What is vagus nerve stimulation?

Vagus nerve stimulation (VNS) is a type of neuromodulation in which a surgically implanted device delivers electrical pulses to a nerve in the neck called the vagus nerve. VNS is used most commonly for epilepsy, but it has also shown promise for treating severe depression.

A VNS system consists of two components. A thin wire is inserted into the left side of the neck and wrapped around the vagus nerve. The wire is passed under the skin to a small battery that is implanted under the collarbone, similar to a heart pacemaker. Below is an image of a sample battery with a quarter for scale.

What are the surgery and recovery like?

VNS is implanted by a neurosurgeon under general anesthesia as an outpatient surgery. This means there is no need for an overnight hospital stay. There are two short incisions, one over the front of the neck that I hide within one of the natural skin folds, and another just beneath the collarbone.

You can resume your regular activities almost right away. Some tenderness of the areas around the incision is normal in the beginning. The device is turned on in your neurologist's office a few weeks after surgery. Usually the device is started at a low setting and then ramped up slowly over several office visits.

How does the device work?

For reasons we don't entirely understand, pulses of electricity applied to the vagus nerve result in a reduction in seizures. Modern VNS devices have three therapy modes. The first is a dose of stimulation that is delivered on schedule every five or six minutes. The second is an on-demand mode in which you can activate the stimulator with a wristband if you feel a seizure coming on. Finally, there is a heart rate detection mode that constantly monitors your heartbeat for signs of an impending seizure and then delivers therapy when one appears to be starting. Clinical studies suggests that each of these modes contributes to seizure control in epilepsy patients.

What are benefits and risks?

In the case of epilepsy, VNS is the only surgical treatment that does not involve a procedure on the brain, which makes it comparatively safe. Benefits of VNS observed in clinical trials include improved seizure control and quality of life as well as a reduced risk of sudden death from epilepsy (SUDEP). If you are an epilepsy patient with depression, you might also see an improvement in your mood. But VNS is not a cure for epilepsy, so even though patients experience fewer and less severe seizures, it is rare for seizures to disappear entirely.

The main risk of VNS therapy is infection of the device. VNS can also cause side effects related to your throat and voice; many patients notice a tickling or hoarseness in the throat when the device is giving a dose of stimulation; this often gets better over time.