MRI evidence of mesial temporal sclerosis in sporadic "benign" temporal lobe epilepsy

OBJECTIVE: To determine whether there is MRI-detectable mesial temporal sclerosis (MTS) in patients with sporadic benign temporal lobe epilepsy (BTLE). METHODS: Brain MRIs were obtained from 101 consecutive, unrelated patients (51 women; mean age 37.3 +/- 17.5 years; range 10 to 83 years) with BTLE, who reported rarely or never having had seizures at the time of long-term (> 2 years) follow-up. The mean age at seizure onset was 22.3 +/- 17.4 years; the mean duration of epilepsy was 16.4 +/- 14.1 years. MRI diagnosis of MTS was based on the occurrence of hippocampal formation atrophy on T1 slices, an increased mesial temporal signal intensity alteration on fluid-attenuated inversion-recovery (FLAIR) or T2 images, or both. RESULTS: Thirty-nine of 101 patients (38.6%) had MRI evidence of unilateral MTS (19/39 left MTS, 20/39 right MTS), which correlated with the epileptiform activity. Hyperintense FLAIR and T2 signal with or without atrophy was observed in 24 of 39 individuals. There was no difference between patients with or without MRI-detected MTS in age at onset and duration of epilepsy. Family history of epilepsy or febrile convulsions (FCs) was more frequent in patients with MRI-detected MTS (36%) as compared with patients with normal MRI (22.7%), but the difference was not significant. Antecedent FCs were more frequent (p = 0.03) in patients with MRI-detected MTS (9/39; 23%) vs those with normal MRI (5/62; 8%). CONCLUSIONS: MRI-detected mesial temporal sclerosis is often encountered in patients with sporadic benign temporal lobe epilepsy.