Prospective long-term study of vagus nerve stimulation for the treatment of refractory seizures

Epilepsia. 2000 Sep;41(9):1195-200. doi: 10.1111/j.1528-1157.2000.tb00325.x.


Purpose: To determine the long-term efficacy of vagus nerve stimulation (VNS) for refractory seizures. VNS is a new treatment for refractory epilepsy. Two short-term double-blind trials have demonstrated its safety and efficacy, and one long-term study in 114 patients has demonstrated a cumulative improvement in efficacy at 1 year. We report the largest prospective long-term study of VNS to date.

Methods: Patients with six or more complex partial or generalized tonic-clonic seizures enrolled in the pivotal EO5 study were prospectively evaluated for 12 months. The primary outcome variable was the percentage reduction in total seizure frequency at 3 and 12 months after completion of the acute EO5 trial, compared with the preimplantation baseline. Subjects originally randomized to low stimulation (active-control group) were crossed over to therapeutic stimulation settings for the first time. Subjects initially randomized to high settings were maintained on high settings throughout the 12-month study.

Results: The median reduction at 12 months after completion of the initial double-blind study was 45%. At 12 months, 35% of 195 subjects had a >50% reduction in seizures, and 20% of 195 had a >75% reduction in seizures.

Conclusions: The efficacy of VNS improves during 12 months, and many subjects sustain >75% reductions in seizures.

Publication types

  • Clinical Trial
  • Controlled Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Electric Stimulation Therapy*
  • Epilepsy / therapy*
  • Humans
  • Longitudinal Studies
  • Prospective Studies
  • Treatment Outcome
  • Vagus Nerve / physiology*