An interictal EEG can predict the outcome of vagus nerve stimulation therapy for children with intractable epilepsy

This study aimed to evaluate the long-term efficacy of vagus nerve stimulation (VNS) in children and adolescents with intractable epilepsy and identify predictive factors for responsiveness to VNS. Medical records of pediatric patients who underwent VNS implantation at two Korean tertiary centers were reviewed. At 0.5, 1, 3, and 5 years post-VNS implantation, the frequency of the most disabling seizures in each patient was assessed. Responders were defined as showing an overall 50 % reduction from baseline seizure frequency during follow-up. The clinical characteristics of responders and non-responders were compared. Among 58 patients, approximately half (29/58) were responders. The mean age at implantation was 10.9 years (range, 2.7-20.9) and the mean follow-up duration after VNS implantation was 8.4 years (range, 1-15.5). At 0.5, 1, 3, and 5 years after implantation, 43.1, 50.0, 56.9, and 58.1 % of patients exhibited >= 50 % seizure frequency reduction disabling seizures. The patients with focal or multifocal epileptiform discharges were more likely to be responders than those with generalized epileptiform activities by video or conventional EEG at the time of VNS implantation (Pearson's and chi (2) test, p = 0.001). No other clinical variables were found to be associated with seizure outcomes. Wound infections caused VNS removal in two cases. All other adverse events, including cough and hoarseness, were tolerable. VNS is a well-tolerated and effective adjuvant therapy in pediatric patients with intractable epilepsy. Notably, patients with focal epileptiform discharges alone rather than those with generalized epileptiform discharges maybe better candidates for VNS.