Prospectively evaluate safety and efficacy of brain-responsive neurostimulation in adults with medically intractable focal onset seizures (FOS) over 9 years..
Adults treated with brain-responsive neurostimulation within 2 year feasibility or randomized controlled trials enrolled into a long-term prospective open label trial (LTT) to assess safety, efficacy, and quality of life (QOL) over an additional 7 years. Safety was assessed as adverse events (AEs), efficacy as median percent change in seizure frequency and responder rate, and QOL using the quality of life in epilepsy (QOLIE-89) inventory.
Results. 230 of 256 patients treated in the initial trials participated in the LTT. At 9 years, the median percent reduction in seizure frequency was 75% (p<0.0001; Wilcoxon Signed Rank), responder rate was 73%, and 35% had a ≥90% reduction in seizure frequency. 18.4% (47/256) experienced ≥1 year of seizure freedom with 62% (29/47) seizure free at last follow-up and an average seizure-free period of 3.2 years (range: 1.04 – 9.6 years).
Overall QOL, epilepsy-targeted and cognitive domains of QOLIE-89 remained significantly improved (p<0.05). There were no serious AEs related to stimulation and the sudden unexplained death in epilepsy (SUDEP) rate was significantly lower than predefined comparators (p<0.05; one-tailed Chi Square).
Conclusions. Adjunctive brain-responsive neurostimulation provides significant and sustained reductions in the frequency of FOS with improved QOL. Stimulation was well tolerated, implant related AEs were typical of other neurostimulation devices, and SUDEP rates were low.