title: Vagus nerve stimulation therapy: 5-year or greater outcome at a university-based epilepsy center.
abstract: OBJECTIVE
  This retrospective study documented long-term outcome of patients receiving vagus nerve stimulation (VNS) therapy for pharmacoresistant epilepsy.
  
  
  METHODS
  Medical charts of 28 patients implanted for 5 years or longer were reviewed for changes in seizure frequency after 1 year of VNS therapy and at follow up, which ranged from 5 to 7 years. Numbers of antiepileptic drugs (AEDs) taken by the patients were also computed at 1 year and follow up. One patient had died and one had discontinued VNS therapy; data were available for 26 patients.
  
  
  RESULTS
  The median percent change in seizure frequency from baseline increased from -28% (P = 0.0053, Wilcoxon signed-rank test) at 12 months to -72% (P < 0.0001) at follow up. Some patients whose seizure frequency was not reduced during the initial 12 months of VNS therapy did experience reductions in seizure frequency during the follow-up period.
  
  
  CONCLUSIONS
  In this retrospective study, the effectiveness of VNS therapy increased over time. Physicians should be aware that response to VNS therapy may be delayed for some patients.
authors.affiliation: Department of Neurology, Medical College of Wisconsin, 9200 W. Wisconsin Avenue, Milwaukee, WI 53226, USA. mspanaki@mcw.edu
authors.forename: Marianna V
authors.initials: MV
authors.lastname: Spanaki
authors.forename: Linda S
authors.initials: LS
authors.lastname: Allen
authors.forename: Wade M
authors.initials: WM
authors.lastname: Mueller
authors.forename: George L
authors.initials: GL
authors.lastname: Morris
mesh_terms: D000293:Adolescent; D000328:Adult; D000553:Ambulatory Care; D000927:Anticonvulsants / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D004599:Electric Stimulation Therapy / Q000379:methods*; D004567:Electrodes, Implanted; D004827:Epilepsy / Q000188:drug therapy / Q000628:therapy*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D017063:Outcome Assessment, Health Care; D012189:Retrospective Studies; D014495:Universities; D014630:Vagus Nerve / Q000502:physiology*
chemical_list: D000927:Anticonvulsants