Abstracts

Rationale: Children with refractory epilepsy associated with Tuberous Sclerosis Complex have multiple features that categorize them as challenging surgical candidates, including multiple indistinct and often overlapping seizure types. Subclinical seizures may be undetected on scalp recordings. We aim to compare characteristics between individuals with and without TSC who have undergone evaluation in the epilepsy monitoring unit (EMU; phase I) followed by implantation of stereo-EEG electrodes (phase II) within the last two years to identify features unique to individuals with TSC.

Methods: A retrospective chart review identified all patients who underwent stereo-EEG evaluation for epilepsy surgery at our institution preceded by at least 1 phase I evaluation between April 29, 2019 and May 7, 2021. Number of seizure types, days between phase I and phase II evaluations, discrepancies between seizures detected in phase I and II evaluations, duration of stereo-EEG, and ages of individuals during phase I and phase II evaluations were compared between individuals with and without TSC.

Results: 78 individual patients meeting criteria were identified (ages ranging between 14 to 241 months), with 80 total admissions for stereo-EEG. 31 patients had epilepsy due to TSC (20 female, 11 male) and 47 patients had other structural, genetic, or unknown etiologies (17 female, 30 male). Patients with TSC had more seizure types (mean 2.88, SD= 2.0) than those with other diagnoses (mean 2.02, SD= 1.38; p=0.027) but semiology or localization in phase II differed from phase I in the majority of patients in both groups (81% of patients with TSC, 67% of patients without TSC). Age was a significant factor, with children younger than 48 months being more likely have differing phase I and II findings than individuals older than 48 months (X²(1, N=80) = 5.0599, p= 0.0245). Patients with TSC had a shorter wait time between phase I and phase II studies (p=0.0095) and were younger at both phase I (p< 0.0002) and phase II (< 0.0001) evaluations than those without TSC. Mean sEEG duration was not significantly different between the two groups (X²(1, N=80) =0.1524, p= 0.1524).

Conclusions: Our results support the complexity of individuals with TSC affected by epilepsy, and highlight the similarities and differences to other etiologies of epilepsy requiring the utilization of invasive monitoring to further delineate the epileptogenic zones(s). The younger age and shorter time between phase I and II evaluations in patients with TSC may be a result of greater disease severity, but also suggests a more favorable view toward epilepsy surgery by both families and referring physicians of patients in this population.

Funding: Please list any funding that was received in support of this abstract.: None.