Estimating Long-Term Vagus Nerve Stimulation Effectiveness: Accounting for Antiepileptic Drug Treatment Changes.

VNS is a well-tolerated palliative neuromodulatory treatment for drug resistant epilepsy with a 43.8% seizure reduction after five years. Our data supports the idea that VNS effectiveness increases with time. Therefore we suggest that VNS should be evaluated for at least two years after implantation. AED changes should try to be kept to a minimum during evaluation in order to determine the effectiveness of VNS.