Abstracts

Rationale: Multimodal studies using positron emission tomography (PET), magnetic resonance imaging (MRI) and scalp electroencephalography (EEG) have demonstrated the topographic correlation between positions of tubers and the site of onset of paroxysmal discharges in pediatric patients with tuberous sclerosis complex (TSC) with medically refractory epilepsy. However, little is available in the literature utilizing stereoelectroencephalography (sEEG) in describing the location of the ictal onset zone as deep within the tuber center, or in more superficial tuberal or perituberal regions. The aim of this study was to better understand networks within epileptogenic tubers from data obtained from sEEG recordings in pediatric patients with TSC. Methods: This is a single center retrospective analysis of pediatric patients with TSC who underwent sEEG followed by MRI-guided stereotactic laser ablation. Analysis of intraoperative sEEG data to include the contacts of individual depth electrodes recording the highest number of typical seizures during monitoring were performed. The ictal onset zone was considered ‘’superficial’’ if the ictal onset was in the single most superficial electrode close to the cortical surface, vs ‘’deep’’ if ictal onset was from the remainder of electrodes sampling deeper regions in the brain. Results: This study included twenty-two patients with TSC who underwent sEEG followed by MRI-guided stereotactic laser ablation between October 2013 and February 2018. Eleven patients (%50) were female. The mean age at surgery was 5.2 (range 1-17) years. Localization of seizure foci in all cases were done through method of stereotaxy consisted of ROSA robotic guidance. The mean duration of monitoring was 131 (range 62-256) hours. The mean total hospital stay was 14 (range 5–45) days. The mean total number of clinical seizures recorded during monitoring was 30.4 (range 4-90). The majority (82%; n=18) had an ictal onset within the more distal contacts of the depth electrode. The remainder (18%; n=4) had an ictal onset in the most superficial contact of the depth electrode. Conclusions: These findings support the use of sEEG in localization of seizure onset in pediatric patients with refractory epilepsy and tuberous sclerosis complex. Additional studies examining propagation networks to more superficial and surrounding regions in intracranial recordings may assist in understanding why scalp EEG recordings are often inadequate in exact localization of seizure onset in severely affected children. Funding: No funding