Vagus nerve stimulation

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Depression is usually a very treatable condition. Often, standard treatment with antidepressant medications, psychotherapy or electroconvulsive therapy can help improve even severe cases of depression.

But if standard depression treatment doesn't work, a relatively new type of treatment involving brain stimulation may be an option. In mid-2005, the Food and Drug Administration (FDA) approved a type of brain stimulation called vagus nerve stimulation for certain types of depression.
How vagus nerve stimulation works

The vagus nerve serves as a primary communication pathway between your brain and such major organs as your heart, lungs and intestines. There's one vagus nerve on each side of your body. The nerve runs from your brainstem through your neck and down to your chest and abdomen. Information travels through this nerve to and from your central nervous system.

Vagus nerve stimulation uses electrical impulses to affect mood centers in the brain by stimulating the vagus nerve. The treatment is sometimes called vagal nerve stimulation.

With vagus nerve stimulation, a device called a pulse generator is surgically implanted in the upper left side of your chest. The device is about the size of a stopwatch. A lead wire is connected to the pulse generator. The lead wire is guided under your skin from your chest up to your neck, where it's attached to the left vagus nerve.

Electrical signals travel from the pulse generator, through the lead wire and to the vagus nerve. The vagus nerve delivers those signals to the brain. But precisely how stimulation of the vagus nerve may improve depression remains unknown. Research indicates that vagus nerve stimulation alters the functioning of brain areas involved in mood regulation and depression.

The pulse generator can be programmed to deliver electrical impulses to the nerve at various durations, frequencies and currents. Stimulation typically lasts for 30 seconds and occurs every five minutes. The device is meant to be a permanent implant. It runs on battery power. The stimulation doesn't typically cause any sensations in your body.

In vagus nerve stimulation, an implanted pulse generator and lead wire stimulate parts of your brain that affect mood.
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Who may benefit from vagus nerve stimulation

Vagus nerve stimulation may not be appropriate for all cases of depression. In fact, the FDA approved use of vagus nerve stimulation in depression only for these specific situations:

* For treatment of long-term, chronic depression that lasts two or more years, in conjunction with standard treatments
* Recurrent or severe depression
* Depression that hasn't improved after the use of at least four other treatments, such as four different antidepressants

The approval of vagus nerve stimulation for depression didn't come without controversy, though. In fact, some FDA scientists repeatedly recommended against its approval. Not all scientific studies have shown that vagus nerve stimulation is an effective treatment for depression. In fact, some studies have suggested it's no more effective than a placebo. Additional research will help determine its long-term effectiveness and safety.
Side effects of vagus nerve stimulation

Vagus nerve stimulation may cause harmful side effects. For one thing, you may have complications from the surgery to implant the device. In addition, the device and the stimulation may cause unwanted or harmful side effects. However, the frequencies and currents of the electrical impulses can be adjusted to help minimize these effects.

Common side effects and adverse health problems associated with vagus nerve stimulation include:

* Voice changes
* Hoarseness
* Cough
* Neck pain
* Breathing problems, especially during exercise
* Difficulty swallowing
* Tingling or prickling of the skin
* Sore throat

There's also a small risk that the pulse generator may malfunction or move about within your body. You may then require additional surgery to fix or remove the device.

If necessary, you can deactivate the pulse generator temporarily. You may want to do this if you have intolerable side effects or you want to engage in heavy exercise. To deactivate it, you hold a magnet over the area of your chest where it's implanted.

On the other hand, vagus nerve stimulation doesn't have the side effects that are typical of antidepressants. For instance, it's not associated with weight gain, sexual problems, memory problems, food or medication interactions, or sleep disturbances.
Balancing the pros and cons of vagus nerve stimulation

Interest in stimulating the brain to treat depression has grown in recent years. Researchers believe that changing the function of the brain in areas that control mood may help relieve symptoms of depression. Researchers hope to find a treatment that mimics the positive effects of electroconvulsive therapy (ECT) but that doesn't have the health risks and adverse side effects of ECT.

Because vagus nerve stimulation and certain other forms of brain stimulation are so new in depression treatment, you must carefully consider the pros and cons of these kinds of treatments. The long-term effects are still under study. However, if your depression is severe and long lasting, vagus nerve stimulation may be an option to discuss with your health care team.

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