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Biomedical subjects

V A Shabalov

Publications and source records attributed to V A Shabalov.

At least 19 recordsLinked to original sources
PubMed1996

[Use of neurotransplantation in the treatment of Parkinson's disease].

The outcomes of transplantation of the human embryonal mid-brain into the striatum of patients with Parkinson's disease are presented. For this, a procedure for obtaining, isolating, preparing the human embryonic midbrain, as well as a method for stereotactic administration of embryonal nerve tissue suspension having high dopaminergic neuron levels into the patients' striatum are specified. Patients underwent neurological examinations by the international protocol Core Assessment Program for Intracerebral Transplantation including monthly video recording within 3 months before and 3-24 months after surgery. Electrophysiological, neuropsychological, and immunological examinations were made at the same intervals. Most patients had positive dynamics: diminution of the severity of main disease symptoms, reduction in the efficiency of a single dose of DOPA-containing drugs, decrease in the magnitude of side effects of drug therapy.

Adult↗
PubMed1993

Functional neurosurgery using 3-D computer stereotactic atlas.

To facilitate a full-scale representation of thalamic nuclei and surrounding subcortical structures in the course of stereotactic procedures, a 3-D computer atlas of this region has been created, which permits visualization of the operative field including the involved structures and the position of the instrument. Necessary adaptation is performed according to the position of the intracranial reference points derived from CT-scan. Working with the atlas permitted more accurate and safer surgery. An IBM PC/AT computer was used.

Adult↗
PubMed1993

[The cerebrospinal fluid pathways in infantile cerebral palsy].

Liquor routes of the brain and spine were examined in 16 children aged 2 to 12 with infantile cerebral paralysis by radioisotope cistern-myelography with Tc99m-DTPK. Simultaneous imaging of liquor tract pathology in the brain and spine helped distinguish three variants of liquorodynamic abnormalities in infantile cerebral paralysis characterized by various combinations of disorders, in CSF circulation, resorption, and formation of routes for additional CSF discharge. The role of CSF routes involvement in the brain and spine in the formation of a pathologic pattern in infantile cerebral paralysis is analyzed.

Brain↗
PubMed1991

3-D computer model of subcortical structures of human brain.

Three-dimensional computer model of thalamus and adjacent formations of human brain has been elaborated on the basis of sagittal slices from the Schaltenbrand-Bailey stereotactic atlas. The model includes 120 morphologically distinguishable structures and consists of more than 16 million points (volume elements) each of them being associated with the particular structure in the brain. The model is stored in the long-term computer memory. A special software has been developed to facilitate utilizing the model obtained. The software facilitates synthesizing arbitrary cross-sections through the brain and provides the correspondence between the stereotactic coordinates of any point and its position on the screen of monitor. The coordinates of the point in the system of stereotactic atlas and the name of the structure, the point belongs to, are also supplied. It is also possible to get magnified images of cross-sections and to get isometrical images. The system enables the neurosurgeon to improve the planning and execution of stereotactic operations, and will also be helpful for education.

Brain↗
PubMed1990

[The neuronal reactions of the reticular nucleus of the human thalamus to verbal and sensory stimuli of differing signal strengths].

Responses of 340 single units of the n. Rt of the human thalamus to significant and insignificant verbal and sensory stimuli during the performance of voluntary motor acts recorded by microelectrodes were investigated in dyskinetic patients in the course of 46 stereotaxic operations. Two types of polymodal units with irregular continuous (A-type, "triggered verbal command" units, 183 neurons, 56% reacting) and burst rhythmic (2-5 per s.) discharges (B-type, 139 neurons, 59% reacting) have revealed reactivity to a verbal command with a specialized multicomponent pattern at functionally different stages of purposive motor acts. The analysis of principal components has shown that the extracted components of responses correlated with the functional significance of verbal or sensory signals, especially with voluntary acts of the verbal message triggering, but not with physical, somatotopic or semantic parameters of stimulation. It was suggested that the transient time-connectivity of A and B neurons at the trigger stages of purposive tasks reflected the coexistence in the Rt of two functionally different cellular subsystems participating in the transmission of significant signals during speech-provoked voluntary acts.

Acoustic Stimulation↗
PubMed1990

[The dynamic neuronal interactions in the reticular nucleus of the human thalamus to verbal stimuli of differing signal strengths].

Dynamics of neuronal interaction in 90 ensembles of the RT including units of two types (A, B) recorded by microelectrodes was analyzed during verbal and sensory stimulation and voluntary motor acts in dyskinetic patients in the course of 38 stereotaxic operations. It was shown that high transient interneuronal cooperation in A and B units were selectively related to triggering stages of a purposive act: verbal commands presentation and movement initiation and realization. Specific character of dynamics of interneuronal cooperation determined both by the type of constituent elements and functionally different stages of voluntary acts was found. It is supposed that transient interneuronal cooperation of A and B units reflects dynamic conjugation of two functionally different cellular subsystems in the Rt which are probably connected with verbal-related processing and triggering as well as with movement-related voluntary acts.

Acoustic Stimulation↗
PubMed1988

[Voluntary activity of the neck muscles in patients with spastic torticollis].

The authors investigated the characteristics of motor disorders in patients with spastic torticollis. The study involved registration of volitional tensions of the neck muscles in isometric conditions, i.e., when the patient's head was rigidly fixed with regard to the body. Using a tensometric dynamometer the following three moments of force were measured: one responsible for bending the head forward or backward; the second, for bending the head to the right or left shoulder; and the third, for turning the head round the longitudinal axis. The electrical activity of the neck muscles was recorded with the help of surface electrodes. It has been established that the development of volitional efforts by the neck muscles under isometric conditions is difficult or impossible if directed to the side where the patient's forcible turn of the head is directed.

Chronic Disease↗
PubMedDate not supplied

[The effect of selective dorsal rhizotomy on motor function in patients with infantile cerebral palsy].

The authors analyze the outcomes of surgical treatment in 15 CP patients with lower paraparesis who had been treated with selective dorsal rhizotomy at the L2-S2 level. All the patients were examined by neurological study, EMG, EEG, visual evoked potential (VEP) recording and motor reaction time estimation. Based on the findings, it is suggested that SPR lumbosacral spinal level may affect cerebral function. Some motor functional changes are associated with this impact. Possible mechanisms of these changes are discussed.

Adolescent↗
PubMedDate not supplied

[The use of chronic epidural electrostimulation of the spinal cord in children with spastic diplegia--a type of infantile cerebral palsy].

The authors' first experience with spinal cord stimulation (SCS) at the lumbar level in the treatment of cerebral palsies (CP) in children aged 3-11 years who had lower spastic paraparesis of varying severity is presented. Complex clinical and physiological studies of all 9 children were made before and after surgery (follow-ups lasting 6-12 months). Preliminary results have indicated that the most significant changes occur primarily in pathological postural tonic reflexes. SCS has virtually no effect on fixed limb deformities, which requires further orthopedic surgical correction. A medical care schedule for CP children affected predominantly with lower spastic paraparesis should include, among its first priorities, electrode implantation for SCS. Due to the specific rehabilitative dynamics of motor functions, SCS should be made to treat these children before the deformities in the lower extremity joints get fixed.

Adolescent↗
PubMedDate not supplied

[Experience in surgical treatment of patients with focal forms of temporal epilepsy].

Fifteen patients with focal lesions of temporal epilepsy were examined before and 6 months to 4 years after surgery. There were low-grade gliomas in 13 cases, muscle tissue heterotopy in 1 case, and medial temporal sclerosis in 1. Epileptogenic lesions were localized in the medial structures of the temporal lobe in 10 cases and in the lateral temporal regions in 5 cases. Comprehensive neurophysiological study, including intraoperative electrocorticography, was used to identify an epileptogenic zone (EZ). EZs were found in the medial structures on the affected side in all patients. Lesionectomies were performed in all cases. It was combined with medial resection in 12 cases (it was done in 10 patients until epileptic activity disappeared). Nine patients stopped having seizures after surgery. One patient had only auras. Improvements were slight in 5 patients. A relationship was found between the surgical outcomes and the site of a lesion and EZ. They authors conclude that complete recovery may occur in cases with medial locations of a lesion and EZ. The outcomes of surgery are much poorer in cases with the lateral sites of an lesion and in those with the medial site of EZ.

Brain↗
PubMedDate not supplied

[Motor responses in transcranial magnetic stimulation and somatosensory evoked potentials in patients with pain syndromes].

The main goal was to evaluate the motor and somatosensory systems by recording evoked motor responses (EMRs) during transcranial magnetic stimulation (TMS) and somatosensory evoked potentials (SEPs) in patients with neurogenic pain syndromes before and after implantation of the systems for chronic antipain epidural stimulation. Fifteen patients with neurogenic pain syndromes and a control group of 15 apparently healthy examinees were examined. The patients were found to have a significant reduction in the motor thresholds of EMRs during TMS and an increase in the amplitude of EMRs after implantations of the systems. There were no significant changes in the amplitude-time characteristics of short SEPs as compared to the healthy examinees and after implantation of the systems. Analysis of the amplitude-time characteristics of long SEPs in these patients revealed a significant increase in the amplitude of the component P250 as compared to the normal values and its decrease after implantation of the systems.

Evoked Potentials, Somatosensory↗
PubMedDate not supplied

[Neurotransplantation in the treatment of Parkinson disease: follow-up].

The paper presents the results of follow-up of 11 patients with Parkinson's disease (PD) after neurotransplantation (NT) of fetal brain dopaminergic suspension into the caudatus and putamen on one or two sides. All the patients were clinically assessed at least 3 months before and during a follow-up (for as long as 9 years) in accordance with the Core Assessment Program for Intracranial Transplantation (CAPIT) by a Russian group of the Network of European CNS Transplantation and Restoration (NECTAR) Programme by using the Unified Parkinson's Disease Rating Scale (URDRS). An analysis of clinical findings showed that: 1) there was a slight amelioration in bradykinesia, rigidity, and smaller dosage of L-DOPA; 2) tremor and drug-induced dyskinesia remained unchanged; 3) subsequently (till 9 years), the clinical effect slightly decreased in almost all patients with PD and in some of them the clinical status became worse than that prior to surgery; 4) repeated NT (2 cases) in the striatum contralaterally did not improved the situation; 5) only neurostimulation of subcortical structures improved clinical results. So we can conclude that NT alone cannot be beneficial and requires additional interventions at the subcortical level.

Adult↗
PubMedDate not supplied

[Chronic spinal cord electrostimulation in the management of neurogenic pain].

According to the data of epidemiological surveys made in Russia, the prevalence of chronic pain (without cancer diseases being kept in mind) accounts for less than 40% of the adult population and these figures tend to grow steadily. Despite a continuous increase in the potentialities of pharmacotherapy, physiotherapy, and psychotherapy, the efficiency of treatment in patients suffering from various pains has remained ineffective so far. Surgical treatments for pain include anatomic, destructive (neuroablation), and non-destructive (electrical stimulation and neuromodulation) operations. The purpose of the paper is to present the results of use of chronic spinal cord stimulation in 10 patients (6 males and 4 females) with severe drug-resistant pain. The patients' age was 32 to 74 years (mean 47.2 years). The duration of the pain syndrome before surgery averaged 6 years (3-13 years). The severity of pain and its influence on the quality of life were assessed, by using a modified 10-score visual analogue scale. The operation was performed in 2 steps. The step involved electrode implantation along the Tuochi needle under X-ray control. If there were positive postoperative results, the second stage was implantation of the subcutaneous part of the system for chronic stimulation. Positive (excellent and good) results were obtained in 9 of the patients, excellent results being in 5 patients. The follow-up averaged 18 months (6 to 28 months). The late postoperative positive result remained in 8 patients. Two patients were observed to have complications as displacement of an epidural electrode, which required surgical correction of its position. Resurgery restored the antipain effect of stimulation. Chronic epidural stimulation can be the method of choice in treating neurogenic pain since it is minimally invasive and more effective than other surgical treatments.

Adult↗
PubMedDate not supplied

[The genesis of movement-related human brain potentials in different forms of motor pathology].

To study the role of subcortical structures and cerebellum nuclei in the genesis of the human brain potentials connected with motion patients were examined with parkinsonism and hyperkinetic form of children cerebral paralysis. In one group of patients the motor responses were recorded by means of long-term electrodes implanted with the medical purpose into the ventro-oral group of thalamus nuclei, subcortical nuclei and dentate cerebellum nuclei. In patients of the second group potentials, connected with motion were led from the scalp before and after one-moment destruction in the zone of the same structures. In ventro-oral and reticular thalamus nuclei lateral and medial segments of the pale globe and in the cerebellum dentate nucleus post-motor components were recorded which were considered as electrographic expression of motion realization and completion processes (P2 and N3) and also as slow negative oscillation (component N1), that pointed to participation of the studied structures not only in regulation of voluntary movement but also in the process of movement preparation. Absence of N2 component at recording motor responses from deep electrodes and its sufficient stability at scalp leads gave the reason to suggest that its genesis was connected with the cortex activity.

Action Potentials↗