Introduction: The optimal surgical treatment for cavernous-malformation-related temporal lobe epilepsy (CRTLE) is still controversial, because it frequently involves hippocampus as an epileptogenic zone. In those cases, simple tumor resection cannot necessarily result in postoperative seizure freedom. Therefore, more aggresive procedures such as lobectomy or hippocampectomy are considered as surgical options. However, it is believed that the impact of them on neuropsychological functions is not negligible, especially if the lesion is located in the dominant hemisphere. To solve this question of how to balance postoperative seizure outcomes and neuropsychological outcomes, here we describe our unique surgical strategy for CRTLE, considering hippocampal transection (HT), in which the longitudinal hippocampal circuits are disrupted by transecting the pyramidal layer of the hippocampus in 5-mm intervals, in addition to tumor resection.

Methods: From 2005 to 2013, additional HT has been performed for 6 patients with CRTLE. Patient information including side of operations, follow-up periods, seizure outcome, and preoperative and postoperative (between 6 months and 12 months) Wechsler Memory Scale-Revised (WMS-R) has been collected.

Results: 2 cases of HT was performed on the dominant side and 4 cases on the non-dominant side. In the mean follow-up of 68.7 months [range 20-119], the postoperative seizure outcome is as follows: Engel class I in 5 cases (83.3%) and II in 1 case (16.7%). Perioperative changes in WMS-R score were as follows; in verbal memory, 92.5 preoperatively versus 99.7 postoperatively (P=0.403), in delayed recall, 88.3 versus 98.5 (P=0.25), and in general memory, 92.5 versus 99.5 (P=0.459). Overall, no patient presented with the more than 20% decline in any of the WMS-R scores postoperatively.

Conclusions: Postoperative seizure outcomes are excellent in our study with favorable postoperative memory outcomes. Although it did not reach the statistical significance, memory functions were rather improved postoperatively.In patients with CRTLE, additional HT is a considerable treatment option.

Patient Care: It can be helpful to improve the prognosis of patients with CRTLE. We can achieve excellent seizure outcomes without postoperative memory impairment or sometimes with better postoperative memory functions.

Learning Objectives: By the conclusion of this session, participants should be able to discuss, in small groups, the optimal surgical treatment for CRTLE, validity of HT, and the physiological mechanism of how hippocampal transection works.

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