Pharmacoresistant temporal epilepsy: the relationship of epileptiform activity and structural changes in the hippocampus

Background. Hippocampal sclerosis is one of the most common structural lesions associated with epilepsy. The standard medical care in the treatment of drug-resistant temporal lobe epilepsy associated with hippocampal sclerosis is surgery with anterior temporal lobectomy. The extent of resection depends on the involvement of hippocampal sclerosis in the epileptic system. Objective. Determine the relationship between the involvement of the hippocampus in the epileptic system (on the basis of the results of intraoperative electrocorticography (ECoG)) and the presence of structural changes in it, found on the basis of MRI data. Materials and methods. The present article presents an original retrospective study of the dependence of the signs of hippocampal sclerosis according to neuroimaging data and the formation of epileptiform activity in 36 patients treated at the Polenov Neurosurgical Institute — branch of Almazov National Medical Research Centre in 2015–2018. Results. Depending on the presence of hippocampal sclerosis and epileptiform activity, patients were divided into 4 groups: 1) patients with the presence of both hippocampal sclerosis and epileptiform activity in the mesiobasal structures (n = 15); 2) patients with identified sclerosis of the hippocampus, without registration of specific activity according to the results of ECoG (n = 8); 3) patients with epileptiform activity, while MR-negative (n = 10); 4) patients without epileptiform activity and without signs of hippocampal sclerosis according to MRI (n = 3). After a statistical check of the distribution of patients, it was found that the distribution was random. Conclusion. The fact of the presence of structural changes in the hippocampus could not be a pathognomonic sign of the inclusion of the hippocampal-entorial complex in the epileptic system.

Effect of lacosamide on epileptiform activity and structure-function relations in the brain of rats with chronic focal epilepsy

The aim was to study the effect of lacosamide on epileptiform activity (EрA) and structure-function relations in the brain in the course of development of the epileptic system in rats with cobalt-induced chronic epilepsy. Materials and methods. To model chronic focal epilepsy, we used topical applications of cobalt on the sensorimotor zone of the rat cortex. The effect of lacosamide (20 mg/kg) on the cobalt-induced epileptiform activity was analyzed in parallel with with the monitoring of spectral-coherent changes in the brain during the development of the epileptic system (ES). Results. In the first 30 minutes after the administration, lacosamide briefly enhanced the EрA in the hippocampus and ipsilateral cortex, and also strengthened the cortical-hippocampal (at stage 1) and cortical-hypothalamic connections (at stage 2). Two hours after the drug administration, a decrease in EрA was observed at stages 1 and 2 of the ES development, especially in the contralateral cortex and hippocampus. At all frequency ranges, the level of the inter-center connections decreased (most pronounced in the cortical-hippocampal links). Conclusion. The effect of lacosamide on EрA in the rat brain with cobalt-induced epileptogenic focus is characterized by a decrease in EрA, two hours after the drug administration. This effect is most expressed in the cortex and hippocampus, and is accompanied by a decrease in the level of the corticalhippocampal connections.

Eeg-analysis of the effect of combined use of carbamazepin and mexidolum on the epileptiform brain activity

Experiments on rats with chronic epileptogenic fod in sensomotor region of cortex showed that effects of anticonvulsive agents depend on the progression phase of epileptic system. Effect of carbamasepinum in effective doses is mostly expressed during the phase of stable epileptic system with determinant foci in limbico-hypothalamic structures. Lowering the doses of the drug brings about a decrease of anticonvulsive effect and activation of the secondary hippocampal focus. Combined use of carbamazepin and mexidolum with membra-notropic antioxidantal activity bbrings about an increase of anticonvulsive properties of carbamazepin and allows to decrease the therapeutic doses of the last.