Quantitative MRI volumetry of the entorhinal cortex in temporal lobe epilepsy

The entorhinal cortex (Brodmann's area 28) is located at the anterior aspec t of the parahippocampal gyrus ventral to the amygdala and the hippocampus. It is reciprocally interconnected with the hippocampus via glutamatergic p athways. We investigated whether the entorhinal cortex is damaged in human temporal lobe epilepsy (TLE). The volume of the entorhinal cortex was measu red using magnetic resonance imaging (MRI) in 36 patients with cryptogenic TLE and in 21 controls. The mean volumes of the entorhinal cortex on the fo cal side did not differ from controls. In Ii of 36 patients, however, the e ntorhinal cortex volume was reduced by 25%. Entorhinal volume correlated wi th hippocampal volume in TLE (ipsilaterally, r = 0.454, P < 0.01; contralat erally, r = 0.340, P < 0.05). Further, 64% of patients with 25% entorhinal cortex damage had ipsilateral hippocampal atrophy. On the other hand, right focal TLE patients with hippocampal atrophy had a 19% volume reduction of the ipsilateral entorhinal cortex (P < 0.05). The Volume of the entorhinal cortex correlated with the duration of TLE (r = -0.335, P < 0.05). The pres ent study indicates that the entorhinal cortex might be damaged in a subpop ulation of patients with cryptogenic TLE. In most cases, volume reduction w as associated with hippocampal damage. These data suggest that entorhinal d amage contributes to the symptomatology in TLE. (C) 2000 BEA Trading Ltd.