Until recently, no classification of epileptic syndromes officially approved by the International League Against Epilepsy (ILAE) was available. In 2022, owing to many year-persistent efforts made by experts and the public community, the studies providing the definition and classification of epileptic syndromes were published. ILAE has approved the following definition of the epileptic syndrome: “a characteristic cluster of clinical and EEG features, often supported by specific etiological findings (structural, genetic, metabolic, immune, and infectious)”. The classification of epileptic syndromes is proposed according to the age principle: onset in neonates and infants, onset in childhood, onset at a variable age. Separately, the syndromes of idiopathic generalized epilepsy were presented. Clinical data for each epileptic syndrome are presented in a single pattern: epidemiology, clinical context, natural history, type(s) of seizures, electroencephalography, neuroimaging findings, genetic findings, other laboratory findings (when informative), differential diagnosis. The criteria for diagnosis, including mandatory criteria, warning signs and exclusion criteria, are given. This classification should be a starting point for further improvement in the organizing work of practitioners who deal with epilepsy.

Background. Surgical treatment has shown its effectiveness for patients with drug-resistant focal epilepsy: resection or disconnection of the epileptogenic zone leads to relief from epileptic seizures. However, in some cases non-invasive examination may not be sufficient for localization of epileptogenic zone boundaries. Hence, such patients undergo invasive encephalography (EEG) to clarify zone location accounting for seizure development.

Objective: to evaluate effectiveness of invasive stereo-EEG in the diagnostics of drug-resistant focal epilepsy.

Material and methods. The data collected from 65 patients who underwent stereo-EEG during pre-surgical examination for pharmacoresistant focal epilepsy were retrospectively analyzed within the period of 2016–2019. According to the results of magnetic resonance imaging (MRI), 34 patients had MRI-negative forms of epilepsy, and 31 patients had MRI-positive forms with multiple structural changes in the brain or discrepancies between electro-clinical data and MRI findings.

Results. Based on the information obtained by stereo-EEG, 49 patients (75.4%) underwent resection operations. In 16 (24.6%) cases surgical treatment was not carried out due to detected bilateral epileptogenic zone, the lack of convincing data on its location or detecting an epileptogenic zone in a functionally significant region. In 44 operated patients, the follow-up comprised more than 12 months; it was not possible to contact 5 patients. Engel outcomes: I class – 27 (61.3%) patients, II class – 7 (15.9%), III class – 4 (9.1%), IV class – 6 (13.6%). As a result of stereo-EEG, hemorrhagic complications developed in 2 (3.1%) patients: epidural hematoma in 1 case (1.5%), and intracerebral hematoma in 1 case (1.5%). No persistent neurological deficit was noted during continued monitoring.

Conclusion. The method of stereo-EEG is effective for determining the epileptogenic zone boundaries in patients with drug- resistant focal epilepsy.

Objective: analysis of treatment tactics for patients with magnetic-resonance-imaging (MRI) negative epilepsy, characteristics of morphological data and assessment of the treatment results.

Material and methods. Within the period of 2013–2021, 31 patients under the age of 18 with drug-resistant nonlesional epilepsy were examined according to the “epilepsy” MRI-protocol. Patient distribution by gender, age, duration of illness, age of onset, number of anticonvulsant protocols, frequency of seizures at the time of initiated treatment, side and lobe of the seizure generation zone was analyzed. The instrumental diagnostic methods were noted in a specially designed study form and reported contribution of relevant result to epileptogenic zone. The distribution of patients according to surgical intervention and histological data was also analyzed.

Results. Resection surgery was carried out in 26 (83.9%) patients. Palliative operations were performed in 5 (16.1%) cases with bilateral localization of the epileptic focus: callosotomy (3) and vagal nerve stimulation (2). Twelve months post-therapy outcomes by Engel class I were found in 19 (61.3%) patients, class II – in 6 (19.4%), class III – in 5 (16.1%), and class IV – in 1 (3.2%). Long-term results of surgical treatment were assessed 3 and 5 years later.

Conclusion. Surgery of MRI-negative epilepsy can be effective with seizure-free outcome in 61.3% of cases, but requires use of additional diagnostic methods in relation to standard pre-surgery examination to localize epileptogenic zone.

Background. Epileptic seizures represent one of the leading clinical manifestations of glial brain tumors that develop on average in 51% of cases. In gliomas, epileptogenesis is quite complex and multifactorial.

Objective: to study a role of the expressed glutamine synthetase enzyme, as well as cystine/glutamate transporter (xCT system, SLC7A11) in the pathogenesis of epilepsy developing in patients with cerebral gliomas.

Material and methods. The study included 32 patients with supratentorial gliomas. The average age of the disease onset (diagnosis) was 50.69±18.01 years. All patients underwent inpatient examination and treatment at the Neurosurgery and Nervous Diseases Clinics of Kirov Military Medical Academy from 2018 to 2020. In all cases, a biopsy of tumor tissue was collected. Histological and immunohistochemical studies were performed (expression of glutamine synthetase and cystine/ glutamate transporter (SLC7A11, xCT)).

Results. Significant (ANOVA p=0.027, Mann–Whitney U-test p=0.033) differences in the expression of cystine/glutamate transporter (xCT system, SLC7A11) were revealed, by showing the following median values (lower quartile; upper quartile): 50% (45; 75) in the group of patients with seizures, 40% (40; 50) in the seizure-free group. The expression level of glutamine synthetase did not significantly differ in the groups with and without seizures.

Conclusion. The data obtained confirmed that one of the pathogenetic mechanisms for epilepsy development in patients with gliomas was related to highly expressed cystine/glutamate transporter (xCT system, SLC7A11) and, as a consequence, an increase in the extracellular glutamate level.

The clinical case of a patient with congenital contractures of the lower and upper limbs, face, seizures, facial dysmorphias, motor disorders and psychomotor development delay is presented. The proband with Freeman–Sheldon syndrome had no mutations in genes associated with distal arthrogryposis. Chromosomal microarray analysis revealed terminal duplication of the long arm of chromosome 9 and terminal microdeletions of the short arm of chromosome 20 – 46,XX.arr[hg38]9q33.3q34.3 (127016168_138124666) x3,20p13 (259113_1003183)x1 in the de novo status. This clinical observation demonstrates an opportunity of using innovative molecular cytogenetic technologies in the search for disease-related genetic causes in the absence of mutations detected by whole exome sequencing.