Authors :
Presenting Author: Patricia Dugan, MD – NYU Grossman School of Medicine
Taneeta Ganguly, MD – University of Pennsylvania
Angela Peters, MD – University of Utah
Martha Morrell, MD – NeuroPace
Rationale: Generalized tonic clonic (GTC) seizures are of particular concern in patients with antiseizure medication (ASM)-resistant focal epilepsy. Compared to nonconvulsive seizures, GTCs carry a greater risk for injury and sudden unexpected death in epilepsy (SUDEP). Although the therapeutic benefit of an antiseizure treatment is generally assessed as reduction in overall seizure frequency, an additional clinically relevant assessment is reduction in GTCs. The RNS® System Post Approval study is an FDA-required 5-year prospective open label post-approval study to assess real-world effectiveness and safety in persons with ASM-resistant focal epilepsy (
NCT02403843). This analysis specifically considers reduction in GTC frequency at 1, 2, and 3 years of RNS® System treatment.
Methods:
Participants were adults (18+) with drug-resistant focal onset epilepsy who met the approved RNS System indication. All participants provided a retrospective 3-month pre-implant seizure rate and then maintained a seizure diary from implantation of the RNS System neurostimulator and leads throughout study participation. Participants with GTCs during their pre-treatment baseline were selected for an assessment of change in GTC frequency at 12, 24, and 36 months of treatment. The 3 months of baseline seizure data were compared to the 3 months preceding each of the timepoints.
Results:
324 patients were treated with the RNS System across 32 U.S. epilepsy centers. One hundred thirty-three had GTCs at baseline, and 89 of these patients (67%) completed 36 months of follow-up. The median 3-month baseline GTC count was 3.
The median percent reduction in frequency of GTCs was 100% at each of the 12-, 24- and 36-month post-implant timepoints (p< 0.001 at 36 months compared to baseline; Wilcoxon Signed Rank). Over the 36-month follow up, 86.55% of participants who had at least 6 months of data had no GTCs for 6 months or more, while 70.69% of participants who had at least 12 months of data had no GTCs for 12 months or more. The change in GTCs was similar for patients with mesial temporal, neocortical, or both mesial temporal and neocortical onsets, and for patients with one or two seizure onset zones.