[Vagus Nerve Stimulation (VNS) in Depression]

Major depressive disorder is a common mental health disease with a chronic and treatment-resistant course in about one-third of patients. Invasive vagus nerve stimulation (VNS) as a long-term adjunctive treatment option has increasingly been used in the last years. VNS was CE-certified in the European Union for use in chronic and treatment-resistant depression in 2001. Method In this narrative literature review we provide an overview on VNS as a treatment option in patients with depression. We particularly focus on aspects with high clinical relevance. Results Indication to conduct VNS is determined after comprehensive evaluation of the patients' symptoms and psychiatric history. After education of patients and caregivers and obtaining informed consent, a pacemaker-like pulse generator is implanted in the left chest in a short surgical procedure. In the first weeks after implantation, the stimulation is turned on stepwise in an outpatient setting. The left vagal nerve is stimulated for 30 sec. every 5 minutes. Hoarseness during stimulation is the most frequent side-effect. There is a delay in the onset of antidepressant action of about 6-12 months. In a large registry, the cumulative response rate after 5 years was significantly higher (67.6%) in patients treated with VNS plus treatment-as-usual (TAU) than TAU alone (40.9%). Long-term benefits of VNS on quality of life, cognition, morbidity and mortality have been described previously. Conclusion VNS is a long-term safe treatment option in severely affected patients with depression with positive impact on depression severity, quality of life and cognitive function. Increase of monoaminergic transmission and anti-inflammatory effects of VNS are possible mechanisms of action.