Vagus nerve stimulation (VNS) is a treatment method that involves placing a small electrical device (similar to a pacemaker) in the body to stimulate the vagus nerve. The vagus nerve runs from the brain to the abdomen, passing through numerous organs. It is one of the most important nerves in the body. It is thought that stimulating the vagus nerve may help to treat disorders of the brain and nervous system. Currently, VNS is approved by the Food and Drug Administration (FDA) to treat epilepsy and some forms of chronic depression. Its effectiveness is still being evaluated, particularly with respect to depression.

The stimulator is inserted into the chest and its electrodes are placed around the vagus nerve in the neck. This surgical procedure is usually performed under general anesthesia, although sometimes it is done under local anesthesia. The device is programmed to stimulate the nerve at regular intervals. Patients are supplied with a magnet, which they can use to deliver extra stimulation when needed (if, for example, they feel a seizure coming on). The magnet can be used to turn the device off.

The most common side effects from VNS include:

• Hoarseness
• Sore throat
• Change in voice tone during stimulation
• Tickling in the throat

These side effects are usually mild and generally subside over time.

VNS can be used to help control seizures that have not responded to seizure medication or conventional brain surgery. It can also be used to treat severe medication-resistant depression. In both cases, medication is still required to control symptoms. Studies are currently under way to test the effectiveness of vagus nerve stimulation for the treatment of migraines, chronic pain and Alzheimer's disease.