Responsive stimulation of the thalamus for idiopathic generalized epilepsy: Results of the randomized controlled NAUTILUS trial through 18 months

OBJECTIVE: This study was undertaken to evaluate the safety and effectiveness of responsive thalamic stimulation as adjunctive therapy for drug-resistant idiopathic generalized epilepsy (IGE) with generalized tonic-clonic seizures (GTCSs). METHODS: NAUTILUS is a prospective, multicenter, single-blind, randomized sham-controlled pivotal trial. Patients were ≥12 years of age with drug-resistant IGE and ≥2 GTCSs over a 3-month baseline. Bilateral depth leads were targeted to the centromedian thalamus. One month later, patients were randomized to Active (responsive stimulation, n = 44) or Sham (no stimulation, n = 43). The effectiveness evaluation period (EEP) began 3 months postimplant through 1 year. After a second GTCS in the EEP, patients transitioned to open-label active stimulation. The primary safety endpoint was the serious adverse device-related event (SADE) rate at 84 days postimplant. The primary effectiveness endpoint was time-to-second-GTCS during the EEP. Additional endpoints included median percent change in days with any generalized seizure, GTCS frequency, and responder rate (RR). RESULTS: Eighty-seven patients were implanted across 23 US centers. The SADE rate was significantly below the performance goal (6.9%, p < .0001), with no adverse effects on cognition, mood, or sleep. The prespecified primary effectiveness endpoint was not significant. However, a post hoc mixed-effects model considering all EEP days demonstrated greater GTCS reduction in the originally randomized Active group (61%) compared to patients originally randomized to Sham (49%, p = .030). Eighteen-month outcomes included 76.8% median GTCS reduction, 62.5% RR, 40% GTCS-free at that timepoint, and 77.8% median reduction in days with any generalized seizure. More than 90% of patients and 86% of physicians reported improvement on Global Impression of Change scales. SIGNIFICANCE: NAUTILUS is the first randomized controlled neuromodulation trial in IGE. Responsive thalamic stimulation provided a clinically meaningful and durable reduction in seizures with an acceptable safety profile, offering a much-needed option for drug-resistant IGE.