Vagus nerve stimulation is a procedure that involves implantation of a device that stimulates the vagus nerve with electrical impulses.

There's one vagus nerve on each side of your body, running from your brainstem through your neck to your chest and abdomen.

Vagus nerve stimulation is most often used to treat epilepsy when other treatments haven't worked. Vagus nerve stimulation is also a treatment for hard-to-treat depression that hasn't responded to typical therapies.

Researchers are currently studying vagus nerve stimulation as a potential treatment for a variety of conditions, including multiple sclerosis, headache, pain and Alzheimer's disease.

In conventional vagus nerve stimulation, a device is surgically implanted under the skin on your chest, and a wire is threaded under your skin connecting the device to the left vagus nerve. The right vagus nerve is not used because it carries fibers that supply nerves to the heart.

When activated, the device sends electrical signals along the vagus nerve to your brainstem, which then sends signals to certain areas in your brain.

New, noninvasive vagus nerve stimulation devices, which do not require surgical implantation, have been approved for use in Europe to treat epilepsy, depression and pain but have not yet been approved for use in the U.S.

An implantable device that stimulates the right vagus nerve is also under study for the treatment of heart failure.