Seizure and cognitive outcomes of cortical long bursting responsive neurostimulation in intractable focal epilepsy

Responsive Neurostimulation (RNS) is an established therapy for drug-resistant epilepsies (DRE), yet conventional high-frequency stimulation delivered in short bursts (SB; 100 ms) may fail to achieve significant seizure reduction. This retrospective study evaluated the efficacy of cortical high-frequency long-burst (LB; 5000 ms) RNS therapy in 13 DRE patients who experienced less than a 50 % reduction in seizures with SB therapy. After initiating LB therapy, 55 % of patients achieved a seizure reduction of more than 50 %, with a median follow-up of 13 months. Although the number of stimulation therapies delivered per day did not significantly differ between the SB and LB paradigms, the LB RNS delivered a substantially higher charge per hour (mean 18 mC/hr vs. 0.7 mC/hr) to the epileptogenic cortex. Importantly, despite the increased charge, no cognitive decline was observed, likely due to the precise timing of the stimulation in response to epileptiform activity. These findings suggest that LB RNS may be a viable alternative for patients who do not respond to conventional RNS therapy, offering improved seizure control without compromising cognitive function. However, the increased charge raises concerns about battery life, emphasizing the need for further research on different stimulation frequencies in LB RNS. This study highlights the potential of tailored stimulation paradigms to optimize outcomes in drug-resistant epilepsy.