What is Vagus Nerve Stimulation (VNS)?Vagus Nerve Stimulation, or VNS, involves the use of an implanted device to provide periodic stimulation to the vagus nerve. The device was originally developed as a treatment for epilepsy. It has since been approved in the U.S., Canada and the European Union for treatment-resistant depression in both unipolar depression and bipolar disorder.
How Does It Work?
A pulse generator, which is a device similar to a pacemaker, is surgically implanted under the skin of the left chest. An electrical lead (wire) connects the device to the left vagus nerve. The device generates a periodic electrical impulse (30 seconds on, five minutes off) which is sent through the electrical lead to the vagus nerve. Although scientists do not know exactly how vagus nerve stimulation helps depression, it is believed that the vagus nerve conducts the signal from the device to areas in the brain that affect mood.
Who Is a Candidate for VNS?The device is intended to be used for patients 18 year of age or older with treatment-resistant depression (TRD). TRD is defined as having failed to respond to either four adequate medication trials or treatment with electroconvulsive therapy (ECT).
It cannot be used in patients who have had their vagus nerve cut or who will be exposed to a form of ultrasound called diathermy.
The Implant Procedure
The pulse generator is implanted under the skin of the left chest using a small incision. The pulse generator is placed inside a pocket under the skin that the surgeon creates for it. Another incision is made in the lowest part of the neck on the left side. The leads are attached to the pulse generator and then a tool is used to tunnel the leads under the skin up to the vagus nerve in the neck, where they are attached to the nerve. Surgery takes anywhere from 45 minutes to two hours to perform and is done under either local, regional or general anesthesia, depending what your surgeon feels is appropriate for you. Generally it is done as an outpatient procedure, although some patients may need to stay overnight.
What Happens After the Procedure?
Patients can generally go home the same or the following day. You may feel some stiffness or soreness around the area of the implant for a few days. Your doctor will give you medication for the pain. You will need to return for a checkup the following week so that the incision sites can be checked and the pulse generator can be programmed or adjusted.
Maintenance of the Device
The device comes with a programming wand and software, which are used to program the device or turn it off if necessary. You will eventually need surgery to replace the generator when the battery wears out. How quickly the battery wears out depends upon its settings, but on the average it lasts about six years. Replacement of the generator is generally an outpatient procedure under local anesthetic that takes about one hour to complete.
What Are the Risks?
- As with any procedure where you are put under anesthesia, there is a small possibility of death.
- Over half of patients will experience hoarseness, which lessens over time.
- Other less common side effects are increased cough, shortness of breath, neck pain, sore throat, tingling, nausea and pain at the site of the incision.
What Are the Benefits?
- Because the device is implanted in the body and works automatically, compliance with the treatment regimen is assured.
- The implantation procedure is safe.
- The use of the device itself is safe.
- There are no drug interactions to worry about.
- There is no memory loss like what occurs with ECT.
- The therapy can be effective in alleviating depression when all other treatments have failed.
Donovan, Charles E. Out of the Black Hole: The Patient's Guide to Vagus Nerve Stimulation and Depression St. Louis MO : Wellness Publishers, 2005.