Vagus nerve stimulation in children with drug-resistant epilepsy: Age at implantation and shorter duration of epilepsy as predictors of better efficacy?

Abstract

Aim. To study the efficacy of vagus nerve stimulation (VNS) therapy in a highly drug-resistant childhood epilepsy patient group and to investigate the effect of age at implantation on efficacy. Methods. The efficacy of VNS treatment was analysed in a cohort of 70 patients with drug-resistant epilepsy. Both children with focal (n=16) and generalized epilepsies (n=54) were included. Age at implantation varied between 19 months and 25 years. Results. Overall, responder rate was 54% with 5.7% children becoming seizure-free. The only factor in our analysis that could predict good outcome was age at implantation. In the youngest group (<5 years), the responder rate was 77% and this group also included three of the four seizure-free children. These three seizure-free children were known to have tuberous sclerosis. There were no outcome differences between generalized and focal epilepsies. Conclusions. Our single centre study confirms previous studies on the efficacy of VNS in children. A larger study using multivariate analysis to disentangle the contribution of different factors (such as age at implantation, aetiology, and epilepsy duration) is necessary to confirm our preliminary finding that younger age at VNS implantation might result in a better outcome.