Temporal lobe epilepsy with varying severity: MRI study of 222 patients

MRI was performed in 222 consecutive adult patients with temporal lobe epilepsy of varying severity from January 1991 to May 1993. The diagnosis of hippocampal sclerosis was established visually by three independent observers. The accuracy of visual assessment of hippocampal asymmetry was compared with volumetric measurements. Neuropathological correlations were obtained in 63 patients with refractory seizures. Temporal lobe abnormalities were observed in 180 patients (81%) as follows: hippocampal sclerosis in 122 (55%); developmental abnormalities in 16 (7.2%); tumours in 15 (6.8%); scars in 11 (5%); cavernous angiomas in 10 (4.5%); miscellaneous lesions in 6. MRI was normal or showed unrelated changes in 42 patients (19%). Visual assessment correctly lateralised hippocampal sclerosis in 79 of the 84 patients measured (94%). Temporal lobectomy confirmed the MRI data (side and aetiology) in all 63 operated patients. Patients with normal MRI had an older age of seizure onset and were more often drug-responsive than patients with hippocampal sclerosis. MRI showed temporal lobe abnormalities in 81% of epileptic patients with varying severity with good neuropathological correlation. Patients with normal MRI had a less severe form of the disease.