Abstracts

Rationale: Tuberous Sclerosis Complex (TSC) is associated with medically refractory epilepsy and developmental delay in children. Seizures that begin in young patients are often refractory and may contribute to development delay. Some patients with TSC may have a single focus and may benefit from cortical resection, however, many children with TSC develop uncontrolled seizures in association with multiple epileptogenic tubers with poorly localizable/lateralizable VEEG findings. Although the pre-surgical findings in these children are not associated with surgically amenable epilepsy foci, we considered an alternative strategy beyond medication trials given the overall risks of continued, frequent medically refractory seizures. To identify patients who might benefit from surgery, and to maximize outcome, some subjects undergo bilateral implantation of subdural and/or depth electrodes. This study examines the utility of bilateral subdural electrode studies in medically refractory TSC. Methods: A retrospective analysis of all 52 patients undergoing epilepsy surgery from 2000 to 2008 for TSC identified 20 patients with bilateral strip implantation. The preoperative surgical workup, intracranial EEG findings, surgical intervention and outcome was performed to identify the features which predict successful lateralization. Surgical outcomes for patients at least six months following resection were classified utilizing the Engel system. Results: 14/20 patients undergoing bilateral strip surveys went on to have a focal resection. One is pending further resection. In 7/14 patients, multiple resections were undertaken. 5 patients had multi-focal, non-resectable or non-lateralizable onsets and no further surgery was performed. Of the patients undergoing a resection, 7/14 have Engel Class I surgical outcomes with a median follow-up of 25 months (6 months - 4 years). Conclusions: This retrospective study illustrates the role of invasive monitoring in medically refractory TSC for patients with poorly lateralized interictal and ictal VEEG data. Despite non-lateralizable/non-localizable pre-operative evaluations, 74% of the patients studied invasively had focal (or multi-focal) resectable regions and, of those, 50% are now seizure free.