256 adults with medically intractable focal onset seizures localized to 1 or 2 seizure foci were treated in the pivotal (N=191) or feasibility (N=65) studies and 230 transitioned into the LTT study. Efficacy assessments included median % change in seizure frequency. Safety was assessed by reporting of 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/month. Total follow-up was 9 years with 1895 patient implant years. The median % reduction reached 75% at the end of year 9 (n=168). In addition, 30% of subjects experienced ≥ one period of ≥ 6-months without seizures and 19% experienced ≥12 months without seizures. A LOCF analysis showed a median % reduction of 67.2% (IQR: 23 to 94.5%) with 33% of patients having a 90% or greater reduction in seizures in their most recent 3 months. Risk for infection was 3.7% per procedure, and all but one infection was soft tissue only. There were 16 deaths; 2 due to suicide, 1 each due to status epilepticus, herpes encephalitis, sepsis, lung/colon cancer, and lymphoma, and 4 due to definite, 2 due to probable, and 3 due to possible SUDEP.