Abstracts

Rationale: The responsive neurostimulation (RNS) system is an adjunctive treatment for pharmacoresistant partial onset seizures with 1 or 2 foci available to patients 18 or older since the FDA approval of the RNS device in 2013. We present the first use and preliminary therapeutic benefit of the RNS system in two pediatric patients. Methods: The RNS device was implanted in two children suffering from frequent disabling seizures resistant to medical therapy. Medical history, RNS lead placement and preliminary outcome are presented below. Results: CASE 1: A 14-year old non-ambulatory, non-verbal male with severe developmental delay and history of clinically significant aberrant behaviors was offered compassionate RNS placement for medically refractory epilepsy (MRE) with bilateral seizure onsets. He failed every antiepileptic medication. Previous right (R) frontal lobectomy, corpus callosotomy, and VNS procedures all resulted only in temporary seizure reduction. Subsequent palliative left (L) temporal lobectomy, with partial L frontal resection and L parieto-occipital disconnection had no worthwhile benefit. Neuropathology revealed diffuse multilobar Type 1 cortical dysplasia, despite normal MRI. The RNS system was implanted with R temporal and L frontal cortical strip placement. Additionally, R and L thalamic depth electrodes were placed, but not connected to the RNS device, for possible future use. At 8 months follow up (FU), cortical stimulation has resulted in sustained reduction in seizure frequency, with 1/day or no daytime seizures (down from 4/day), reduction in morning events, and behavioral/functional improvements noted at home and school. CASE 2: A 9-year-old R-handed girl suffering from MRE with MRI evidence of a small watershed infarct on the L and co-morbid panhypopituitarism was referred for pre-surgical evaluation. Her seizures started at 18 months and became intractable at age 5-6, slowing her academic progress and causing safety concerns over frequent falling. Invasive monitoring with grid and strip electrodes identified an unresectable seizure focus in the eloquent cortex of the L posterior frontal and parietal lobes. RNS device was implanted with cortical leads placed at the putative seizure focus. At 5 months after surgery, the patient's seizure frequency decreased from 12/month to about 2/month. The events are milder, she no longer falls, and became more aware and talkative, with an improved ability to pay attention at school. There were no surgery-related complications or adverse events noted in either case. Conclusions: Compassionate use of the RNS device provided a preliminary therapeutic benefit in two pediatric patients. The treatment was well tolerated in both cases. While larger, placebo-controlled studies, such as those required for FDA approval, are needed to determine the applicability of our findings to the general pediatric epilepsy population, our results suggest that responsive neurostimulation may be a reasonable option for children with intractable seizures whose conditions warrant off-label use of a surgical device. Funding: Not externally funded