Mechanisms and state of the art of vagus nerve stimulation

Vagus nerve stimulation (VNS) is an established treatment of medically refractory partial-onset seizures. Recent data from an open-label multicenter pilot study also suggest a potential clinical usefulness in the acute and maintenance treatment of drug-resistant depressive disorder. Despite the fact that surgery is needed to implant the stimulating device, the option of long-term use largely devoid of severe side effects would give this treatment modality a privileged place in the management of drugresistant depression. However, definite therapeutic effects of clinical significance remain to be confirmed in large, placebocontrolled trials. Besides the potential clinical usefulness, VNS can be used as a research tool in epilepsy patients implanted for clinical reasons, allowing neurophysiologic investigations of the parasympathetic system and its interactions with other parts of the central nervous system.