Reduction of generalized tonic-clonic seizures following vagus nerve stimulation therapy: CORE-VNS Study 24-month follow-up.

Abstract

Objective: Generalized tonic-clonic seizures (GTCS) are considered to be among the most devastating seizures due to increased health risks. Use of device-based therapies, such as vagus nerve stimulation (VNS), is common for those resistant to antiseizure medications and important for those in whom resective surgery is not feasible. Our objective is to investigate whether adjunctive VNS can reduce the frequency of GTCS.

Methods: Participants were enrolled in an international, multicenter, prospective observational study (CORE-VNS) on seizure and nonseizure outcomes following the implantation of VNS. Participants with GTCS at baseline were selected for analysis. Baseline seizure frequency data and patient-reported outcome measures were collected at 3, 6, 12, 24, and 36 months. This interim analysis compared baseline data to VNS therapy outcomes through 24 months.

Results: A total of 115 participants met the inclusion criteria. Following 12 months of VNS, participants experienced a median GTCS reduction of 73.9%, with 37% of participants reporting seizure freedom from GTCS for the 3 months prior to the 12-month follow-up. This outcome remained stable at 24 months, with a median GTCS reduction of 77% and 42.6% of participants reporting seizure freedom for the 3 months prior to the 24-month visit. After 12 months of VNS, the number of participants reporting the postictal severity of their most debilitating seizure as "severe" or "very severe" dropped from 52.8% to 25.3% (21/83). After 24 months of VNS, the percentage of participants reporting these levels of postictal severity was 26.3% (20/76). The participants' drug load did not change significantly during the follow-up. Adverse events were typical of those previously documented in patients with drug-resistant epilepsy (DRE) using VNS.

Significance: Adjunctive VNS therapy was effective in reducing GTCS frequency in study participants. The sustained and consistent nature of the response further supports VNS as a long-term effective therapy in patients with DRE who have GTCS.