Abstracts

Rationale: Stereotactic MRI-guided laser ablation therapy is an emerging minimally invasive therapy utilized in treating medically refractory epilepsy associated with deep lesions such as hypothalamic hamartomas and mesial temporal sclerosis. Stereoelectroencephalography (SEEG) has enjoyed resurgence as a minimally invasive alternative in intracranial monitoring in epilepsy. Children with tuberous sclerosis complex (TSC) often have focal or multifocal onset epilepsy secondary to cortical tubers which may be amenable to minimally invasive monitoring and treatment. We describe our institution’s experience utilizing Stereotactic MRI-guided laser ablation with and without SEEG in treating refractory epilepsy in children with TSC. Methods: A retrospective chart review was performed identifying all children with TSC treated with MRI-guided stereotactic laser ablation for medically refractory epilepsy prior to May 31, 2017. All patients underwent a pre-surgical epilepsy evaluation followed by presentation in epilepsy surgery conference, where a general consensus for pursuing minimally invasive intracranial monitoring and/or treatment was reached. SEEG was accomplished with the ROSA surgical robot. Treatment of the epileptic foci was accomplished with the Visualase Laser Ablation System. Results: Twenty patients (ten males, ten females) with tuberous sclerosis complex and refractory epilepsy underwent stereotactic minimally invasive monitoring or treatment. Ages ranged between 1 and 17 years. Sixteen patients underwent sEEG to localize seizure onset prior to ablation. Three of these patients underwent post-ablation sEEG monitoring with two undergoing additional ablation.  One patient underwent sEEG following ablation of a dominant tuber, and had additional ablation prior to discharge. Following ablation, seven patients were clinically seizure free at last follow up, which ranged between 1 week and 6 months. Seven patients experienced transient periods of seizure freedom ranging between 1 week and 4 years prior to recurrence.  Two patients experienced freedom from status epilepticus or falls but continued to experience other seizure types following ablation at 3 months post-ablation. Two patients experienced seizure recurrence beginning in the postoperative period.  Two patient did not undergo ablation due to eloquent seizure focus or lack of localizing seizure onset. Eleven patients experienced a reduction in, or freedom from, seizures at the time of most recent follow up. Of these, one patient underwent a reoperation 2 years later with a craniotomy and subdural grid array and experienced seizure freedom at 5 months following resective surgery. Two patients reported increased seizure frequency at last follow up.  All but one of the eighteen patients undergoing minimally invasive surgery had a 1 or 2 day post-operative hospital stay. Conclusions: Stereotactic minimally invasive surgery may represent a viable option for the treatment of medically refractory epilepsy in tuberous sclerosis. Children with multi-focal, disparately located lesions subserving multiple seizure onset zones (SOZs) may avoid wide exposure via extensive craniotomy with minimally invasive techniques, translating into less morbidity and shorter hospital stays. Future study is required to refine the application of functional imaging modalities in improving localization of the seizure onset zone and to improve the efficacy of minimally invasive surgery in TSC. Funding: None.