Electrical Stimulation for the Induction of Seizures is Safe, Well-tolerated and High-Yield in Children with Drug-Resistant Epilepsy.

Introduction: One third of children with epilepsy develop drug-resistant epilepsy (DRE). Epilepsy surgery is the treatment for DRE, and selecting the surgical target typically requires recording spontaneous seizures during intracranial monitoring with stereoelectroencephalography (sEEG). In adults, induced seizures have been shown to help define surgical targets and are associated with superior surgical outcomes. No published studies focus on the safety, tolerability, and yield of electrical stimulation for the induction of seizures (ESIS) in children.

Methods: Stimulation at 1 Hz and 50 Hz was performed prospectively and comprehensively (all gray matter channels) during sEEG in children and young adults with DRE. Induced seizures were categorized into four groups: electroclinical habitual, clinical habitual (aura), subclinical and non-habitual. Primary safety outcome was use of rescue medication. Patient and caregiver tolerability were assessed by questionnaire. Yield was measured as induced seizure rate.

Results: Sixty-seven patients (n=30 female) were included, ages 1-21 years (mean ± SD, 11.1 ± 5.7). Three patients participated twice, yielding 70 patient admissions. n=10,135 stimulation trials were performed, requiring 175 ± 61 minutes per patient. Only one seizure required acute rescue medication. Patient and caregiver tolerability ratings were overall favorable and improved from pre- to post-session. At least one induced seizure was obtained in 62/70 (89%) patients, representing 283/10,135 trials (2.8%). Combined, habitual seizures and habitual auras accounted for most induced seizures (58%); non-habitual seizures were uncommon (12%). Of those with induced seizures, multiple seizure types occurred in 28/62 (45%). Seizures were induced at both 1 Hz and 50 Hz in 22/67 patients (33%).

Significance: Comprehensive seizure stimulation during sEEG is safe, well-tolerated, and high-yield in children. Both 1 Hz and 50 Hz stimulation induce seizures. These findings motivate a more systematic utilization of ESIS in pediatric EMUs.