[Clinical and electromyography characteristics of chemotherapy-induced polyneuropathy]. / Klinicheskie i élektroneiromiograficheskie osobennosti postkhimioterapevticheskoi polineiropatii.

AIM: The study aimed at determining clinical and electromyography characteristics and developing the methods of CIPN treatment. MATERIAL AND METHODS: A clinical and electromyographic examinations and treatment of 30 with CIPN symptoms developed after polychemotherapy were performed. The authors developed treatment schemes included allopathic, homeopathic drugs, hydrotherapy and pharmacopuncture. RESULTS AND CONCLUSION: Most of the patients were diagnosed with axonal polyneuropathy with affection of long nerves of the limbs, some patients had a combination of axonopathy with myelopathy. After treatment, regression of neuropathy symptoms and improvement of quality of life was noted in all patients.

[Aspects of encephalopathy in oncologic patients after chemotherapy].

OBJECTIVE: To study clinical presentations and neuroimaging results in post chemotherapy encephalopathy. MATERIAL AND METHODS: We examined 27 patients with cancer after chemotherapy (n=16) or chemoradiation (n=11). RESULTS AND CONCLUSION: All patients complained of memory impairment, sluggish mentality, moderate headache, fatigue, sleep disorder, irritability. Their neurologic status included different organic symptoms. Post chemotherapy encephalopathy is characterized by the combination of severe cerebral asthenia and different organic neurologic symptoms with moderate cephalgic syndrome. MRT showed single and multiple loci of gliosis in the white matter.

[Clinical characteristics and treatment of polyneuropathy developed after chemotherapy].

Chemotherapy-induced peripheral neuropathy (CIPN) is one of the main problem of modern cytotoxic therapy. Drug dose reduction, delay or even complete stopping of chemotherapy until the regression of CIPN symptoms impair treatment effectiveness and patients' survival. We studied 44 cancer patients with CIPN developed after polychemotherapy. We suggested a treatment regimen that included a complex of allopathic, homeopathic drugs and hydrotherapy. The treatment resulted in a subjective and objective regression of neuropathy symptoms and improving of quality of life in all patients. Patients who had to delay chemotherapy were able to restart it.

[Higher mental functions and cognitive auditory event-related potentials impairment in liquidators of Chernobyl accident].

An integrated neuropsychological study and analysis of cognitive auditory event-related potentials (ERP) using the three-stimulus oddball paradigm was performed in ten subjects who participated in the liquidation of Chernobyl accident and ten healthy subjects. Impairment of higher mental functions, including aspontaneity, fatigability, a decrease in the auditory-verbal and visual memories, and higher motor function deficiency was shown in liquidators. A decrease of amplitude in all components of ERP (N1, N2 and P3) was found in liquidators for all stimuli in both experimental situations (audition of all stimuli and counting of deviant stimuli) compared to healthy subjects. The latent period (LP) of ERP in liquidators was decreased for N1 and N2 components and increased for P3. The largest between-group differences in the LP were revealed in the frontal areas for N1 and P3 in the left hemisphere and for N2 - in the right one. The correlation analysis between the ERP and a neuropsychological study had shown that changes in the LP of N1 are correlated to the impairment of short-term memory and pose praxis of the right hand while changes in the N2 were correlated to the impairment of long-term memory and pose praxis of the left hand. The changes in LP of P3 were correlated to complex cognitive processing disorders. Thus, the complex study identified the deceleration of perception, processing, and analysis of information combined with the weakened inhibition and "uneconomical" type of reactivity which led to the impairment of higher mental functions in liquidators compared to healthy subjects of the same age. The changes found in liquidators are similar to those observed in elderly people and support the hypotheses on accelerated brain ageing caused by low dose irradiation.

[Specificity of auditory evoked potencials changes in participants of Chernobyl accident consequences: I. Analysis of early N1 component].

Amplitude-time characteristics analysis of the N1 component of auditory cognitive evoked potentials (EP) was made in 10 persons who had participated in the cleanup of the Chenobyl Accident - liquidators (mean age 50.5 +/- 4.0 years old) and in 10 healthy subjects (mean age 47 +/- 6.0 years old). Comparison of amplitude features of the N1 auditory EP component in liquidators of the Chernobyl Accident found a decrease in all areas of the cortex with the maximum decrease in the central and frontal leads, and also an inversion in reactive changes to stimuli of different significance in comparison to healthy subjects of the same age. The most distinct differences between the healthy subjects and liquidators of the Chernobyl Accident were found for time characteristics of the N1 component. They show a significantly smaller value of latent period (LP) for all stimuli and for all experimental tasks in comparison with healthy subjects and more distinct for a significant stimulus when persons counted these stimuli. Analysis of regional changes in LP of the N1 component found that liquidators, in comparison with healthy subjects, have maximal differences in the frontal area of the left hemisphere which were accompanied with inversion asymmetry of LP in this component. Less distinct changes were observed in the central area with relatively little damage in the parietal area. Detected changes in the amplitude-time characteristics of the N1 component of the auditory cognitive EP in liquidators of Chernobyl Accident can show an abnormality in primary attention and its reserves due to weakened inhibitory processes in comparison with healthy subjects, which has similarities of old age. The obtained data supports the hypothesis about the accelerated brain aging in liquidators of Chernobyl Accident as a result of low dosage radiation effects; however, it also allows the pathological development of the brain ageing due to the effects of radiation.

[Premature aging of an organism and characteristics of its manifestation in remote period after low dose irradiation].

In this study 58 participants of the liquidation of the consequences of Chernobyl accident in 1986-1987 were investigated. All the patients complain of constant headaches, disorders of memory, general weakness, rapid fatigability, decreased sexual drive, emotional instability etc. The complex (comprehensive) modern methods of investigation were used to carry out the objective assessment of presented complains and of character of the central nervous system damage: complex computer quantitative analysis of mental capacity; analysis of personality traits by using the MMPI test; single photon emission tomography (with the drug of Ceretec); X-ray computer tomography; magnetic resonance computer tomography. The experimental study with examination of primates who were exposured in sum dose 1 Gy (by drop method) was carried out, too. The results of complex investigation of participants of liquidation of Chernobyl accident consequences enable to postulate the formation of premature aging of an organism in these persons. Data of the experimental study of primates irradiated in dose 1 Gy revealed formation of the brain atrophy in the remote period after low dose radiation exposure.

[Impairment of space-frequency parameters of EEG coherence during cognitive performance (consequences of Chernobyl accident)].

Changes in frequency and space parameters of the EEG coherence evoked by cognitive performance were analyzed in 13 healthy subjects and participants of the Chemobyl clean-up. In healthy subjects, the EEG coherences in the alpha and beta frequency bands were significantly increased during arithmetic count and during visuospatial performance. Each test was characterized by regionally-specific features. Chemobyl patients demonstrated a global decrease in the EEG coherence predominantly in the alpha and beta frequency bands, especially in the frontal cortical areas. Patients with various pathological EEG patterns demonstrated specific impairment of EEG parameters. In patients with a "flat" EEG pattern, the EEG coherence predominantly decreased in the frontal associative areas, especially during arithmetic calculation. In patients with a "hypersynchronous" EEG pattern, the decrease in the EEG coherence was most pronounced in the parietal associative areas, especially during the visuospatial performance. The revealed impairments of the EEG coherence reactivity may be a reflection of disorders of the intracortical and corticosubcortical interaction and can result from the remote postradiation brain atrophy, especially, of cortical structures.

[Post-radiation effect on the interhemispheric asymmetry in EEG and thermography characteristics]. / Postradiatsionnye narusheniia mezhpolusharnoi asimmetrii élektroéntsefalograficheskikh i termograficheskikh kharakteristik vo vremia kognitivnoi deiatel'nosti.

Complex analysis of EEG and thermographic parameters carried out in 10 healthy subjects and 34 patients, Chernobyl clean-up participants revealed a correlation between EEG and brain temperature changes in the baseline state and during mental arithmetic. During cognitive activity the maximal increase in the average EEG coherence and temperature shifts in healthy subjects were observed in the left frontotemporal and right parietotemporal areas. In patients changes in both parameters under study were most pronounced, the interhemispheric relations were impaired. The visual analysis revealed "flat" and "hypersynchronous" EEG types in patients. The dominant pathologic activity in the betal range indicative of mediobasal and oral brainstem lesions was characteristic of the flat EEG. This type of activity was observed in 60% of patients. In these cases, a general decrease in EEG coherence and temperature was most pronounced in the left hemisphere. The hypersynchronou EEG type (40% patients) was characterized by paroxysmal activity in the theta and alpha ranges suggesting diencephalic brain lesions. In these cases, EEG coherence and temperature were more variable; changes in the right hemisphere were significant, be it increase or decrease. Our complex approach to investigation of brain activity in different aspects seems to be promising in estimation of the brain functional state both in healthy persons and patients in remote terms after exposure to radiation. The specific hemispheric temperature changes revealed in Chernobyl patients especially during cognitive activity can be the sequels of postradiation disorders of vascular neuro-circulation. The EEG findings suggest subcortical disorders at different levels (diencephalic or brainstem) and functional failure of the right or left hemispheres in remote terms after exposure to radiation.

[Postradiation changes in the brain asymmetry and higher mental functions of right- and left-handed subjects (the sequelae of the accident at the Chernobyl Atomic Electric Power Station)]. / Postradiatsionnye izmeneniia asimmetrii mozga i vysshikh psikhicheskikh funktsii prevshei i levshei (posledstviia avarii na Chernobyl'skoi AES).

The present study was aimed at comparative electrophysiological, clinical, and neurophysiological assessment of the brain functional state in dextrals (50 men) and sinistrals (5 men), who participated in the Chernobyl clean. The patients were observed over the course of 10 years (from 1990 to 1999). The results of examination of healthy persons (20 dextrals and 10 sinistrals) were used as a control. The clinical examination revealed the earlier manifestation and more severe development of paroxysmal and epileptic seizures in sinistrals than in dextrals. Electrophysiological study showed a progressive decrease in interhemispheric asymmetry of the EEG coherence characteristic for a healthy brain to inversion of its sign. These changes were more pronounced in sinistrals. In the remote terms after radiation, the interhemispheric EEG coherence decreased over the whole cortex, especially, in the frontal and central areas in both groups of patients. Neurophysiological study revealed a progressive impairment of voluntary motor activity and tactile sensibility, especially, in the left hand. These defects were more expressed in sinistrals than in dextrals. The results of complex and longitudinal examination suggest that the observed changes in brain asymmetry and interhemispheric interaction can be not only a result of a dysfunction of subcortical limbic-reticular and mediobasal brain structures but also a result of the white matter damage including corpus callosum. More expressed impairments in sinistrals than in dextrals can be explained by specific morphofunctional organization of the brain in persons with different sensor and motor asymmetries.

[A dynamic assessment of the reaction of the human brain to radiation exposure (the aftermath of the accident at the Chernobyl Atomic Electric Power Station)]. / Dinamicheskaia otsenka reaktsii mozga cheloveka na vozdeistvie radiatsii (posledstviia avarii na Chernobyl'skoi AES).

The present study was aimed at the comparative assessment of electrophysiological and clinical data in persons (155 right-handed men) who took part in the Chernobyl clean-up in different periods after radiation. Dynamic evaluation of psychoneurological disorders revealed the growth of incidence and severity of cerebrovascular disturbances accompanied by the signs of organic symptoms' aggravation and encephalopathy in longer periods after radiation. The results of neuropsychological examination also showed the deterioration of patients' state manifested as growth of fatigue, cognitive defects, and emotional impairments. Analysis of the EEG parameters, including power and coherence mapping and 3-d dipole source localization analysis demonstrated the increasing number of patients with the most severe forms of EEG pathology: the "plane" type in combination with fast paroxysmal (beta-band) and slow forms of activity from 45% in 1990-92 to 63% in 1997. The "hypersynchronization" type of EEG activity was typical for the earlier period accompanied by the dominance of the pathological forms of EEG activity in mediobasal structures of the left hemisphere, and brainstem zones vs. diencephalon and the right hemisphere. The later period was characterized by decreasing coherence in symmetrical frontal and front-temporal areas of the left hemisphere, while in the early period the hypersynchronization prevailed in symmetrical central areas and in the right hemisphere. The evidence were obtained to a disconnection between the brain hemispheres. We suppose that the progressive involvement of structures of the limbic-reticular complex (especially, brainstem, mediobasal structures, and white matter) into the pathological process occurs with time in participants of clean-up of the Chernobyl disaster consequences.

[The characteristics of the late reaction of the human brain to radiation exposure: the EEG and neuropsychological study (the sequelae of the accident at the Chernobyl Atomic Electric Power Station)]. / Osobennosti otdalennoi reaktsii mozga cheloveka na vozdeistvie radiatsii: EEG i neiropsikhologicheskoe issledovanie (posledstviia avarii na Chernobyl'skoi AES).

We examined 23 patients (participants in the clean-up of the consequences of the Chernobyl accident in 1986-1987) using neuropsychological and electrophysiological approaches. The results obtained by means of EEG coherence analysis, three-dimensional source localization, and dichotic listening test were compared. All the patients showed some common dysfunctions such as disturbances of hemispheric interaction which resulted in deterioration of the brain functional state in comparison with the control group. Neuropsychological evidence and source localization of the epileptiform EEG suggested predominantly subcortical damage at the limbic-reticular and, especially, diencephalic level. The observed signs of the left-hemispheric dysfunction depended on the brainstem damage while the right-hemispheric dysfunction were explained by the diencephalic damage. The observed symptoms were considered as a result of subcortical brain lesions at different levels rather than the primary cortical hemispheric damage.

[The late sequelae of radiation exposure on the nervous system]. / Otdalennye posledstviia luchevogo vozdeistviia na nervnuiu sistemu.

Clinical, neuropsychologic, neurophysiologic as well as neuromorphologic (in legal cases) examinations of Chernobyl liquidators were performed. In addition, the study was made of the monkeys exposed to 1,5 Gy radiation. The results obtained testified to the organic character of cerebral damages. They may be characterised as chronic progressive discirculatory-hypoxic syndrome in which disorders of vascular permeability were expressed and dystrophic destructive irreversible alterations of nervous cells occurred.