Abstracts

Rationale: Recently, considerable attention has been focused on the distinctions between mesial temporal lobe epilepsy (MTLE) and cryptogenic, idiopathic, or non-MTLE as defined with paradoxical temporal lobe epilepsy (PTLE). Previous investigations revealed high risk for memory decline following anterior temporal lobectomy (ATL) in patients with PTLE compared with patients with MTLE. In the present study, the authors investigated whether transsylvian selective amygdalohippocampectomy (TSA) which spared unaffected brain tissue from surgery has different effects on memory function with PTLE. Methods: Seventy patients exhibited the syndrome of MTLE (left 33, right 37), while 32 patients (left 17, right 15) were without the syndrome (PTLE). All patients received comprehensive neuropsychological testing of verbal and nonverbal memory, attention, delayed recall before and 1 month or 1 year after TSA. Separate repeated-measures multivariate analysis of variance (MANOVA) were performed for these intervals with memory scores. Results: In MTLE, the results of MANOVA indicated that right TSA patients showed significant improvements in verbal memory (preoperative vs. 1month postoperatively, p<0.0001; and preoperatively vs. 1 year postoperatively, p=0.0012), nonverbal memory (preoperative vs. 1month postoperatively, p=0.0012; and preoperatively vs. 1 year postoperatively, p=0.0099), delayed recall (preoperative vs. 1month postoperatively, p=0.0081; and preoperatively vs. 1 year postoperatively, p=0.0181) at both 1 month and 1 year follow-ups. There were no significant changes in verbal memory, nonverbal memory, attention, or delayed recall at either 1 month or 1 year follow-up. In PTLE, left TSA patients revealed significant deterioration in verbal memory (preoperative vs. 1month postoperatively, p=0.0002; and preoperatively vs. 1 year postoperatively, p=0.0074) at both 1 month and 1 year follow-ups. In right TSA for PTLE, verbal memory (preoperative vs. 1month postoperatively, p<0.0001; and preoperatively vs. 1 year postoperatively, p=0.0067), attention (preoperative vs. 1month postoperatively, p=0.0016; and preoperatively vs. 1 year postoperatively, p=0.0378) and delayed recall (preoperative vs. 1month postoperatively, p=0.0267; and preoperatively vs. 1 year postoperatively, p=0.0396) were improved immediately and were maintained for 1year. Conclusions: The results of the present study indicated that TSA for bilateral MTLE and right PTLE is effective for preservation and improvement of memory function. However, verbal memory decline observed 1 month after TSA for left PTLE was persistant 1 year after surgery.