MEDIAL TEMPORAL-LOBE EPILEPSY WITHOUT HIPPOCAMPAL ATROPHY

The incidence and structural basis of nonlesional medial temporal lobe epilepsy (MTLE) without hippocampal atrophy (HA) is not known. Report s suggest that 5-15% of patients with hippocampal sclerosis (HS) do no t have HA. We reviewed 57 patients with MTLE who underwent magnetic re sonance imaging (MRI) volumetric studies, anteromedial temporal lobect omy (TL), and quantitative cell counts of the resected hippocampus and who had at least 1 year of surgical follow-up. We compared demographi c, pathologic, and outcome data among patients with and without HA. Te n of the 57 patients did not have HA. Nine of the 10 patients had dept h EEG for localization of seizure onset because of discordance or insu fficient localization. Five patients had pathologic evidence of HS. Lo nger duration of epilepsy correlated inversely with the presence of HA . Outcome was not significantly different between patients with and wi thout HA. We conclude that the incidence of MTLE and HS without HA. is 9%. Except for duration of epilepsy, there were no differences in the clinical syndrome or surgical outcome of patients with and without HA .