Introduction: Surgical approaches for cavernous-malformation-related temporal lobe epilepsy (CRTLE) are debatable, because of the epileptogenesis of regions surrounding the tumors as well as the hippocampus. Here we describe our unique surgical strategy, adding hippocampal transection (HT) or hippocampectomy (HC) for co-existing hippocampal abnormalities to lesionectomy
Methods: From 2005 to 2016, 16 cases of CRTLE were treated surgically. We routinely performed intraoperative electrocorticography on the hippocampus just before and after the resection of the tumor with hemosiderin rim. When residual spikes were confirmed after the resection, additional HT or HC was performed, depending on the laterality of the lesion, memory function, and MRI abnormalities in the hippocampus. Consequently, seven additional HTs, (dominant:3, non-dominant:4), seven additional HCs (dominant:5, non-dominant:2), and two lesionectomies alone were performed. Patient information including seizure outcomes and pre- and post-operative (12 months) Wechsler Memory Scale-Revised (WMS-R) was collected and statistically analyzed.
Results: With the median follow-up of 36.5 months [range 26-127], the postoperative seizure outcome was as follows: Engel class I in 14 cases (87.5%) and II in two cases (12.5%). Patients with HT and those operated on the non-dominant side demonstrated better memory outcomes in verbal memory (versus HC: +6.0 versus -19.6 p=0.049, versus dominant: +10.2 versus -19.5 p=0.012) and in delayed recall (versus HC: +7.3 versus -13.6 p=0.085, versus dominant: +12.0 versus -14.5 p=0.011). Overall, only two patients (12.5%) experienced >20% declines in any WMS-R indices.
Conclusions: Our novel surgical strategy resulted in favorable seizure and memory outcomes. Patients with HT and non-dominant-sided operations demonstrated better postoperative memory outcomes.
Patient Care: Conventionally, patients with CRTLE were treated with just the lesionectomy, which oftentimes resulted in delayed seizure recurrence due to the epileptogenesis from the hippocampus. Recurred seizure in this entity tends to be intractable, and thus, early intervention is desirable. Hence, our one-stage surgery to resect the tumor and address epileptogenic zones such as the hippocampus at once is beneficial for patients with this entity. However, it is believed that the impact of these aggressive procedures on neuropsychological function is not negligible, especially if the lesion is located in the dominant hemisphere or if the resected hippocampus appears normal on the preoperative MRI or if the preoperative memory function is satisfactory, as is the same as non-tumor-related temporal lobe epilepsy. The research described here allows us to solve this question of how to balance postoperative seizure outcomes and neuropsychological outcomes, and thus, could be beneficial for patients with CRTILE.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the importance of the hippocampus as an epileptogenic zone in patients with cavernous-malformation-related temporal lobe epilepsy, 2) Discuss, in small groups, the utility of HT, and 3) Identify an effective treatment for CRTLE by taking our novel surgical strategy into consideration.