Vagus nerve stimulation (VNS) for treatment-resistant depressions: A multicenter study

Background: Vagus nerve simulation (VNS) delivered by the Neurocybernetic P rosthesis (NCP) System was examined for its potential antidepressant effect s. Methods: Adult outpatients (n = 30) with nonpsychotic, treatment-resistant major depressive (n = 21) or bipolar I (n = 4) or II (n = 5; depressed phas e) disorders who had failed at least two robust medication trials in the cu rrent major depressive episode (MDE) while on stable medication regimens co mpleted a baseline period followed by NCP System implantation. A 2-week, si ngle-blind recovery period (no stimulation) was followed by 10 weeks of VNS . Results: In the current MDE (median length = 4.7 years), patients had not a dequately responded to two (n = 9), three (n = 2), four (n = 6), or five or more (n = 13) robust antidepressant medication trials or electroconvulsive therapy (n = 17). Baseline 28-item Hamilton Depression Rating Scale (HDRS2 8) scores averaged 38.0. Response rates (greater than or equal to 50% reduc tion in baseline scores) were 40% for both the HDRS28 and the Clinical Glob al Impressions- Improvement index (score of 1 or 2) and 50% for the Montgom ery-Asberg Depression Rating Scale. Symptomatic responses (accompanied by s ubstantial functional improvement) have been largely sustained during long- term follow-up to date. Conclusions: These open trial results suggest that VNS has antidepressant e ffects in treatment-resistant depressions. Biol Psychiatry 2000;47:276-286 (C) 2000 Society of Biological Psychiatry.