Programming parameters affecting seizure reduction in responsive neurostimulation patients at a pediatric center

Responsive neurostimulation (RNS) is an effective treatment for drug-resistant epilepsy, but optimal programming strategies remain undefined in pediatric populations. This study investigates the effect of programming parameter differences on time to > 50% seizure reduction. We aimed to determine the charge density at time of 50% seizure reduction response, based on target (cortical v. thalamic).

A retrospective review of 39 pediatric and young adult epilepsy patients implanted with the RNS system at a single center was performed. Re-programming proceeded based on a standardized protocol, with programming parameters differing depending on cortical vs. thalamic targets. Standard cortical stimulation included 200 Hz, short burst (100-500 ms), high charge (2-4 uC) therapy. Standard thalamic stimulation included 5 Hz, long burst (5 s), low charge (1-2 uC) therapy. The primary outcome was time from implantation to achieving > 50% seizure reduction.

Within 39 patients (25 cortical and 14 thalamic targets), 33 (84.6%) achieved > 50% seizure reduction. At time of seizure reduction, median charge for cortical leads was 1.0 μC/cm²; and for thalamic leads 0.65 μC/cm². Thalamic leads seemed to be associated with a shorter time to seizure response (HR: 7.13, p = 0.038), despite lower charge densities at event.

Divergent programming strategies in cortical and thalamic RNS targets result in similar efficacy. Both were effective across differing seizure etiologies and types. These findings support the use of structured, individualized programming protocols in pediatric epilepsy care.