title: Long-term results of vagal nerve stimulation for adults with medication-resistant epilepsy who have been on unchanged antiepileptic medication.
abstract: OBJECTIVE
  Several studies suggest that vagal nerve stimulation (VNS) is an effective treatment for medication-resistant epileptic patients, although patients' medication was usually modified during the assessment period. The purpose of this prospective study was to evaluate the long-term effects of VNS, at 18 months of follow-up, on epileptic patients who have been on unchanged antiepileptic medication.
  
  
  METHODS
  Forty-three patients underwent a complete epilepsy preoperative evaluation protocol, and were selected for VNS implantation. After surgery, patients were evaluated on a monthly basis, increasing stimulation 0.25mA at each visit, up to 2.5mA. Medication was unchanged for at least 18 months since the stimulation was started. The outcome was analysed in relation to patients' clinical features, stimulation parameters, epilepsy type, magnetic resonance imaging (MRI) results, and history of prior brain surgery.
  
  
  RESULTS
  Of the 43 operated patients, 63% had a similar or greater than 50% reduction in their seizure frequency. Differences in the responder rate according to stimulation intensity, age at onset of epilepsy, duration of epilepsy before surgery, previous epilepsy surgery and seizure type, did not reach statistical significance. Most side effects were well tolerated.
  
  
  CONCLUSIONS
  62.8% of our series of 43 medication-resistant epileptic patients experienced a significant long-term seizure reduction after VNS, even in a situation of on unchanged medical therapy. Patient characteristics predictive of VNS responsiveness remain subject to investigation. Controlled studies with larger sample sizes, on VNS for patients with medication-resistant epilepsy on unchanged medication, are necessary to confirm VNS efficacy for drug-resistant epilepsy, and to identify predictive factors.
authors.affiliation: Division of Neurosurgery, Department of Surgery, University Hospital La Princesa, Universidad Autónoma, Madrid, Spain.
authors.forename: Eduardo
authors.initials: E
authors.lastname: García-Navarrete
authors.forename: Cristina V
authors.initials: CV
authors.lastname: Torres
authors.forename: Isabel
authors.initials: I
authors.lastname: Gallego
authors.forename: Marta
authors.initials: M
authors.lastname: Navas
authors.forename: Jesús
authors.initials: J
authors.lastname: Pastor
authors.forename: R G
authors.initials: RG
authors.lastname: Sola
mesh_terms: D000328:Adult; D000927:Anticonvulsants / Q000009:adverse effects; D004827:Epilepsy / Q000145:classification / Q000628:therapy*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome; D055536:Vagus Nerve Stimulation / Q000379:methods*; D055815:Young Adult
chemical_list: D000927:Anticonvulsants