title: Long term effect of vagus nerve stimulation in pediatric intractable epilepsy: an extended follow-up.
abstract: OBJECTIVE
  Over the past two decades, vagus nerve stimulation (VNS) has become an accepted and viable treatment modality for intractable epilepsy both in children and adults. Earlier studies have demonstrated short-term seizure outcomes, usually for up to 5 years; so far, none have reported an extended outcome in children. We aimed to assess long term seizure outcome in children with intractable epilepsy for more than 5 years.
  
  
  METHODS
  We identified patients who had VNS implantation for treatment of intractable epilepsy from March 2000 to March 2015 at our Epilepsy Center and collected data including demographic, age at epilepsy onset and VNS implantation, duration of epilepsy, seizure type, number of antiepilepsy drugs (AEDs), and monthly seizure frequency before VNS implantation and at the last clinic visit. Phone surveys were conducted with patients without recent clinic follow-up.
  
  
  RESULTS
  Fifty-six patients (aged 4-17 at the time of implant) are the subjects of the study. Seizure reduction of >50 % was achieved in 9.8 % (6th month), 24 % (2nd year), 46.4 % (3rd year), and 54 %(5th year), and overall 35 (62.5 %) of the 56 subjects had a greater than 50 % reduction in seizure frequency at the last follow-up. Eleven patients became seizure free. The results, once obtained, were maintained steadily or even improved over time without any loss of efficacy during the follow-up. The only parameter, significantly related with clinical response, was age at seizure onset. The most frequent adverse events were hoarseness, cough, sore throat, and anorexia, experienced by 13 patients. Two patients had local wound infections and lead to the removal of the stimulator. An improvement in alertness, attention, and psychomotor activity, independent of the efficacy of vagal nerve stimulation, was observed in 8 patients.
  
  
  CONCLUSIONS
  To our knowledge, this is the first pediatric study evaluating seizure outcome over more than 5 years of follow-up, and demonstrates a favorable seizure outcome of >50 % seizure frequency in 62.5 % of patients and seizure freedom in 11 patients. It is well tolerated over an extended period of time.
authors.affiliation: Pediatric Neurology Department, Gazi University Faculty of Medicine, 10th Floor Besevler, Ankara, Turkey.
authors.forename: Ayse
authors.initials: A
authors.lastname: Serdaroglu
authors.affiliation: Pediatric Neurology Department, Gazi University Faculty of Medicine, 10th Floor Besevler, Ankara, Turkey. petekarhan@yahoo.com.tr.
authors.forename: Ebru
authors.initials: E
authors.lastname: Arhan
authors.affiliation: Department of Neurosurgery, Gazi University Faculty of Medicine, 10th Floor Besevler, Ankara, Turkey.
authors.forename: Gökhan
authors.initials: G
authors.lastname: Kurt
authors.affiliation: Department of Neurosurgery, Ankara University Faculty of Medicine, Ankara, Turkey.
authors.forename: Atilla
authors.initials: A
authors.lastname: Erdem
authors.affiliation: Department of Neurosurgery, Gazi University Faculty of Medicine, 10th Floor Besevler, Ankara, Turkey.
authors.forename: Tugba
authors.initials: T
authors.lastname: Hirfanoglu
authors.affiliation: Pediatric Neurology Department, Gazi University Faculty of Medicine, 10th Floor Besevler, Ankara, Turkey.
authors.forename: Kursad
authors.initials: K
authors.lastname: Aydin
authors.affiliation: Department of Neurology, Gazi University Faculty of Medicine, 10th Floor Besevler, Ankara, Turkey.
authors.forename: Erhan
authors.initials: E
authors.lastname: Bilir
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D000069279:Drug Resistant Epilepsy / Q000000981:diagnostic imaging / Q000628:therapy*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D012189:Retrospective Studies; D016896:Treatment Outcome; D055536:Vagus Nerve Stimulation / Q000379:methods*
keywords: Intractable epilepsy; Pediatrics; Vagal nerve stimulation