Abstracts

Rationale: Tuberous Sclerosis Complex (TSC) is a genetic condition associated with benign hamartomas, most notably in the brain. 80-90% of TSC patients have epilepsy, 50% of whom are drug refractory. Epilepsy surgery has historically been an under-utilized but important therapy, as even if a curative option is not possible, a reduction in seizure burden has the potential to ameliorate development and quality of life. The objective of this study was to retrospectively review children enrolled in the Hospital for Sick Children (SickKids) TSC Clinical Outcomes Database who have been evaluated for epilepsy surgery and determine factors related to decision-making surrounding type of surgery and outcomes.

Methods: The patient cohort was obtained from the SickKids TSC Clinical Outcomes Database (n=88), which includes paediatric patients with clinically and/or genetically confirmed TSC. Patients enrolled in the database between January 2019 and November 2022 were reviewed. Patient demographics were collected. Details surrounding epilepsy surgery evaluations and outcomes were gathered, as well as factors related to decision-making surrounding eligibility for epilepsy surgery and type of surgery.

Results: 33% of patients were considered for epilepsy surgery (n=29/88), with 59% of those patients undergoing epilepsy surgery (n=17/29). The median age at time of surgery was 3 years [1.8-13]. Of the patients that underwent epilepsy surgery, 29% underwent focal resective surgery (n=5/17) and 71% underwent neuromodulation (n=12/17), which included vagal nerve stimulation or deep brain stimulation. 3/5 of patients who underwent focal resective surgery were seizure-free at the 3-year follow-up. Focal surgical resection candidates had unilateral EEG findings, frequent seizures (daily to weekly) pre-surgery, tubers associated with ictal onset zone, and concordance across pre-surgical investigations. Neuromodulation candidates had multiple seizure types, multiple independent spike foci and generalized paroxysmal fast activity on EEG. Factors as to why patients did not undergo epilepsy surgery included bilateral EEG findings, seizure-freedom or seizure improvement, parental reluctance, discordance across pre-surgical investigations, and being determined as a high-risk surgical candidate.

Conclusions: The findings of this study are significant as they provide greater insight into eligibility and decision-making surrounding epilepsy surgery in our cohort, as well as demonstrate positive seizure outcomes post-surgery. Future work will examine patients who did not undergo epilepsy surgery, or who were not considered for epilepsy surgery initially, to determine if the criteria for consideration of epilepsy surgery can be broadened for future patients.

Funding: Cooper Robertson Foundation.