Responsive neurostimulation for regional neocortical epilepsy.
OBJECTIVE
Surgical resection of seizure-producing brain tissue is a gold standard treatment for drug-resistant focal epilepsy. However, several patient-specific factors can preclude resective surgery, including a spatially extensive ("regional") seizure-onset zone (SOZ). For such patients, responsive neurostimulation (RNS) represents a potential treatment, but its efficacy has not been investigated in this population.


METHODS
We performed a multicenter retrospective cohort study of patients (N = 30) with drug-resistant focal epilepsy and a regional neocortical SOZ delineated by intracranial monitoring who were treated with the RNS System for at least 6 months. RNS System leads were placed at least 1-cm apart over the SOZ, and most patients were treated with a lead-to-lead stimulation pathway. Five patients underwent partial resection of the SOZ concurrent with RNS System implantation. We assessed change in seizure frequency relative to preimplant baseline and evaluated correlation between clinical outcome and stimulation parameters.


RESULTS
Median follow-up duration was 21.5 months (range 6-52). Median reduction in clinical seizure frequency was 75.5% (interquartile range [IQR] 40%-93.9%). There was no significant difference in outcome between patients treated with and without concurrent partial resection. Most patients were treated with low charge densities (1-2.5 µC/cm2 ), but charge density, interlead distance, and duration of treatment were not significantly correlated with outcome.


SIGNIFICANCE
RNS is a feasible and effective treatment in patients with drug-resistant regional neocortical seizures. Prospective studies in larger cohorts are necessary to determine optimal lead configuration and stimulation parameters, although our results suggest that lead-to-lead stimulation and low charge density may be effective in some patients.
['Ma|Brandy B|BB|', 'Fields|Madeline C|MC|', 'Knowlton|Robert C|RC|', 'Chang|Edward F|EF|', 'Szaflarski|Jerzy P|JP|0000-0002-5936-6627', 'Marcuse|Lara V|LV|', 'Rao|Vikram R|VR|0000-0002-6389-2638']
D000293:Adolescent D000328:Adult D002648:Child D015331:Cohort Studies D000069279:Drug Resistant Epilepsy D004599:Electric Stimulation Therapy D004567:Electrodes, Implanted D004828:Epilepsies, Partial D005260:Female D006801:Humans D008297:Male D019579:Neocortex D012189:Retrospective Studies D055815:Young Adult
responsive neurostimulation RNS System regional neocortical seizures drug-resistant epilepsy