title: Complications of vagal nerve stimulation for drug-resistant epilepsy: a single center longitudinal study of 143 patients.
abstract: OBJECTIVE
  To longitudinally study surgical and hardware complications to vagal nerve stimulation (VNS) treatment in patients with drug-resistant epilepsy.
  
  
  METHODS
  In a longitudinal retrospective study, we analyzed surgical and hardware complications in 143 patients (81 men and 62 women) who between 1994 and 2010 underwent implantation of a VNS-device for drug-resistant epilepsy. The mean follow-up time was 62 ± 46 months and the total number of patient years 738.
  
  
  RESULTS
  251 procedures were performed on 143 patients. 16.8% of the patients were afflicted by complications related to surgery and 16.8% suffered from hardware malfunctions. Surgical complications were: superficial infection in 3.5%, deep infection needing explantation in 3.5%, vocal cord palsy in 5.6%, which persisted in at least 0.7% for over one year, and other complications in 5.6%. Hardware-related complications were: lead fracture in 11.9% of patients, disconnection in 2.8%, spontaneous turn-off in 1.4% and stimulator malfunction in 1.4%. We noted a tendency to different survival times between the two most commonly used lead models as well as a tendency to increased infection rate with increasing number of stimulator replacements.
  
  
  CONCLUSIONS
  In this series we report on surgical and hardware complications from our 16 years of experience with VNS treatment. Infection following insertion of the VNS device and vocal cord palsy due to damage to the vagus nerve are the most serious complications related to the surgery. Avoiding unnecessary reoperations in order to reduce the appearances of these complications are of great importance. It is therefore essential to minimize technical malfunctions that will lead to additional surgery. Further studies are needed to evaluate the possible superiority of the modified leads.
authors.affiliation: Department of Pharmacology and Clinical Neuroscience, Umeå University, Section of Neurosurgery, Umeå University Hospital, Umeå, Sweden. Electronic address: hanneskahlow@hotmail.com.
authors.forename: Hannes
authors.initials: H
authors.lastname: Kahlow
authors.forename: Magnus
authors.initials: M
authors.lastname: Olivecrona
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000927:Anticonvulsants / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D004827:Epilepsy / Q000188:drug therapy / Q000628:therapy*; D004868:Equipment Failure; D005260:Female; D006801:Humans; D007239:Infections / Q000209:etiology*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D019233:Retreatment; D012189:Retrospective Studies; D016896:Treatment Outcome; D055536:Vagus Nerve Stimulation / Q000009:adverse effects*; D014826:Vocal Cord Paralysis / Q000209:etiology*
chemical_list: D000927:Anticonvulsants
keywords: Complication; Epilepsy; Vagal nerve stimulation