the longitudinal component (Rx) in phase of push-off (See Fig. 1).
But changes of EMG-pattern of muscles of the lower extremities are most expressed.
Three types of changes have been revealed in electrical activity of muscles: 1) sharp reduction of maximums of activity of muscles simultaneously with constant minimal activity; 2) increase of maximums of activity and their considerable prolongation for the most part of the stance phase in parallel with inconsiderable rise of the level of the minimal activity; 3) some decrease of the maximal and remarkable growth of the minimal activity as a result of which a similar level of values is established during the locomotor cycle (Fig. 2, Table 2).
So, the first type — sharp reduction of maximums of activity in parallel with constant minimal activity points to the relative deficit of a muscular function, connected with weakening of the musculovascular afferentation from the extremity during walking. Such change of activity is observed during immobilisation of the extremity's joints [8], during walking on the above- and below-knee prostheses [9].
Probably, paresis of muscles and disorder of movements at the extremities' joints creates conditions, causing weakening of the afferent inflow to the central nervous system.
Table 2. Average electrical activity of muscles of the lower extremities in norm and in patients with
consequences of spinal cord injuries in the lumbosacral region.
Muscles Norm M±m Patients of the I group, n=10, M±m % to norm P Patients of the li group, n=10, M±m % to norm P
m. tibialis anterior 39±2.7 32±1.1 82 0.95 <P< <0.98 - - -
m. gastrocnemius medialis 31 ±1.5 17±1.0 55 P> 0.998 - - -
m. vastus lateralis 16±1.3 28±3.8 175 0.99<P< <0.998 35±4.1 219 P> 0.998
m. semitendinosus 17±1.2 35±1.7 206 P>0.998 24±1.7 141 0.99<P<0.99 8
m. rectus femoris 13±1.0 33±3.9 254 P>0.998 30±2.8 231 P> 0.998
m. biceps femoris 16±1.5 22±1.6 138 0.98<P<0.99 20±1.6 125 0.9<P<0.95
I group
II group
a"
Fig. 1. Change of biomechanical parameters during the locomotor cycle in norm (solid line) and in patients with consequences of spinal cord injury (dotted line). HA - hip angle, KA -knee angle, AA - ankle angle, Rz - vertical component of a ground reaction force, Rx -longitudinal component of a ground reaction force, Rz' - support on crutches or cane.
Î group
m. tibialis anterior
mkV
li group
! group
II group
m. semitendinosus
0 20 40 60 80 100 t, %
m. gastrocnemius mediaiis
mkV
60 40 20
0 20 40 60 80 100 t, % mkV
m. vastus lateralis
- mkV
0 20 40 60 80 100 /, % 0 20 40 60 80 100 % 0
,mkV 60 ■ mkV
60
40 / \ 40 i / -
20 20 Xl^yj"
0 20 40 60 80 100 t, % 0 20 40 60 80 100
m. rectus femoris
60 , mkV 60 ,mkV
40 x » 40
20 \ 20 \
V^v^NV /
0 20 40 60 80 100 t, % 0 20 40 60 80 100
m biceps femoris
mkV mkV
40 40 \-
20 \ * * * * -, /. 20
ii i i i...
20 40 60 80 100 t, % 0 20 40 60 80 100 t, %
Fig. 2. EMG-pattern of muscles of the lower extremities during the locomotor cycle in norm (solid line) and in patients with consequences of spinal cord injury (dotted line).
The second type (high prolonged activity) is very characteristic of walking of patients with infantile cerebral palsy [10], but it is possible to induce it artificially by knee-flexion with the help of the orthopaedic device during walking of the healthy examinees on the slightly bent legs [11]. In this case the increased activity of m. quadriceps femoris may be explained by the flexion position of the lower extremities during walking of patients of the first group, or by tendency to this position in patients of the second group because of weakening of muscles-extensors of the hip joint.
At last, the third type of changes of muscles, peculiar to biarticular muscles (m. semitendinosus and m, biceps femoris) - almost constant remarkable activity during the locomotor cycle should be considered as participation of these muscles in both of the step phases: in the stance phase their work is necessary for hip-extension, and in the swing phase their work is intended for knee-flexion in case of weakening of m. gastrocnemius, which usually takes part in realisation of the push-off.
Consequently, all changes of EMG-pattern reflect only the compensatory reconstruction of muscle work as applied to a new biomechanical structure of walking of patients.
Artificial correction of movements by means of phase electrical stimulation
A deficit of a muscular function (DMF) is the main indication for prescription of artificial correction of movements in patients with the spinal cord injury. This DMF is first of all the absolute one by its origin, because it is connected with the injury of the neuromuscular structures. But besides the absolute deficit, the relative DMF is always present. The latter one is conditioned by a change of afferentation from the extremity in connection with disorder of the posture characteristics of the extremities (contractures and pathological positions at joints).
Artificial correction of movements by means of multichannel electrical stimulation of the paretic muscles is one of the ways to reduce a DMF.
Muscles-extensors of the hip and knee joints must be the preferential subjects of stimulation, because their work is directed to displacement of the body and provision of stability during walking, and the stance phase of the locomotory cycle is considered to be the main one for stimulation of hip- and knee-extensors. Phases of FES must coincide with phases of natural excitation and contraction of muscles, because such electrical stimulation promotes correction of wrong-fulfilled movements and formation of a new stereotype of walking, approaching to a normal one.
Stimulation of muscles-flexors is believed to be the subsidiary correction, because muscles-flexors mainly influence on walking parameters during the swing phase of a step.
As a result of investigations it has been established that the following parameters of walking are the optimal ones in the limits of the comfortable zone: the sequence of right-angled electrical pulses with voltage to 60 V (or current intensities to 250 mA), duration -from 100 to 200 mks, frequency - 30-40 Hz. Choice of temporal program was determined by EMG-pattern of muscles. Angular displacements at knee and hip joints are used for synchronisation of the stimulation pulse with the phases of the step. Electrical stimulation of muscles has been carried out with the help of 8-channel computer-controlled stimulator. This corrector provides adaptation of the temporal program to walking cadence.
Biomechanical and electromyographic effects of artificial correction of movements by means of FES
As a result of 20-day course of electrical stimulation of muscles in 22 patients with flaccid paresis of the lower extremities the following changes of muscle status and gait structure have been revealed:
1) augmentation of strength of muscles-extensors of the hip and knee joints on 35-40 %, and their maximal electrical activity -on 46-31 % (Figs. 3, 4);
2) optimisation of the main characteristics of walking: growth of walking cadence - on 14-17 %, rise of the step length - on 14-17 %, enhancement of mean velocity - on 22-31 %;
3) normalisation of the temporal gait structure: growth of duration of the swing phase on 15 % and reduction of duration of the double support phase, increase or inversion of T-interval, what points to growth of stability of patients during walking;
4) improvement of the kinematic pattern of walking: increase of an amplitude of movements at all joints of the extremity, reduction of dangling of the feet in the swing phase of the step, disappearance of recurvation at a knee joint in patients of the second group (Fig. 3);
5) growth of the extremal values of ground reaction forces: for Rz component - on 15-16 % (front push) and on 6-4 % (push-off), for Rx component - 35-26 % (front push) and 24-11 % (push-off), reduction of loading on the additional support (Fig. 3);
6) enhancement of the maximal electrical activity of muscles on 39-21 % and of the average electrical activity for the locomotory cycle - on 17-18%, more clear EMG-pattern of muscles during walking (Fig. 4);
7) tendency to decrease of energy expenditures, measured by means of indirect calorimetry -on 65 % (Table 3);
8) improvement of the functional state of pelvic organs.
So, the following results may be considered as the main ones after the course of FES: improvement of the anthropomorphous properties of walking, its greater stability, lesser necessity of the additional support during walking, ability for locomotion with greater velocity, normalisation of function of urinary organs and intestine.
The results of treatment of 440 patients with consequences of spinal cord trauma for the last 15 years are given in Table 4.
From the above-cited data one can see high efficiency of the proposed method of rehabilitation of invalids of this profile.
group
HA a°
KA a° 60
40
20
0 20 40 60 80 100 t, % 0
AA a0
II group
group
II group
80 100 t, %
Fig. 3. Changes of biomechanical parameters during the locomotor cycle in patients with consequences of spinal cord injury before (dotted line) and after (solid line) the course of correctional training. Note: all signs are the same as in Fig. 1.
i group
I! group
group
II group
60 40
20
m. tibialis anterior
mkV
0 20 40 60 80 100 t, %
m. gastrocnemius medialis
mkV
60
40 20
0 20 40 60 80 100 t, % mkV
m. vastus lateralis
mkV
60 '
mkV
m. semitendinosus
,mkV 60 '
40
20
0 20 40 60 80 100 t, % 0 20 40 60 80 100 t, % mkV
m. rectus femoris
m
60 '
40 20
0 20 40 60 80 100 t, % 0 20 40 60 80 100 t, %
mkV
m. biceps femoris mkV
40 20
0 20 40 60 80 100 t, % 0 20 40 60 80 100 % 0 20 40 60 80 100 t, % 0 20 40 60 80 100 t, %
Fig. 4. EMG-pattern of muscles of the lower extremities during the locomotor cycle in patients with consequences of spinal cord injury before (dotted line) and after the course of correctional
training (solid line).
Table 3. Influence of the course of correctional training on energy expenditures during
walking in norm and in patients with consequences of spinal cord injuries.
Indicators Norm (n= 10) Patients (n= 10)
Before the course After the course P
Consumption of 02, ml/min*kg 12.6 12.0 12.1 -
Consumption of 02, % 100 95.2 96.0 -
Q1, cal/kg*step - 2.02±0.19 1.73±0.2 0.6<P<0.7
Q1, % - 100 85.6 -
Q2, cal/kg*step*m/s - 6.5±0.94 3.6±0.52 0.98<P<0.99
Q2, % - 100 55.5 -
Velocity, m/s 1.02 0.35±0.02 0.47±0.065 0.9<P<0.95
Velocity, % 100 34.3 46.1 -
Velocity, % - 100 134.3 -
Table 4. Long-term results of treatment by means of functional electrical stimulation of muscles.
Clinical estimation Number of cases, in % Characteristics of gait before the treatment Characteristics of gait after the treatment
Excellent 6 Distance up to 500 m, support on crutches Distance of 5 km without the additional support
Good 83 Distance up to 500 m, support on crutches or on walker Distance about 3 km with the support on one cane
Satisfactory 11 Distance about 300 m, support on walker Distance up to 2 km with two Canadian canes
Conclusions
Combination of the pronounced motional disorders with disturbances of sensibility and function of the pelvic organs is typical for patients with spinal cord injuries in the lumbosacral region.
All patients with consequences of the spinal cord injuries in the lumbosacral region may be divided into two groups in accordance with the muscular status. Strongly pronounced paresis of muscles-extensors and abductors is the common feature for both of these groups; the difference consists in the value of safety of m. quadriceps femoris.
In the first group of patients the function of this muscle is normal or slightly decreased, and in the second group the function of this muscle is sharply reduced.
Walking on legs slightly bent at hip and knee joints, dangling of the feet in the swing phase are typical for the first group of patients; walking on the straightened legs without flexion at a knee joint in the stance phase, with dangling of the feet in the swing phase and using not only canes but crutches as the additional support are characteristic of the second group of patients.
As a whole walking of this category of patients is characterised by the following features: sharp worsening of the main parameters (velocity, step length, cadence), disorder of
the temporal and kinematic step structure (disappearance of some phases of the locomotor cycle, change of the sequence of movements, growth of an amplitude of pelvic swayings), reduction and deformation of the curves of components of ground reaction forces, redistribution of electrical activity of muscles during the cycle. The deficit of function of many muscles, especially extensors, is the basis of all locomotor disturbances.
Artificial correction of movements by means of multichannel electrical stimulation of muscles in combination with application of orthotics normalising the function of the ankle joint is one of the most effective ways for reduction of the deficit of a muscular function. By means of electrical stimulation of m. quadriceps femoris, m. gluteus maximus, m. gluteus medius and m. sacrospinalis it is possible to correct the following movements: extension at knee and hip joints, frontal and sagittal swayings of the trunk.
An amplitude program supposes the use of a sequence of right-angled electrical pulses with frequency from 30 to 40 Hz, duration from 100 to 200 mks and voltage to 60 V (or current intensities to 250 mA). Temporal program of stimulation must correspond to the phases of natural excitation and contraction of muscles.
The twenty-day course of correctional training leads to considerable improvement of the state of the paretic muscles, growth of muscle force and maximal electrical activity.
Under the influence of the course of motional correction the main, kinematic and dynamic parameters of walking improve, average electrical activity for the cycle also increases, especially in phases of development of the maximal effort, as a result of which supportability of the extremity considerably grows and necessity of using the additional support becomes much less.
References
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Москва, Медицина, 1975 (in Russian).
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3. KRALJ A., BAJD Т., TURK R„ KRAJNIK J., BENKO H. Gait restoration in paraplegic patients: a feasibility demonstration using multichannel surface electrode FES. Journal of Rehabiiitation Research and Development, 20(1): 3-20, 1983.
4. SCHWANDA G„ FREY M , HOLLE J., KERN H., MAYZ W„ STOHZ H., THOMA H. 18-month experience in clinical application of implantable multichannel stimulation devices for paraplegic patients. In: Proceedings of the 8-th International Symposium on External Control of Human Extremities, Dubrovnic, 1984, Yugoslav Committee for Electronics and Automation, Belgrade, p. 79-87, 1984.
5. VOSSIUS G., MUECHEN U., HOLLANDER J. Multichannel stimulation of the lower extremities with surface electrodes. In: Proceedings of the 9-th International Symposium on External Control of Human Extremities, Dubrovnic, 1987, Yugoslav Committee for Electronics and Automation, Belgrade, p. 193-203, 1987.
6. ПЕТРУШАНСКАЯ K.A. Влияние электростимуляции мышц при ходьбе на их функциональное состояние у больных с последствиями полиомиелита. Протезирование и протезостроение, сб. трудов, вып. 71, Москва, ЦНИИПП, с. 104-112, 1985 (in Russian).
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8. ВИТЕНЗОН А.С. Физическое моделирование элементов патологической ходьбы. Протезирование и протезостроение, сб. трудов, вып. 55, Москва, ЦНИИПП, с. 28-38, 1980 (in Russian).
9. СЛАВУЦКИЙ Я.Л., БАСКАКОВА Н.В. Особенности электрической активности мышц при ходьбе на протезах после односторонней ампутации. Протезирование и протезостроение, сб. трудов, вып. 27, Москва, ЦНИИПП, с. 10-25, 1971 (in Russian).
10. ЖУРАВЛЕВ A.M., ПЕРХУРОВА И.С., СЕМЕНОВА К.А., ВИТЕНЗОН А.С. Хирургическая коррекция позы и ходьбы при детском церебральном параличе. Ереван, Айастан, 1986 (in Russian).
11. ВИТЕНЗОН A.C. Влияние изменения подвижности в коленном суставе на электрическую активность мышщ бедра при разной скорости ходьбы. Протезирование и протезостроение, сб. трудов, вып. 30, Москва, ЦНИИПП, с. 84-92 (in Russian).
БИОМЕХАНИЧЕСКИЕ И ЭЛЕКТРОМИОГРАФИЧЕСКИЕ АСПЕКТЫ ВОССТАНОВИТЕЛЬНОГО ЛЕЧЕНИЯ БОЛЬНЫХ С ПОСЛЕДСТВИЯМИ ПОВРЕЖДЕНИЯ СПИННОГО МОЗГА ПОСРЕДСТВОМ ФАЗОВОЙ ЭЛЕКТРОСТИМУЛЯЦИИ МЫШЦ ПРИ ХОДЬБЕ
A.C. Витензон, Е.М. Миронов, К.А. Петрушанская (Москва, Россия)
Для больных с последствиями повреждения спинного мозга в пояснично-крестцовом отделе типично сочетание выраженных двигательных расстройств с нарушением чувствительности тазовых органов.
По своему мышечному статусу больные могут быть разделены на две группы. Общим для обеих групп является выраженный парез мышц-разгибателей и абдукторов бедра: различие состоит в степени сохранности функции четырехглавой мышцы бедра.
В первой группе больных функция этой мышцы сохранена или слегка снижена, во второй существенно ослаблена.
Для больных первой группы характерна ходьба на слегка согнутых в тазобедренных и коленных суставах ногах, отвисание стоп в переносную фазу, для больных второй группы - ходьба на выпрямленных ногах без подгибания в коленных суставах в опорную фазу, с отвисанием стоп в переносную фазу и использованием в качестве дополнительной опоры не только тростей, но и костылей.
В целом ходьбе этой категории больных присущи следующие черты: резкое ухудшение основных показателей (скорости, длины шага, темпа), нарушение временной и кинематической структуры шага (выпадение отдельных фаз двигательного цикла, изменение последовательности движения, увеличение амплитуды раскачивания таза), снижение и деформация кривых составляющих опорной реакции, перераспределение электрической активности мышц в течение цикла. В основе всех локомоторных расстройств лежит дефицит функции многих мышц, главным образом разгибателей.
Одним из наиболее эффективных способов уменьшения дефицита мышечной функции является искусственная коррекция движений посредством многоканальной электрической стимуляции мышц в комбинации с применением ортезов, нормализующих функции голеностопного сустава. Коррекции подлежат разгибательные движения в коленных и тазобедренных суставах, фронтальные и сагиттальные наклоны туловища посредством электростимуляции четырехглавой мышцы бедра, большой и средней ягодичных мышц, крестцово-остистых мышц.
Для коррекции ходьбы следует рекомендовать последовательность прямоугольных электрических импульсов с частотой следования 30-40 Гц, длительностью от 100 до 200 мкс, амплитудой напряжения до 60 В (или силой тока до 250 мА). Временная программа стимуляции должна соответствовать фазам естественного возбуждения и сокращения мышц и задаваться с помощью датчика коленного угла для синхронизации импульсов стимуляции с фазами шага.
Двадцатидневный курс коррекционной тренировки способствует существенному улучшению функционального состояния паретичных мышц: возрастанию силы и максимальной электрической активности мышц.
Под влиянием коррекции движений наблюдается улучшение основных характеристик ходьбы, ее кинематических и динамических параметров, рост средней электрической активности за цикл, особенно- в те его фазы, когда возникает потребность в развитии максимальных усилий, в результате чего резко повышается опороспособность нижних конечностей и уменьшается использование дополнительной опоры. Библ. 11.
Ключевые слова: биомеханическая и иннервационная структура ходьбы, больные с повреждениями спинного мозга, искусственная коррекция движений посредством электростимуляции мышц
Received 14 June 2001
