According to Cyberonics, VNS Therapy “uses a surgically implanted medical device that delivers pulsed electrical signals to the vagus nerve.” The therapy is marketed to approximately 60 countries worldwide, and over 55,000 patients have been implanted with the device as of May 2010.
The therapy treated patients with chronic treatment-resistant depression in July 2005. The results showed a significant decrease in depression symptoms in all patient groups, measures by proved depression assessment scales. Over the 50 week treatment, overall depression symptom improvements ranged from 32.4% to 42%, while response rates ranged from 26.7% to 53.3% and remission rates ranged from 14.6% to 22.5%.
More information on the results of this study can be found here: “Cyberonics Announces Data from Depression Dosing Study: VNS Therapy(R) Effective at Reducing Depressive Symptoms in Patient Population Experiencing Chronic and Recurrent Treatment-Resistant Depression“