Questions & Answers: What is vagus nerve stimulation?
Q. What is vagus nerve stimulation?
A. The word "vagus" means "wandering," which is what the long vagus nerve does. It runs from the base of the brain through the neck and chest to the stomach, conveying visceral and taste sensations to the brain and regulating the muscles that control breathing, digestion, the vocal cords, and the circulation of the blood.
In the early 1990s, physicians began to notice that electrical stimulation of the vagus nerve could reduce the rate of epileptic seizures. The treatment, known as vagus nerve stimulation (VNS), was approved by the FDA to treat seizures that do not respond to medications. Since 1997, tens of thousands of patients have had the VNS device installed for that purpose. An electric pulse generator is implanted in the chest and attached to a tube containing electrodes, which is wrapped around the vagus nerve where it passes through the neck. The generator, programmed by passing a wand over the chest, applies a stimulus for 30 seconds every five minutes, 24 hours a day. The battery that drives the generator lasts 5–10 years.
What's useful for epilepsy — anticonvulsant drugs, for example — may also be useful for depression. And physicians soon noticed that depressive symptoms improved in some of their epileptic patients no matter how well the treatment worked for seizures. After further investigation, VNS received FDA approval in 2004 for the treatment of depression that does not respond to at least four antidepressant trials.