PREFERENTIAL NEURONAL LOSS IN LAYER-III OF THE ENTORHINAL CORTEX IN PATIENTS WITH TEMPORAL-LOBE EPILEPSY

We report a characteristic pattern of neuropathological change in the entorhinal cortex (EC) from four patients with temporal lobe epilepsy. Specimens of the EC were obtained during the surgical treatment of in tractable partial seizures and were studied by light microscopy in Nis sl-stained sections. A distinct loss of neurons was observed in the an terior portion of the medial FC in the absence of apparent damage to t emporal neocortical gyri. Cell loss was most pronounced in layer III, but also noticed in layer II, particularly in the rostral field. A sim ilar pattern of neurodegeneration in the EC was found in all specimens examined though the degree of neuronal loss varied between cases. The se observations provide neuropathological evidence for an involvement of the EC in temporal lobe epilepsy. Since the EC occupies a pivotal p osition in gating hippocampal input and output, our results further su pport previous suggestions that dysfunction of this region may contrib ute, either independently or in concert with Ammon's horn sclerosis, t o epileptogenesis in humans.