The neuropathology of temporal lobe epilepsy: Primary and secondary changes in the cortical circuits and epileptogenicity | Neuropatología de la epilepsia del lóbulo temporal. Alteraciones primarias y secundarias de los circuitos corticales y epileptogenicidad

In this paper we consider the possibility that in both the primary and secondary epileptogenic regions there are similar changes in the neuronal circuits which induce epileptic activity. In the case of the primary epileptogenic regions, these changes occur non specifically following an initial lesion or precipitating factor (e.g. a tumour) which induces gliosis and neuronal loss around the lesion. These changes give rise to a perilesional synaptic reorganization (elimination of connections with or without the formation of new synapses) which causes the onset and continuation of epileptic activity. However, the changes in the circuits in the secondary epileptogenic regions are the result of epileptic activity originated in the primary epileptogenic region which is propagated by specific anatomical connections. This anomalous activity causes changes in the target region (gliosis and neuronal loss) which leads to epileptogenic synaptic reorganization similar to that occurring in the primary perilesional areas.