Temporal Lobe Resections

Abstract

Based on clinical studies with cortical recordings by Penfield and Jasper at the Montreal Neurological Institute (MNI) indicating temporal spike foci in a high number of epilepsy cases, temporal lobe resections for epilepsy have been started. Nowadays, the syndrome of mesial temporal lobe epilepsy (MTLE) constitutes a well-known entity accounting for 90–95% of temporal lobe epilepsies. Seizure freedom rates reported mainly range between 40% and 70% and marked reduction of seizure frequency between 60% and 90%. Left-sided resections seem to be critical leading to decline in verbal memory in a significant portion of patients. An extensive body of literature is available on different temporal approaches including modifications of lateral and mesial resection strategies, all aiming at the ideal combination of maximal seizure freedom and minimal cognitive impairment. Starting with anterior temporal lobectomy (ATL) in the 1950s, a tendency has been witnessed over the decades to reduce the extent of lateral resection in MTLE based on the hypothesis that smaller resections lead to the same favorable seizure outcome as ATL, but provide better cognitive function. Similarly, the extent of mesial resection has been modified hypothesizing that shorter mesial resections are advantageous with respect to the cognitive outcome while providing similar favorable seizure outcome as compared to larger mesial resections. According to the data available, it seems that these hypotheses cannot be maintained longer. While smaller lateral and shorter mesial resections have been shown to provide the same favorable results in terms of seizure outcome as compared to larger resections, no significant differences in cognitive outcome between more extended and more restricted lateral and mesial resections have been proven. Therefore, the surgeon should choose the approach according to his/her individual experience starting with ATL.