TEMPORAL-LOBE EPILEPSY CAUSED BY MESIAL TEMPORAL SCLEROSIS AND TEMPORAL NEOCORTICAL LESIONS - A CLINICAL AND ELECTROENCEPHALOGRAPHIC STUDY OF 46 PATHOLOGICALLY PROVEN CASES

This study aims to determine whether there are important clinico-elect rical differences between patients with temporal lobe epilepsy (TLE) s econdary to mesial temporal sclerosis (MTS) and those with TLE seconda ry to a discrete temporal neocortical lesion (NL). The case histories, interictal EEG, seizure semiology, ictal EEG and postoperative outcom e of 46 pathologically proven patients (31 MTS and 15 NL) were compare d. A history of febrile convulsions (FC) was more common in MTS patien ts (58% versus 26%, P < 0.05), as was a history of a significant cereb ral event at <4 years of age (22% versus 0%, P < 0.05). There were no statistically significant differences in the incidence or nature of au ras. No statistically significant differences between the groups were found in the interictal-EEG. With ictal semiology dystonic posturing o ccurred more frequently in MTS patients (mean 52% versus 26%, P < 0.05 ). Facial grimacing/twitching occurred earlier in the seizures of NL p atients (median 19 s versus 35 s, P < 0.05). There was art increased f requency of fast rhythmic sharp waves (>4 Hz) in the ictal-EEG of MTS patients (mean 81% versus 60%, P = 0.05). The patients with NL develop ed bilateral ictal EEG changes more often (mean 55% versus 26%, P < 0. 05) and more rapidly (mean 23 s versus 74 s, P < 0.005). The onset of ictal EEG seizure activity was bilateral more often in patients with N L (20% versus 4%, P < 0.005). There were no significant differences be tween the two groups for any of the video-EEG features, in terms of wh ether or not the feature occurred at least once in an individual patie nt. There was a tendency for MTS patients to have a higher seizure-fre e post surgical outcome (87% versus 60%, P = 0.057). However all the N L patients who were not free of seizures had had an incomplete lesion resection. We conclude that there are a number of clinico-electrical d ifferences between patients with mesial TLE (MTLE) and patients with n eocortical TLE (NCTLE), but that none of these are sufficient to allow a distinction to be made in an individual patient.