Neurostimulation demonstrates long-term safety, efficacy for focal-onset seizures

Adjunctive brain-responsive neurostimulation results in significant and sustained decreases in the frequency of focal-onset seizures while also improving quality of life, according to study data published in Neurology.

The long-term, prospective, open-label trial that examined the safety and efficacy of brain-responsive neurostimulation in adults with medically intractable focal-onset seizures also demonstrated that the stimulation was well tolerated. Related adverse events were similar to other neurostimulation devices and rates of sudden unexplained death in epilepsy (SUDEP) were low.

Approximately 30% to 40% of epilepsy cases are refractory to medications, according to Dileep R. Nair, MD, of the Cleveland Clinic, and colleagues. Resective or ablative procedures offer the best chance for freedom from seizures for these patients, according to the researchers, but “are not an option” for many patients because of the potential neurological risk and insufficient probability of benefit.

“Neuromodulation approaches including vagus nerve stimulation, deep brain stimulation and brain-responsive neurostimulation (RNS System, NeuroPace, Inc.) have been demonstrated to be safe and effective treatments to reduce seizure frequency for these patients,” Nair and colleagues wrote. “In contrast to [deep brain stimulation], brain-responsive neurostimulation delivers stimulation only in response to changes in ongoing neural activity at the seizure focus. While this approach requires the identification of the seizure focus, it limits the amount of stimulation delivered per day.”

The researchers enrolled adults who received treatment with brain-responsive neurostimulation within 2-year feasibility or randomized controlled trials in a long-term, prospective, open-label trail to evaluate safety, efficacy and quality of life over 7 more years. They used adverse events to measure safety, median percent change in seizure frequency and responder rate to measure efficacy and the Quality of Life in Epilepsy (QOLIE-89) inventory to measure quality of life.

The long-term analysis included 230 of 256 patients from in the original trials.

The 9-year results demonstrated a median percent reduction in seizure frequency of 75% (P < .0001), a responder rate of 73% and a 90% or greater reduction in seizure frequency of 35%. Further, 18.4% of patients experienced at least 1 year free of seizures, with 62% seizure-free at last follow-up and an average seizure-free period of 3.2 years (range, 1.04-9.6 years). Participants also demonstrated consistent, significant improvement in quality of life, epilepsy-targeted and cognitive domains of QOLIE-89 (P < .05).

Nair and colleagues reported no serious adverse events related to stimulation. The study findings also demonstrated a SUDEP rate that was significantly lower than predefined comparators (P < .05).

“As with all other epilepsy therapies, there was a range of patient responses,” Nair and colleagues wrote. “However, this study provides substantial evidence that adjunctive treatment with brain-responsive neurostimulation is safe, and provides persons with medically intractable focal epilepsy an opportunity for significant and sustained reductions in disabling seizures with enduring improvements in quality of life, and SUDEP rates that were lower than anticipated for similar patient populations. The safety of the surgical procedure and the implanted device compares favorably to other brain stimulation devices used for treatment of movement disorders and epilepsy.”