Comparison of Responsive Neurostimulation System Efficacy Between Different Electrographic Seizure Onset Patterns (1255)

Objective: Define predominant seizure onset patterns (SOP) on electrocorticography recordings (ECoGs) of Responsive Neurostimulation System (RNS)–implanted patients and determine their impact on response to neurostimulation. Background: About 1/3 of epilepsy patients are refractory to antiepileptic drugs alone. For those with focal onset seizures, RNS may represent a beneficial adjunctive therapy. This device can detect and interrupt seizure-like activity with focal stimulation. Although seizure reduction in RNS patients seems unrelated to prior interventions or location of leads, the role of SOP in responsiveness to RNS remains unclear. Design/Methods: Based on diary reports or magnet swipes, we selected an average of 11 ECoGs per patient from 24 RNS-implanted patients. The SOP classification was 1b: low voltage fast activity 50% improvement over baseline seizure frequency prior to RNS. We then compared response rates for each predominant SOP. Results: 270 seizure-associated ECoGs were analyzed. Overall, pattern 1g was the most frequent (102; 37.78%) followed by pattern 3 (48; 17.8%). Thirteen out of 24 patients (54.2%) responded to RNS, with 1g as their predominant pattern (50%). Among non-responders, pattern 1g (45.5%) was also the most frequently seen. No clear differences were seen in responses between SOP; there were eight responders out of 13 patients with predominant pattern 1g vs. five responders out of 11 patients with other patterns (χ2 = 0.62). Conclusions: Gamma activity was the predominant electrographic SOP. Based on these preliminary results, RNS efficacy appears independent of the predominant SOP. Disclosure: Dr. Henriquez-Rojas has nothing to disclose. Dr. Torabi has nothing to disclose. Dr. Farooque has nothing to disclose. Dr. Hirsch has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Adamas, Aquestive, Ceribell, Eisai, Monteris, Marinus, Neuropace, and UCB.Dr. Duckrow has nothing to disclose. Dr. Herlopian has nothing to disclose. Dr. Spencer has nothing to disclose. Dr. Gerrard has nothing to disclose. Dr. Quraishi has nothing to disclose.