[Morphologic characteristics of cortical synapses in patients with epilepsy].

Ultrastructural examination of 70 human cerebral cortex specimens was carried out. The material was obtained during operations for brain tumours in patients with or without epileptic attacks and during stereotaxic biopsy for unexplained epilepsy (E). Morphometric techniques were employed in the study.

[Morphology of the epileptic neuron].

Using electron microscopy, the authors studied neurons and their synapses in the cortical foci of the brain in patients (1) with brain tumours attended by epileptic seizures, (2) with tumours accompanied by no paroxysms, and (3) with epilepsy of unknown etiology. The material was obtained in the interparoxysmal period. Morphometric study of the ultrastructure showed that morphological changes characteristic of epileptization were determined only in axodendritic (AD) and axospinal synapses in the form of their massive activation whose degree was calculated by collating the area of the "active zones" with the area of the entire synaptic surface.

[Morphogenesis of epileptic seizures].

As a result of micro- and ultrastructural examinations of the epileptic foci in patients with epilepsy the authors have demonstrated a phasic character of the morphogenesis of the epileptic seizures. The first phase was the formation of the pathological focus (appearance of respective histo- and ultrastructural changes in the neurons, glia, and vessels) without seizures. The second phase was characterized by epileptization of the neurons: this manifested itself in mass activation of the axo-dendritic synapses (formation of the primary epileptic focus).

[Ultrastructural bases of neuron "epileptization" and brain "convulsive readiness"].

Ultrastructure of the neurons of an epileptic focus in patients with cerebral tumors accompanied by epilepsy (group 1--40 observations) and the cortex adjacent to the tumor without epilepsy (group 2--20 observations) was studied. The results of electron microscopic examinations of these cases were compared. Ultrastructural changes of the neurons in both groups were found to be nearly identical, with the exception of changes in axodendritic synapses: in group 1 their mass activation was moderate, in group 2 poorly manifested.

[Complex characteristics of an epileptogenic focus in intracerebral space-occupying processes according to the findings of electrocorticography, polarographic studies and electron microscopy].

The work discusses the results of a study of the overall electric activity of the cerebral cortex, its frequency analysis and integration in brain tumors attended with epileptic seizures. The changes in electric activity are correlated with the cortical ultrastructure and the oxygen balance in the brain tissue. The possible mechanisms responsible for the development, cessation or absence of epileptic seizures in the clinical picture of brain tumors are analysed.