Resection extent versus postoperative outcomes of seizure and memory in mesial temporal lobe epilepsy

SummaryObjectivesTo investigate the effects of the resection of hippocampus and temporal neocortex on postsurgical seizure and memory outcomes in mesial temporal lobe epilepsy (mTLE) patients.MethodsSixty-eight mTLE patients underwent pre- and postsurgical brain magnetic resonance imaging (MRI). The patients were divided into seizure-free group (SF, N=54) and non-seizure-free group (NSF, N=14). The resection length of hippocampus was determined by the difference between presurgical and postsurgical hippocampus lengths in MRIs. The lengths of resected temporal gyri were measured on three-dimensional MRI reconstruction. Among SF group, 37 patients performed pre- and postsurgical neuropsychological tests. The postsurgical memory decline (PMD) was calculated by subtracting postsurgical memory score from presurgical one in verbal and visual memory tests.ResultsThe resection length of hippocampus in SF was significantly longer than in NSF (32.7±7.7mm versus 25.1±7.3mm, t-test, p=0.002), regardless of intersubject difference in the extent of hippocampal sclerosis (logistic regression, p=0.003) while the resection lengths of the lateral temporal gyri were not different between SF and NSF. Overall postsurgical change of verbal or visual memory was not significant. However, regression analysis showed a significant correlation between the resection length of inferior or basal temporal gyrus and verbal PMD (p