Brain responsive neurostimulation device safety and effectiveness in patients with drug-resistant autoimmune-associated epilepsy

Purpose: This study examines the safety and effectiveness of brain-responsive neurostimulation (RNS System) therapy in patients with refractory autoimmune-associated epilepsy (AAE). Methods: We retrospectively reviewed 85 medical records of patients who were treated with the RNS System at the three Mayo Clinic sites to identify patients with AAE. We collected clinical data including demographics, epilepsy history, prior evaluations and treatment, RNS implantation and lead information, long term ambulatory electrocorticography (ECoG) data, and patient-reported seizure details. Inclusion criteria included: (1) confirmed neural antibodies, or absent/negative autoimmune panel with Antibody Prevalence in Epilepsy (APE2) score ≥ 4 and (2) at least 6 months of follow up after RNS implantation. The primary outcomes measured were patient-reported seizure frequencies at last follow-up as compared to baseline, ECoG long-episode frequencies, and adverse events following RNS implantation. Results: Of the 85 patients reviewed, nine (11 %) met the inclusion criteria. Three patients had GAD65 antibodies (mean serum titer = 816 ug/dl), one had Rasmussen's encephalitis (biopsy proven), and five had absent/negative neuronal antibody panel but APE scores were ≥ 4. Six out of nine patients (67 %) reported improvement in clinical seizure frequency, all reported improvements in seizure duration and intensity. Four of 9 patients (44 %) showed trends of decreasing frequency of prolonged periods of epileptiform activity over time. One patient (11 %) developed a superficial wound infection at the implant site. Conclusion: The findings from our study suggest that adjunctive treatment with the RNS System may be a safe option for patients with refractory AAE.