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 January 31, 2018. 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 and the Neuroblate Laser Ablation System. Results: Twenty-five patients (thirteen males, twelve females) with tuberous sclerosis complex and refractory epilepsy underwent stereotactic minimally invasive monitoring or treatment. Ages ranged between 1 and 17 years. Of these patients 32% (n=8) had a history of prior epilepsy surgery. Three of the 25 patients underwent ablation without sEEG. Twenty-two patients underwent sEEG to localize seizure onset prior to ablation and of these, twenty-one underwent ablation during the same or subsequent hospitalization. One patient did not undergo ablation after sEEG due to an eloquent seizure focus. Two patients underwent sEEG following ablation of a dominant tuber, and both had additional ablation prior to discharge. In total, eight patients underwent post-ablation sEEG monitoring with three undergoing additional ablations. Seven of the twenty four patients (29%) in this series were seizure free (Engle I) at 6 months. Five of eighteen patients (28%) seen at 1 year remained seizure free (Engle I). Seven patients (29%) experienced no change in seizure frequency following ablation (Engel IV) at 6 months and six of the eighteen patients (33%) with 12 month follow up data had unchanged seizure frequency (Engel IV). Of the twenty-four total patients, fourteen (58%) experienced transient periods of complete seizure freedom ranging between 1 week and 4 years prior to seizure recurrence (mean 7.3 months). Conclusions: Stereotactic minimally invasive surgery may represent a viable option for the treatment of children severely affected by medically refractory epilepsy associated with tuberous sclerosis complex. Children with multi-focal, disparately located lesions subserving multiple seizure onset zones 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 long-term efficacy of minimally invasive surgery in TSC. Funding: No funding