title: Prospective long-term study of vagus nerve stimulation for the treatment of refractory seizures.
abstract: OBJECTIVE
  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.
authors.affiliation: Olive View/UCLA Medical Center and UCLA Department of Neurology, Los Angeles, California 91342, USA. cmd@ucla.edu
authors.forename: C M
authors.initials: CM
authors.lastname: DeGiorgio
authors.forename: S C
authors.initials: SC
authors.lastname: Schachter
authors.forename: A
authors.initials: A
authors.lastname: Handforth
authors.forename: M
authors.initials: M
authors.lastname: Salinsky
authors.forename: J
authors.initials: J
authors.lastname: Thompson
authors.forename: B
authors.initials: B
authors.lastname: Uthman
authors.forename: R
authors.initials: R
authors.lastname: Reed
authors.forename: S
authors.initials: S
authors.lastname: Collins
authors.forename: E
authors.initials: E
authors.lastname: Tecoma
authors.forename: G L
authors.initials: GL
authors.lastname: Morris
authors.forename: B
authors.initials: B
authors.lastname: Vaughn
authors.forename: D K
authors.initials: DK
authors.lastname: Naritoku
authors.forename: T
authors.initials: T
authors.lastname: Henry
authors.forename: D
authors.initials: D
authors.lastname: Labar
authors.forename: R
authors.initials: R
authors.lastname: Gilmartin
authors.forename: D
authors.initials: D
authors.lastname: Labiner
authors.forename: I
authors.initials: I
authors.lastname: Osorio
authors.forename: R
authors.initials: R
authors.lastname: Ristanovic
authors.forename: J
authors.initials: J
authors.lastname: Jones
authors.forename: J
authors.initials: J
authors.lastname: Murphy
authors.forename: G
authors.initials: G
authors.lastname: Ney
authors.forename: J
authors.initials: J
authors.lastname: Wheless
authors.forename: P
authors.initials: P
authors.lastname: Lewis
authors.forename: C
authors.initials: C
authors.lastname: Heck
mesh_terms: D004599:Electric Stimulation Therapy; D004827:Epilepsy / Q000628:therapy*; D006801:Humans; D008137:Longitudinal Studies; D011446:Prospective Studies; D016896:Treatment Outcome; D014630:Vagus Nerve / Q000502:physiology*