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Biomedical subjects

L A Chernikova

Publications and source records attributed to L A Chernikova.

At least 19 recordsLinked to original sources
PubMed2005

Supervised learning of postural tasks in patients with poststroke hemiparesis, Parkinson's disease or cerebellar ataxia.

Supervised learning of different postural tasks in patients with lesions of the motor cortex or pyramidal system (poststroke hemiparesis: 20 patients), nigro-striatal system (Parkinson's disease: 33 patients) and cerebellum (spinocerebellar ataxia: 37 patients) was studied. A control group consisted of 13 healthy subjects. The subjects stood on a force platform and were trained to change the position of the center of pressure (CP) presented as a cursor on a monitor screen in front of the patient. Subjects were instructed to align the CP with the target and then move the target by shifting the CP in the indicated direction. Two different tasks were used. In "Balls", the target (a ball) position varied randomly, so the subject learned a general strategy of voluntary CP control. In "Bricks", the subject had to always move the target in a single direction (downward) from the top to the bottom of the screen, so that a precise postural coordination had to be learned. The training consisted of 10 sessions for each task. The number of correctly performed trials for a session (2 min for each task) was scored. The voluntary control of the CP position was initially impaired in all groups of patients in both tasks. In "Balls", there were no differences between the groups of the patients on the first day. The learning course was somewhat better in hemiparetic patients than in the other groups. In "Bricks", the initial deficit was greater in the groups of parkinsonian and cerebellar patients than in hemiparetic patients. However, learning was more efficient in parkinsonian than in hemiparetic and cerebellar patients. After 10 days of training, the hemiparetic and cerebellar patients completed the acquisition at a certain level whereas the parkinsonian patients showed the ability for further improvement. The results suggest that motor cortex, cerebellum, and basal ganglia are involved in voluntary control of posture and learning different postural tasks. However, these structures play different roles in postural control and learning: basal ganglia are mainly involved in learning a general strategy of CP control while the function of the motor cortex chiefly concerns learning a specific CP trajectory. The cerebellum is involved in both kinds of learning.

Adult↗
PubMed2004

Characteristics of learning voluntary control of posture in lesions of the pyramidal and nigrostriatal systems.

The aim of the study reported here was to investigate impairments on the learning of voluntary control of the center of pressures using visual feedback in patients with lesions of the corticospinal and nigrostriatal systems. Participants were 33 patients with Parkinson's disease and 20 patients with hemipareses due to circulatory lesions in the basin of the middle cerebral artery. Subjects stood on a stabilometric platform and used two computer games over 10 days to learn to shift the body relative to the foot to move the centre of pressures, indicated by the position of a cursor on the screen, with the target and to move the target to a specified part of the screen. The games differed in terms of the postural tasks. In one, the direction of movement of the center of pressures was not known to the subjects, and subjects learned a general strategy for posture control; the other formed a strictly defined postural coordination. Both groups of patients were found to have impairments of voluntary control of the position of the center of pressures. There were no differences between groups of patients, in terms of the severity of the initial performance deficit in the task involving shifts of the center of pressures in different directions (the general strategy for controlling the center of pressures), while learning of this task was more difficult for patients with Parkinson's disease. The initial deficit in the fine postural coordination task was more marked in patients with Parkinsonism, though learning in these patients was significantly better than in patients with hemipareses. It is suggested that the mechanisms of involvement of the nigrostriatal and corticospinal systems in learning the voluntary control of posture have elements in common as well as unique elements.

Adult↗
PubMed2004

[Clinical and stabilometric analysis of postural instability in Parkinson's disease].

A disturbance of postural control is one of the most invalidating symptoms of Parkinson's disease (PD), and mechanisms underlying its development have not been so far elucidated. To specify the postural control features in different PD forms, clinico-neurophysiological analysis was conducted in 61 patients divided into 3 groups according to PD forms: tremor-rigid, rigid-tremor and akinetic-rigid. Dissociation between clinical expression of postural instability and its stabilometric reflection--the square of statokinesogram was found, indicating importance of differentiated approach in performance of stabilometric analysis in patients with different PD forms. The square of statokinesogram may be regarded as a neurophysiological marker of postural instability only in patients with rigid forms, in tremor parkinsonian phenotypes an increased square of stabilogram being mainly a stabilometric reflection of tremor. The importance of stabilometric test performance with cognitive loading, allowing switching out of voluntary posture control, is shown. Possible neuromediator mechanisms involved in postural instability in PD are discussed.

Adult↗
PubMed2004

[Voluntary postural control learning with a use of visual bio-feedback in patients with spinocerebellar degenerations].

The study aimed at evaluation of possibility and features of voluntary postural control learning using biofeedback from a force platform in patients with spinocerebellar ataxias. Thirty-seven patients with different forms of spinocerebellar degenerations and 13 age-matched healthy subjects were trained to shift the center of pressure (CP) during several stabilographic computer games which tested an ability to learn 2 different types of voluntary postural control: general strategy and precise coordination of CP shifting. Despite the disturbances of static posture and ability for voluntary control of CP position, patients with spinocerebellar degenerations can learn to control a vertical posture using biofeedback on stabilogram. In contrast to healthy subjects, improvement of coordination in the training process does not exert a significant influence on the static posture characteristics, in particular on lateral CP oscillations. The results obtained suggest involvement of the cerebellum in both types of postural control that distinguishes them from pathology caused by motor cortex and nigro-striatal system involved only in one type of postural control.

Adolescent↗
PubMed2002

[Mechanisms of lability of neurological symptoms in multiple sclerosis].

Pathophysiological peculiarities of demyelinated axons determine their high sensitivity to different exogenous factors and are the reason of instability of neurological signs in MS. One of the typical MS sing is high sensitivity to elevated temperature of the body. Even temporary elevation in body temperature may cause changes in impulse conduction in demyelinated fibres, which was proved by studies of evoked potentials and stabilometric studies. These disturbances may be associated with disorder of ions channels function. The role of other factors (metabolic and immunological disturbances, levels of cytokines and neurotransmitters) in temporary block of nerve conduction in MS is discussed. Further studies of the mechanisms of the lability of neurological sings in MS may lead to elaboration of new approaches to MS treatment.

Adult↗
PubMed1989

[Prevention of contractures in post-stroke arthropathies].

Arthropathies develop in 15-20% of post-stroke paresis patients. A complex of rehabilitative measures including physical therapy (transcutaneous stimulation analgesia, heating etc.), kinesitherapy and anabolic hormones can prevent contractures if applied at the early rehabilitative stage.

Adult↗
PubMed1988

[A method of electromyographic feedback in post-stroke movement disorders].

The authors have investigated the efficacy of training with the help of the method of electromyographic feedback (EMGFB) in 38 patients with post-stroke hemiparesis and the relationships of the training efficacy with the clinical picture of motor disturbances and the status of higher psychic functions. It as been ascertained that the effect of training does not depend on the initial degree of paresis of the trained muscles. Correlation has been established between the capacity of overcoming synergic reactions and concentration of attention, and also the level of working ability. Possible mechanisms of training with the help of EMGFB are discussed.

Cerebrovascular Disorders↗
PubMed1985

[Method of transcutaneous nerve stimulation in the treatment of post-stroke arthropathies].

The authors analyzed the results of treating 75 patients with post-stroke arthropathies by transcutaneous nervous stimulation (TNS) and by some other kinds of low frequency electrotherapy. A method of TNS in post-stroke arthropathies was elaborated. A comparison of the effect of TNS with that of diadynamic (DC) and sinusoidal-modulated (SMC) currents showed no significant advantage of the analgesic action of TNS as against the analgesic action of DC and SMC when used in post-stroke arthropathies. TNS was shown to have a weak effect on tissue trophicity.

Cerebrovascular Disorders↗
PubMed1984

[Method of electromyographic feedback in the complex rehabilitative therapy of patients with post-stroke movement disorders].

The author has developed techniques of staged training by the EMG-biological feedback (EMG-BFB) method with the use of visual and sound control in patients with various degrees of motor disorders. A new variant of the EMG-BFB method (multichannel) is offered which has made it possible to use the method not only for training weakened muscles and reducing spasticity in their antagonists but also for improving motor coordination. A comparative study of the efficacy of the conventional complex of therapeutic exercises and the effectiveness of the therapeutic physical training in conjunction with the EMG-BFB method has demonstrated the latter to be 15% more effective on an average.

Biofeedback, Psychology↗
PubMedDate not supplied

Impairment of learning the voluntary control of posture in patients with cortical lesions of different locations: the cortical mechanisms of pose regulation.

The process of learning to produce voluntary changes in the position of the center of pressures using biological feedback was studied by stabilography in patients with hemipareses due to cerebrovascular lesions in the zone supplied by the middle cerebral artery. There were significant impairments to learning in all groups of patients, who had lesions in different sites, demonstrating that cortical mechanisms are involved in learning to control posture voluntarily. These studies showed that patients with lesions in the right hemisphere had rather greater deficits in performing the task than those with lesions in the left hemisphere. There were significant differences in the initial deficit in performing the task on the first day of training depending on the side of the lesion. All groups of patients differed from healthy subjects in that significant learning occurred only at the initial stages of training (the first five days). Learning at the initial stage in patients with concomitant lesions of the parietal-temporal area and with combined lesions with motor, premotor, and parietal-temporal involvement was significantly worse and the level of task performance at the end of the initial stage was significantly worse than in patient with local lesions of the motor cortex. The level of learning was independent of the severity of the motor deficit (paresis, spasticity), but was associated with the severity of impairment of the proprioceptive sense and the severity of disruption to the upright posture (asymmetry in the distribution of support pressures, amplitude of variation in the position of the center of pressures). The learning process had positive effects on the severity of motor impairment and on the asymmetry of the distribution of support pressures in the standing posture. Reorganization of posture during bodily movements occurred mainly because of impairment to the developed "non-use" stereotype of the paralyzed lower limb.

Biomechanical Phenomena↗
PubMedDate not supplied

[Deficit of learning of posture voluntary control in patients with cortical lesions of various locations: cortical mechanisms of posture regulation].

Forty two hemiparetic patients after cerebrovascular accidents were trained to change the position of the center of pressure according to a target on the screen with the visual feedback control. The learning was substantially impaired in comparison with the group of healthy subjects. Patients with the right-hemispheric lesions showed somewhat greater learning deficit than patients with lesions in the left hemisphere. Lesion localization also affected the process of learning. The learning was disturbed to a greater extent in patients with lesions involving not only motor but also premotor and parietal cortical areas. In patients with parieto-temporal lesions the learning reached a very low level after three initial days of training, possibly, because of the deficit of sensory integration and of body scheme in the extra-personal space. Patients with combined lesions of the motor, premotor, and parietal areas showed the lowest results. The learning was shown to depend on the deficit of proprioception and extent of postural disturbances (asymmetry of body weight distribution and amplitude of the center of pressure oscillations) rather than on the extent of motor deficit (paresis and spasticity). However, the learning itself improved some motor disturbances.

Biofeedback, Psychology↗
PubMedDate not supplied

[Use of a bilateral stabilographic platform in the diagnosis and rehabilitation of movement disorders at the clinic of nervous system diseases].

The paper presents the results of the study whose aims were to reveal the specific features of vertical posture maintenance in patients with various motor disorders by using a computer stabilographic complex with a bilateral platform, to draw up computer rehabilitative programmes that take into account the detected features of posture stability disorders in these groups of patients, to evaluate the efficiency of use of programmes drawn up to train vertical posture stability in the rehabilitation of patients with motor disorders of various origin.

Adult↗
PubMedDate not supplied

[Features of learning voluntary control of posture after pyramidal and nigrostriatal lesions].

The study was aimed at investigation of a deficit of learning the center-of-pressure voluntary control in patients with lesions of corticospinal and nigrostriatal systems. Thirty three patients with Parkinson's disease and 20 patients with hemiparesis after cerebrovascular accidents in the MCA participated in the investigation. The subjects stood on a force platform and in the form of a computer game were trained to match the projection of the center of pressure (a cursor) with a target on the screen under the visual feedback control. Two different postural tasks were presented. In the first task the direction of the center-of-pressure shift was not known before, so the subject learned the general strategy of the center-pressure control. In the other task a precise postural coordination should be formed. The voluntary control of the center-of-pressure position was found to be impaired in both groups of patients. In the task of moving the center of pressure in various directions (general strategy), no differences in the initial deficit of the task performance were found between the groups, but the learning was more efficient in the group of hemiparetic patients. However, in the task with precise postural coordination, despite the greater initial deficit in the parkinsonian patients, the learning in this group of patients was substantially more efficient than in hemiparetic patients. The results suggest both common and different features of the involvement of the corticospinal and nigrostriatal systems in learning voluntary control of posture.

Aged↗