Microscopic Disorders of Cortical Development of Brain and theEtiopathogenetic Relevance of their Detection in Patients with TemporalLobe Epilepsy due to Hippocampal Sclerosis

Overview

Hippocampal sclerosis represents a common structural basis of temporal lobe epilepsy. However,the etiological factors and mechanisms leading to its development still remain unexplained. Inour study, we present neuropathological findings in the resected hippocampus and the pole of thetemporal lobe in 15 patients with hippocampal sclerosis. „Initial precipitating injuries“ that arethought to cause the development of hippocampal sclerosis (febrile seizures in early childhood,head injury or meningoencephalitis) were present in the history of 12 patients. In the remaining 3cases, no predisposing factors were found. Attention was paid to the histopathological identificationof disturbed neuronal migration and differentiation in the temporal lobe. These defects wereobserved in 7 cases; in three of these, no predisposing factors were stated in the patients’ histories.We suggest that in these cases, hippocampal sclerosis arises due to previously undetecteddisorders of cortical development. A latent neocortical malformation may also contribute to thedevelopment of hippocampal sclerosis in patients with an initial precipitating injury in anamnesis.Histopathological examination of resected epileptic brain tissue can provide insights into theindividual pathogenesis of epileptic disorders, especially by the detection of microscopic disordersof cortical development.

Key words:
epilepsy – mesiotemporal sclerosis – cortical dysplasia