Long-Term Seizure Reduction With Responsive Neurostimulation
At the American Epilepsy Society Annual Meeting in New Orleans, LA, results were announced from a 9-year prospective study of treatment with responsive neurostimulation (RNS) (RNS System; NeuroPace, Mountain View, CA) for patients with medically refractory epilepsy. For 256 patients treated, a median 75% reduction in seizures was achieved overall at 9 years. The benchmark 50% reduction in seizure frequency was also achieved by 75% of patients, and approximately 33% of patients achieved a 90% or more reduction in seizures. Freedom from seizure for periods of 6 months or longer was achieved by 28% of patients. Quality of life measures including memory and cognition improved over the course of the study.
Delivered via a surgically implanted electrode at the brain surface or in deep brain structures, RNS provides both ongoing EEG measurement and delivery of neurostimulation that can be adjusted in response to ictal activity that correlates with seizure. The system also stores some EEG data that can be transferred to a laptop, allowing interpretation by the neurologist and subsequent adjustment of the system. RNS is most effective when used for patients who have 1 to 2 apparently isolated seizure foci that correspond to a well-localized onset zone.
“For patients who have met the criteria of medically intractable epilepsy, medications don’t really offer continuing medical benefits. Therefore, it is important to consider surgical options when the data are aligned well and it occurs in an area of the brain that can be safely resected and will not result in significant cognitive impairment,” noted Dr. Dileep Nair, a paid consultant to NeuroPace, principal investigator of the study and section head of adult epilepsy at Cleveland Clinic’s Neurological Institute. “When those conditions cannot be met, we now have a new mode of therapy that is very different from medical and surgical options: no tissue needs to be removed, there seems to be a therapeutic improvement over time, and the benefit is known very quickly. If medicines fail, we have a new option.”