Introduction. Drug-induced dyskinesia is an iatrogenic undesirable side reaction from the extrapyramidal system that occurs during the administration of drugs, most often antipsychotics in patients with schizophrenia. At the end of the 20 th century, studies were conducted on the search for candidate genes and the carriage of single nucleotide variants of antipsychotics-induced tardive dyskinesia.
Purpose of the study – to analyze research results reflecting candidate genes and their single nucleotide variants associated with antipsychotic-induced tardive dyskinesia.
Materials and methods. We searched for full-text publications in Russian and English in the eLIBRARY, PubMed, Web of Science, Springer databases using keywords (tardive dyskinesia, drug-induced tardive dyskinesia, antipsychotics, antipsychotics, typical antipsychotics, atypical antipsychotics, genes, polymorphisms) and combined searches for words over the past decade.
Results. The lecture discusses candidate genes encoding proteins/enzymes involved in the pharmacodynamics and pharmacokinetics of antipsychotics
Conclusion. Timely identification of individual genetic characteristics of the patient can contribute to the development of diagnostic test systems and in the future selection of the safest and most effective antipsychotic therapy.

Cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS) is a relatively poorly understood autosomal recessive neurodegenerative disease. The molecular basis of CANVAS was discovered only in 2019 and it is associated with the biallelic pentanucleotide AAGGG expansion carriage in the RFC1 gene. With the advent of genetic diagnostics, the understanding of the phenotypic spectrum and variety of clinical manifestations of this disease has expanded, including a combination of cerebellar ataxia and sensory neuropathy, as well as isolated sensory polyneuropathy/ganglionopathy. This review details current information on the etiology, pathogenesis, clinical presentation and diagnosis of CANVAS in order to increase the awareness of practitioners and early diagnosis of this disease.

Introduction. Spinal muscular atrophy is a severe neuromuscular disease characterized by rapid progression of muscle weakness and early death. Pathogenetic therapy with nusinersen can significantly change the course of the disease and enable the patient to acquire new skills. The study of the efficacy and safety of nusinersen therapy in patients with type 1 spinal muscular atrophy should be continued.
The aim of the study was to assess the safety and efficacy of nusinersen therapy in patients with type 1 spinal muscular atrophy for 6 months as part of an expanded access program at federal and regional healthcare facilities.
Materials and methods. Patients with type 1 spinal muscular atrophy received nusinersen therapy under the expanded access program (NCT02865109). Patients were evaluated before starting treatment and 6 months after starting treatment. Overall motor development and motor function was assessed using the Hammersmith Infant Neurological Status Scale Part 2 and the Philadelphia Pediatric Hospital Neonatal Motor Scale.
Results. 41 children aged 6 to 38 months received nusinersen therapy between July 2019 and March 2020. At the time of analysis, all patients were alive and continued treatment. The average improvement on the Hammersmith Hospital Neurological Status Scale was 3.7 points after 6 months of therapy compared to baseline (n = 39, p <0.001). The mean improvement on the Children’s Hospital of Philadelphia Scale for the Diagnosis of Motor Function in Newborns was 9.8 after 6 months of therapy from baseline (n = 30, p <0.001).
Conclusion. The efficacy and safety of nusinersen have been demonstrated in real clinical practice in Russia in the treatment of early-onset spinal muscular atrophy.

Introduction. Transcranial electrical stimulation is a neurophysiological method that is used intraoperatively for evaluating the conduct of a nerve impulse through the cortical-spinal tract. However, the results obtained during registration of this modality do not always correlate with the neurological status of the patient after surgery.
The purpose of the study is to determine the prognostic significance of motor evoked potentials in surgical interventions for the elimination of spinal stenosis at the cervical level.
Materials and methods. The study analyzed the results of 20 microsurgical root decompressions at the cervical level by eliminating spinal stenosis. Surgical interventions were performed in the neurosurgical Department of National medical and surgical center named after N.I. Pirogov from august 2018 to march 2019. Intraoperatively there were used the following modalities: motor evoked potentials, 3-channel registration of somatosensory evoked potentials from the median nerves, 8-channel electroencephalography, and train-of-four monitoring. The patients were divided into 2 groups: in the 1st group was used inhalant anesthetics, in the 2nd the anesthesia was conducted according to the protocol “Total intravenous anesthesia”.
Results. Within each group, in a number of cases, there was a decrease in the response amplitude (by 80 % or more), as well as a loss of motor evoked potentials. In the “Total intravenous anesthesia” group, the current stimulation forces used to obtain motor evoked potentials did not exceed 150 mA, while in the group of inhaled anesthetics, the maximum value was 300 mA, and the average value was 170 mA. In the “Total intravenous anesthesia” group, in 2 cases, a loss of response from one myotome at the decompression phase was registered without recovery during intraoperation monitoring, in 2 cases there was the amplitude loss by 80 % or more with subsequent recovery. In the “Total intravenous anesthesia” group, the results were comparable.
Conclusion. During neurophysiological monitoring in surgeries at the cervical level, the loss of motor evoked potentials from one myotome, as well as a decrease the response amplitude by 80 % or more are doubtful as a criteria for predicting neurological deficit.

Background. Nitrous oxide abuse (“laughing gas”, N₂O) is common among young people attending nightclubs. Contrary to popular belief about the safety of N₂O, in some cases neurological complications develop due to a deficiency of vitamin B₁₂, the activity of which is blocked by N₂O.
Purpose of the study – to determine the typology and course of neurological disorders in a group of patients who regularly use “laughing gas”. To note the key diagnostic markers that allow verification of vitamin B₁₂ deficiency induced by nitrous oxide consumption. To describe pathogenetic therapy features and follow-up.
Materials and methods. The study included 12 patients (10 men and 2 women) aged 18 to 45 years (average age 29 years) with a diagnosis of B₁₂-deficient myelopolyneuropathy induced by regular use of nitrous oxide.
Results. The most common neurological complication of nitrous oxide abuse for more than 1 month was a generalized lesion of the peripheral nerves with acute or subacute distal symmetric sensory or sensorimotor axonal polyneuropathy. In the clinical picture, sensory complaints and disorders prevailed. Paresis developed in half of the cases. A typical neuroimaging symptom characteristic of funicular myelosis was rarely detected (16.7 %). A decrease in B₁₂ vitamin level could most reliably be diagnosed only indirectly, by the presence of hyperhomocysteinemia (91.7 % of cases). In all cases that were followed-up, prolonged therapy with cyanocobalamin led to partial (n = 5; 62.5 %) or complete (n = 3; 37.5 %) regression of neurological symptoms.
Conclusion. Caution regarding the use of nitrous oxide should be in all cases of predominantly sensory polyneuropathy with acute or subacute development in young and middle-aged people. A thorough history taking (targeted survey on the fact of nitrous oxide consumption) and diagnostics (testing the level of homocysteine, if possible methylmalonic acid) allow you to not miss a deficiency of vitamin B₁₂, the treatment of the consequences of which with timely verification and adequate correction is quite effective. It is recommended that the level of homocysteine in the blood to be regularly monitored during the treatment (in order to achieve its normalization).

Introduction. Over the past several decades, the study of mutations associated with motor neuron disease has led to the development of a number of transgenic animal models of motor neuron disease. One of the causes of the familial form of this disorder is mutations in the gene encoding Cu/Zn superoxide dismutase 1. The B6SJL-Tg (SOD1*G93A) mouse strain expresses a mutant form of human superoxide dismutase 1.
Aim of study. To assess motor functions, dynamics of survival, and morphological changes in the spinal cord of transgenic B6SJL-Tg (SOD1*G93A) mice.
Material and methods. In total, 31 animals have been studied. Starting from the age of 22 weeks, once every two weeks, the “open field” and “beam walking” motor tests were performed. The morphological changes in the spinal cord were evaluated at intermediate (26–35 weeks) and late stages (40–45 weeks). Neuronal proteins NeuN and PGP9.5, gliofibrillar protein, cyclonucleotide phosphatase (a marker of oligodendroglia) and a marker protein of microglia IBA1 were detected by immunohistochemistry; antibodies MTC02 to the outer membrane protein were used to detect mitochondria.
Results. Motor problems appeared at the age of 24–26 weeks and steadily progressed; one could see consistent paresis of the hindlimbs, then the forelimbs, which was accompanied by general hypotrophy of the animals. There was a greater variability in the timing of symptom onset and life expectancy in males compared to females. The neurodegenerative process with damage to motor neurons was accompanied by the activation of micro- and astroglia. A sharp decrease in immunoreactivity to the mitochondrial marker MTC02 was found.
Conclusion. The obtained results demonstrate new details of the development of a complex of motor and pathomorphological changes characteristic of motor neuron disease in B6SJL-Tg (SOD1*G93A) mice. Clarification of the fine dynamics of the neurodegenerative process in these animals is of great importance for monitoring the course of the disease during preclinical trials of new drugs and methods of gene therapy.

The article describes the clinical and genetic characteristics of 2 patients from Russia with autosomal recessive primary microcephaly type 2, caused by previously described and newly identified mutations in the WDR62 gene. The data obtained the support the hypothesis that there are no clear correlations between the type and location of the mutation and the severity of clinical manifestations of the disease. There is discussed the possible influence of a mutation in the WDR62 gene on the occurrence of a fibrillar astrocytoma.