Therapeutic effects of vagus nerve stimulation in epilepsy and implications for sudden unexpected death in epilepsy.

Vagus nerve stimulation (VNS) is a non-pharmacological therapy approved by the FDA for treatment of patients with partial-onset epilepsy. The most frequently encountered adverse effects typically occur during stimulation, are usually mild to moderate in severity, and resolve with reduction in current intensity or spontaneously over time. There are no apparent effects of VNS on vagally mediated visceral function. Though the precise mechanism of action of VNS remains unknown, available evidence suggests that central autonomic nervous system pathways are involved, which have also been implicated in sudden unexpected death in epilepsy (SUDEP). Studies to date of VNS and SUDEP are limited and do not conclusively show an association between VNS and SUDEP rates independent of other epilepsy-specific variables.