Abstracts

Rationale: We have already reported that selective amygdalohippocampectomy (SAHT) via the inferior temporal gyrus using neuronavigation system provides in excellent epilepsy control in patients with refractory mesial temporal lobe epilepsy (MTLE). This surgical procedure is less invasive and safer. Here, we analyzed the outcome of memory function after this surgical procedure. Methods: Nighteen patients with mesial temporal lobe epilepsy have undergone the SAHT procedure for MTLE via the inferior temporal gyrus. Among them, 12 patients utilized the Wechsler Memory Scale-Revised (WMS-R) score to evaluate memory function both just before and 6 to 12 months after SAHT. The lesions were located on verbal dominant hemispheres in 5 cases and on verbal non-dominant hemispheres in 7 cases. Results: The postoperative outcomes of 18 of all 19 cases were seizure free categorized as Engel's class I. The pathology of these 18 cases was hippocampal sclerosis. The other case resulted in Engel's class IIa. The pathology of this case was cortical dysplasia. The pre-operative verbal, visual, and total memory scores were 78.2±7.8 (Ave±SE), 93.7±8.7, and 79.0±7.8, respectively. Post-operative scores were 87.6±11.0, 101.2±11.5, and 91.3±10.9, respectively. Post-operative scores of all three scales were significantly improved compared to pre-operative scores. The scores of attention and delayed recall were also significantly improved post-operatively. The cases of verbal dominant hemispheres revealed significant improvement of visual memory. In contrast, the cases of verbal non-dominant hemispheres revealed significant improvement of verbal and total memory. More than 10% of verbal memory was lost in one case of dominant hemisphere MTLE. Conclusions: Not only good seizure outcome but also improvement of memory function, especially the verbal memory in non-dominant and the visual memory in dominant hemisphere MTLW, can be expected with SAHT via the inferior temporal gyrus preserving the temporal stem.