Search

Electromyostimulation plays an important role along with other means of rehabilitation and training in sports, clinical and space medicine. Many laboratories in the world are involved in the development of new modes and hardware for electrical stimulation of skeletal muscles and in the study of the physiological effects of electromyostimulation. In the clinical setting, chronic low-frequency, low-intensity stimulation is usually applied with a view to preparing muscle tissue for cardiomyoplastic surgery, correcting the state of a paralyzed muscle, and to rehabilitating patients with the hypokinetic syndrome. This review is devoted to the study of the physiological basis (mechanisms of action) of chronic low-frequency stimulation. In the early 1970s, a model of chronic low-frequency electrical stimulation of the muscles of laboratory animals was developed and widely studied. As a result of numerous studies it was established that such stimulation led to an increase in muscle performance, fatigue resistance, the activities of oxidative enzymes and other structural and metabolic markers, as well as to a sustained fast-to-slow muscle fiber transformation. Similar data were obtained in the studies of healthy volunteers. Low-frequency stimulation had a beneficial effect on the atrophied disused muscle. The review examines the advantages and disadvantages of low-frequency electromyostimulation in relation to deconditioned muscle rehabilitation.

This review addresses the use of robotic devices in the rehabilitation of poststroke and posttrauma patients as a rehabilitation technology which has developed rapidly over the last decade. The types of devices used are described – manipulators and exoskeletons – along with the clinical protocols for their use and the effectiveness of rehabilitation procedures. Particular attention is paid to the neurophysiological basis of the rehabilitation potential of this technology, including analysis of measures of plastic rearrangements of the brain. Results obtained from state-of-the-art rehabilitation technology using hand exoskeletons controlled by brain–computer interfaces based on kinesthetic motor imagery are considered.

The present experiments were designed to gain additionally insight into how the spinal networks process direct spinal stimulation and peripheral sensory inputs to control posture and locomotor movements. We have developed a plantar pressure stimulation system that can deliver naturalistic postural and gait-related patterns of pressure to the soles of the feet to simulate standing and walking, thereby activating and/or modulating the automated spinal circuitry responsible for standing and locomotion. In the present study we compare the patterns of activation among selected motor pools and the kinematic consequences of these activation patterns in response to patterned heel-to-toe mechanical stimulation of the soles of the feet, and/or transcutaneous electrical spinal stimulation, for postural and locomotion regulation. The studies were performed in healthy individuals (n = 12) as well as in subjects (n = 2) with motor complete spinal cord injury. We found that plantar pressure stimulation and/or spinal stimulation can effectively facilitate locomotor output in the subjects placed with their legs in gravity neutral position. We have shown synergistic effects of combining sensory and spinal cord stimulation, suggesting that the two networks are different, but complementary. Also we provide evidence that plantar stimulation could serve as a novel neuro-rehabilitation tool alone or as part of a multi-modal approach to restoring motor function after complete paralysis due to SCI.

The mechanisms underlying the locomotion recovery in poststroke patients remain unknown. Navigated transcranial magnetic stimulation (nTMS) is a new method to evaluate the functional state of the motor system. Using of the “Regent” soft exoskeleton complex (SEC) allow to correct walking pattern significantly. The aim of this study was to evaluate the capability of nTMS to assess changes in gait cortical control using SEC in poststroke patients. 14 patients of the subcortical stroke (the mean age was 53.0 years, the mean time from stroke onset was 14.2 months) received 10 training sessions with SEC. The patients received nTMS before and after the sessions, as well as they were clinically evaluated by the Fugl–Meyer scale section for lower extremity and a 10-m walk test. Whereas a reliable reduction in the time of walking for 10 m was recorded after the sessions with the application of SEC, the Fugl-Meyer scale assessment remained unchanged. During nTMS, a reduction was recorded in the average latency of evoked motor response from the affected hemisphere, as well as various patterns of changes in the size and localization of cortical representations of the leg muscles. We have concluded that the nTMS method allowed us to identify the individual patterns of changes in the cortical representations of leg muscles as a result of the use of SEC in post-stroke patients with injuries in a group of locomotor system elements, thus identifying not only the fact of the undergoing neuroplastic processes, but also their direction.

The space medicine data on the nature of motor disorders suggest an important role of the support inputs in the control of mammalian tonic and postural systems. Progress in functional magnetic resonance tomography (fMRT) makes it possible to perform in vivo analysis of various brain areas during stimulation of the support afferentation. Under these conditions, specific activation of the brain cortical areas was studied in 19 healthy subjects (with the mean age of 38 ± 15.13 years) and 23 patients (with the mean age of 53 ± 9.07 years) with focal CNS lesions (cortical-subcortical ischemic stroke). During scanning of subjects, the support areas of the soles of the feet were stimulated using a block design to simulate slow walking. In healthy subjects, significant activation was recorded (p < 0.05 at the cluster level) in the primary somatosensory cortex, premotor and dorsolateral prefrontal cortex, and insular lobe. In patients that had had a stroke, activation of the locomotion-controlling supraspinal systems clearly depended on the stage of the disease. In patients with a cortical-subcortical stroke, the pattern of contralateral activation of the sensorimotor locomotion predominated during motility rehabilitation.

Methods that, on the one hand, can ensure patient’s mobility and, on the other hand, activate afferent inputs are the main in the rehabilitation treatment. Recent studies have shown that plasticity is the structural basis of recovery after central nervous system lesions. Reorganization of cortical areas, increase in the efficiency of the functioning of preserved structures; and active use of alternative ascending pathways, e.g., intensification of afferent input, constitute the anatomical basis of plasticity. However, sensory correction methods, without accounting of functional condition of patients, may lead to the formation of pathological symptoms: spasticity, hyperreflexia, etc. So, the main aim is to study adequate management of the neuroplasticity process. This problem cannot be solved without modern methods of neuroimaging and brain mapping. The new approach for the study of cortical mechanisms of neuroplasticity, responsible for locomotion, was developed in the present study. This approach is an integrated use of functional magnetic resonance imaging (fMRI) and navigation transcranial magnetic stimulation (nTMS). It has been shown that vast fMRI activation area in the first and second sensorimotor areas emerges with a passive sensorimotor paradigm usage that imitates backing load during walking. The Korvit mechanical stimulator of backing zones of footsteps is used to create this paradigm. The nTMS examination used after fMRI helps to localize motor representation of muscles which control locomotion more accurately. We assume that the new approach can be used for studying the neuroplasticity process and assessing neuroplasticity changes when taking rehabilitation measures to restore and correct the walking process.

A new method for the activation of spinal locomotor networks (SLN) in humans by transcutaneous electrical spinal cord stimulation (tESCS) has been described. The tESCS applied in the region of the T11-T12 vertebrae with a frequency of 5–40 Hz elicited involuntary step-like movements in healthy subjects with their legs suspended in a gravity-neutral position. The amplitude of evoked step-like movements increased with increasing tESCS frequency. The frequency of evoked step-like movements did not depend on the frequency of tESCS. It was shown that the hip, knee, and ankle joints were involved in the evoked movements. It has been suggested that tESCS activates the SPG (SLN) through in part, via the dorsal roots that enter the spinal cord. tESCS can be used as a noninvasive method in rehabilitation of spinal pathology.

The results of extended comparative research in the effect of hypogravity on the motor system in space flights and ground-based experiments have shown that “dry” immersion (DI) is the most adequate model of microgravity—the time of development, and the volume and depth of structural and functional motor disorders in DI are very close to what is observed in real microgravity. The high intensity and speed of development of hypogravity effects during immersion hypokinesia in comparison with bed rest hypokinesia, differing from DI only by the level of support deafferentation, promoted an insight into the leading (triggering) role of support lessness in the genesis of microgravity-induced syndromes of muscular deconditioning and hypogravitational ataxia. The involvement and pathways of support afferentation within the muscular system were experimentally studied and verified. The mechanisms of the development of changes in the activity of the system mechanisms remain much less investigated. These issues, as well as some new approaches for the elimination of the negative effects of hypogravity, were the subjects of investigation in the program of a complex dry immersion experiment, the results of which are presented in this issue of the journal.

International audience; Dry immersion, which is a ground-based model of prolonged conditions of microgravity, is widely used in Russia but is less well known elsewhere. Dry immersion involves immersing the subject in thermoneutral water covered with an elastic waterproof fabric. As a result, the immersed subject, who is freely suspended in the water mass, remains dry. For a relatively short duration, the model can faithfully reproduce most physiological effects of actual microgravity, including centralization of body fluids, support unloading, and hypokinesia. Unlike bed rest, dry immersion provides a unique opportunity to study the physiological effects of the lack of a supporting structure for the body (a phenomenon we call 'supportlessness'). In this review, we attempt to provide a detailed description of dry immersion. The main sections of the paper discuss the changes induced by long-term dry immersion in the neuromuscular and sensorimotor systems, fluid-electrolyte regulation, the cardiovascular system, metabolism, blood and immunity, respiration, and thermoregulation. The long-term effects of dry immersion are compared with those of bed rest and actual space flight. The actual and potential uses of dry immersion are discussed in the context of fundamental studies and applications for medical support during space flight and terrestrial health care.

Movement control in microgravity is complicated by several factors: changed physical properties of the body and extremities, functional proprioceptive deprivation due to reduction of the input from proprioceptors of postural muscles, and increased excitability of the motor control structures. These factors cause complex disturbances of co-ordination of aimed voluntary movements, which are known as hypogravitational ataxia (Kozlovskaya, 1988) and manifest by reduced accuracy and altered movement kinematics.