LONG-TERM SAFETY AND EFFICACY OF RESPONSIVE BRAIN STIMULATION IN ADULTS WITH MEDICALLY INTRACTABLE PARTIAL ONSET SEIZURES
Authors: M. Morrell, F. Sun, D. King-Stephens, A. Murro, G. L. Barkley, R. Gwinn, K. Noe, G. Bergey, C. Heck, A. Massey, R. Duckrow, R. Wharen, M. Smith, C. Bazil, P. Van Ness, D. Nair, B. Jobst, V. Salanova, A. Cole, G. Worrell, J. Edwards, D. Spencer, C. Skidmor
The RNS® System (NeuroPace, Inc.) is an investigational device that provides responsive cortical stimulation. Efficacy and safety of the RNS System as an adjunctive treatment for adults with partial onset seizures was demonstrated in a 2 year multicenter randomized double blinded controlled pivotal study. Additional safety data was collected in an earlier 2 year feasibility study. A multi-center prospective open-label 7 year long-term treatment study is being conducted for subject who completed the pivotal or feasibility studies in order to accumulate a total of 9 years of prospective data on safety and effectiveness.
Subjects were adults with medically intractable partial onset seizures localized to 1 or 2 seizure foci (N=256; 191 implanted in the pivotal study and 65 implanted in the feasibility study). Assessments included seizure frequency % change and responder rate (RR, % of subjects with a 50% or greater reduction in seizures), and safety as assessed by adverse events.
Mean age was 34.0 years, mean epilepsy duration was 19.6 years, mean number of AEDs was 2.9, and median seizure frequency was 10.2 seizures/28 days. As of 11/1/2012, the median follow-up was 4.5 years with 1200 patient implant years. The median % seizure reduction and RR for each 3-month period after 6 months post implant (all subjects in open label protocol) are presented in Figure 1. The median % reduction was 38.9% at one year and 51.1% at two years. 20% of subjects were seizure free for ≥ 6-months. There were no unanticipated device-related serious adverse events (SAEs), and the overall rate of device related AEs declined with time. The SAE event rate related to hemorrhage was 0.010/implant year and for infection was 0.023/implant year. The majority of the events occurred in the 1st year after implant. There were 11 deaths; 2 due to suicide, one each due to status epilepticus and lymphoma, and 7 due to SUDEP (2 of these patients were not being treated with responsive stimulation). The SUDEP rate was 4.5/1000 patient stimulation years.
The seizure reduction in subjects treated with the RNS System improved over the first 2 years and was sustained in the following years. Treatment remained safe over time. This experience supports the long-term effectiveness and safety of treatment with the RNS System.
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