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Medical Devices

VNS Therapy System - P970003s050

Diagram of VNS Therapy System - P970003s050This is a brief overview of information related to FDA's approval to market this product. See the links below to the Summary of Safety and Effectiveness and product labeling for more complete information on this product, its indications for use, and the basis for FDA's approval.

Product Name: VNS Therapy System
Manufacturer: Cyberonics, Inc.
Address: 100 Cyberonics Blvd., Houston, TX 77058
Approval Date: July 15, 2005
Approval Letter:

What is it? The device is a totally implanted vagus nerve stimulator (VNS) for the long-term treatment of chronic or recurrent depression which has not responded to usual treatments. The device was initially approved in 1997 for epilepsy.

How does it work? A pulse generator, similar to a pacemaker, is surgically implanted under the skin of the left chest and an electrical lead (wire) is connected from the generator to the left vagus nerve. Electrical signals are sent from the battery-powered generator to the vagus nerve via the lead. These signals are in turn sent to the brain. To turn the stimulator off, the patient holds a magnet over the pulse generator.

When is it used? The device is to be used only in patients 18 years of age or over with treatment-resistant depression (TRD). These are patients who have been treated with, but failed to respond to, at least 4 adequate medication and/or ECT treatment regimens prescribed by their physician. It is not intended to be used as a first-line treatment, even for patients with severe depression. It should be prescribed and monitored only by physicians who have specific training and expertise in the management of treatment-resistant depression and the use of this device. It should be implanted only by physicians who are trained in surgery of the carotid sheath and have received specific training in the implantation of this device.

What will it accomplish? The VNS Therapy System is intended to reduce symptoms of depression. However, this therapy may be required for several months before any benefit is noticed by the patient. Not all patients receiving this therapy will respond to the same degree, if at all. Based on the results of a clinical study of over 200 patients conducted in the United States, during the first 3 months of therapy, patients who had the device implanted and turned on did not show any significant advantage in response compared to patients in whom the device was implanted but not turned on. At 1 year, approximately 2 or 3 out of every 10 subjects had a clinically significant improvement in symptoms of depression with about half that number having almost no remaining depressive symptoms. Many of the patients who had a significant response within the first year of treatment continued to have a similar degree of response through 2 years.

Some patients, however, had no improvement in symptoms and some actually got worse. This therapy is intended to be given along with other traditional therapies, such as medications and ECT, and patients should not expect to discontinue these other treatments, even with the device in place. Patients will require regular visits to their physicians for adjustments to their device and other treatments. Patients receiving VNS therapy may experience various side effects from the stimulation including hoarse voice, cough, shortness or breath, difficulty swallowing, and neck pain, some of which may persist as long as the device is active.

When should it not be used? It cannot be used in patients who have had their vagus nerve cut or who will be exposed to diathermy which is a form of ultrasound.

Additional information: Summary of Safety and Effectiveness and labeling are available at:

Page Last Updated: 09/04/2013
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