CORTICAL AND HIPPOCAMPAL VOLUME DEFICITS IN TEMPORAL-LOBE EPILEPSY

Purpose: To use quantitative magnetic resonance imaging (MRI) methods to examine the extent of volume abnormalities in the hippocampus and i n extrahippocampal brain regions in localization-related epilepsy of t emporal lobe origin (TLE). Methods: Hippocampal, temporal lobe, and ex tratemporal lobe volumes were examined with 3-mm spin-echo coronal MRI scans in patients with unilateral TLE who were candidates for tempora l lobe resection. Measures were adjusted for normal variation due to i ntracranial volume and age based on 72 healthy male controls. Group di fferences between 14 male TLE [7 left TLE (LTLE), 7 right TLE (RTLE)] patients and a subset of 49 age range-matched controls were examined w ith analysis of variance (ANOVA). Results: As compared with controls, patients with TLE had smaller temporal lobe and frontoparietal region gray matter volumes, bilaterally, smaller temporal lobe white matter v olumes bilaterally, and larger ventricular volumes. In contrast to the se bilateral tissue volume deficits, hippocampal volume deficits in TL E were ipsilateral to the epileptogenic temporal lobe. Conclusions: Ex trahippocampal volume abnormalities were bilateral and occurred in bot h temporal and extratemporal cortical regions in TLE, whereas hippocam pal deficits were related to the side of the epileptogenic focus. Thes e data suggest that brain abnormalities in TLE are not limited to the epileptogenic region.