Temporal lobe epilepsy: neuropathological and clinical correlations in 243 surgically treated patients

Abstract

The present study included analysis of data from 243 patients surgically treated for Temporal Lobe Epilepsy (TLE). Resection was confined to the temporal lobe, with at least two years of follow-up, and specimens sufficiently preserved to allow a precise evaluation of both lateral neocortex and hippocampus. The frequency of different types of lesion and hippocampal sclerosis (HS), isolated or associated with neocortical lesions, risk factors and surgical outcomes in relation to neuropathological findings were evaluated. We found tumours in 33% of patients, malformations of cortical development (MCD) in 45%, isolated HS in 14%, no lesion in 5% and less common lesions in 3%. HS was present in 8% of tumour cases and 70% of MCD. Statistical analysis of antecedents was significantly associated only with febrile seizures (FS). In MCD patients with no history of FS, a strong association between HS and duration of epilepsy was revealed. A Class I outcome was identified in 87% of cases with tumours and 79% in cases with MCD. In 93 patients the antiepileptic drug therapy was withdrawn. Our findings show that MCD, which is significantly associated with HS, is the most common lesion in TLE and support the concept that an optimal outcome is obtained when mesial and neocortical structures are removed. FS are particularly relevant in patients with focal cortical dysplasia and HS.