Responsive neurostimulation in pediatric patients with drug-resistant epilepsy

OBJECTIVE Medically refractory epilepsy remains a therapeutic challenge when resective surgery is not a practical option and indirect neurostimulation efficacy may be limited. In these instances responsive neurostimulation (RNS) has been used in adults, with good outcomes in most patients. However, the utility of RNS in children and young adults has not been systematically explored. In this study, the authors present a single institution’s experience with RNS in pediatric patients. METHODS A single-center retrospective chart review of patients who underwent RNS implantation at Phoenix Children’s Hospital during the 4-year period between January 2018 and December 2021 was performed. RESULTS Following evaluation for epilepsy surgery, 22 patients underwent RNS implantation using different anatomical targets depending on the predetermined epileptic focus/network. In the cohort, 59% of patients were male, the mean age at implantation was 16.4 years (range 6–22 years), and the mean follow-up time was 2.7 years (range 1.0–4.3 years). All patients had a preoperative noninvasive evaluation that included MRI, video-electroencephalography, and resting-state functional MRI. Additionally, 13 patients underwent invasive monitoring with stereo-electroencephalography to help determine RNS targets. All patients had variable positive responses with reduction of seizure frequency and/or intensity. Overall, seizure frequency reduction of > 50% was seen in the majority (86%) of patients. There were two complications: one patient experienced transitory weakness and one generator failed, requiring replacement. A patient died of sudden unexpected death in epilepsy 3 years after implantation despite being seizure free during the previous year. CONCLUSIONS RNS used in children with medically refractory epilepsy improved seizure control after implantation, with decreases in seizure frequency > 50% from preoperative baseline in the majority of patients. Preliminary findings indicate that functional MRI and stereo-electroencephalography were helpful for RNS targeting and that RNS can be used safely even in young children.