[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. In epilepsy this ratio was 10-12 times higher than in tumours unattended with seizures. Activation of AD synapses should be considered as an ultrastructural manifestation of epileptization of the neuron while its extension should be seen as a criterion of the morphological diagnosis of the disease itself.