This is a postmarket medical device study. This study will examine treatment outcomes for patients with TRD who are randomized to VNS Therapy administered at different amounts of electrical charge. The Sponsor, Cyberonics, provides funding for this study. Patients are followed for 54 weeks, 50 of those weeks are following implantation of the VNS Therapy system. No study sites will be permitted to enroll study subjects until Institutional Review Board (IRB) approval has been received. Sites are permitted to be approved by a local or a central IRB.
This is a postmarket medical device study. The objective of this study is to compare the safety and effectiveness of Vagus Nerve Stimulation (VNS) Therapy administered at different amounts of electrical charge for the treatment of patients with treatment-resistant depression (TRD).