title: Vagus nerve stimulation therapy for patients with persistent seizures after epilepsy surgery.
abstract: BACKGROUND
  This study reports the effectiveness of vagus nerve stimulation (VNS) among patients who failed cranial surgery for intractable epilepsy.
  
  
  METHODS
  Data were obtained from the Cyberonics VNS therapy patient outcome registry. The integrity of the systems for collecting and processing registry data was authenticated by an independent auditing agency.
  
  
  RESULTS
  Two nonconsecutive cohorts were compared: patients who had had prior cranial surgery (CS group, n = 921) and those who had not (non-CS group, n = 3,822). For the CS group, the median reduction in seizure frequency was 42.5% after 3 months of VNS therapy, 42.9% at 6 months, 45.7% at 12 months, 52.0% at 18 months and 50.5% at 24 months. For the non-CS group, analogous rates were 47.0, 52.9, 60.0, 62.7 and 66.7%, respectively.
  
  
  CONCLUSIONS
  The effectiveness of VNS is maintained during prolonged stimulation. Patients who failed prior cranial surgery did not respond quite as favorably as all other patients receiving VNS therapy.
authors.affiliation: Department of Neurosurgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA. amar@aya.yale.edu
authors.forename: Arun Paul
authors.initials: AP
authors.lastname: Amar
authors.forename: Michael L J
authors.initials: ML
authors.lastname: Apuzzo
mesh_terms: D004599:Electric Stimulation Therapy; D004827:Epilepsy / Q000601:surgery / Q000628:therapy*; D006801:Humans; D012008:Recurrence; D012042:Registries; D013702:Temporal Lobe / Q000601:surgery; D016896:Treatment Outcome; D014630:Vagus Nerve / Q000502:physiology*