Abstracts

The investigation examined the extent of atrophy in ipsilateral and contralateral hippocampus and extrahippocampal temporal lobe regions in patients with unilateral temporal lobe epilepsy (TLE). 44 patients with ictal EEG confirmed unilateral TLE (20 left and 24 right) and 40 healthy controls underwent high resolution MRI with quantitative volumetric processing of hippocampus and temporal neocortex. Volumes were obtained of total temporal neocortex as well as parahippocampal and inferior, middle, superior and occipitotemporal lobe gyri using the methods of Kim et al. (2000). Volumetric data were examined using multivariate analysis of covariance with intracranial volume (ICV) and age as covariates. Ipsilateral hippocampal volumes were significantly (p [lt] 0.001) reduced in both the left (-20.6%) and right (-20.7%) TLE groups while contralateral hippocampal volumes were not significantly reduced for either the left (-6.1%) or right (-7.7%) TLE groups. Volumetric reductions in ipsilateral total temporal neocortex were comparatively modest but significant (p [lt] 0.001) for both the left (-7.7%) and right (-6.1%) TLE groups, while contralateral temporal lobe gray matter volumes were not significantly reduced for either the left (-2.3%) or right (-2.1%) TLE groups. Examining specific extrahippocampal temporal lobe regions, left TLE patients exhibited significant (p [lt] 0.01) atrophy in the gray matter of the left parahippocampal (-16.5%) and superior temporal gyri (-13.9%). Right TLE patients exhibited significant (p [lt] 0.05) volumetric reduction in the right ipsilateral temporal pole (-11.4%). Left and right TLE groups exhibit similar patterns regarding the presence and magnitude of volumetric abnormalities in ipsilateral and contralateral hippocampus and temporal neocortex, with significantly greater abnormality in ipsilateral hippocampus (approximately 20%) compared to ipsilateral temporal neocortex (approximately 6-7%). Volumes of contralateral hippocampus and temporal neocortex are not statistically different from controls. There was less symmetry in the patterns of atrophy within specific ipsilateral extrahippocampal temporal lobe regions in left (parahippocampal and superior temporal gyrus) versus right (temporal pole) gray matter. (Supported by NIH 2RO1 NS37738, and MO1 RR03186 (General Clinical Research Center).)