Context: Treatment Resistant Depression (TRD) is relatively common in clinical practice and is associated with high levels of disability. Advances in the understanding of the biological basis of depression has led to efforts to find effective treatments for this patient population.
Objectives: To provide a literature update relating to the effectiveness and mechanisms of action of Vagus Nerve Stimulation (VNS).
Key messages: Early clinical observations and subsequent prospective studies indicated that VNS had the potential to improve mood in patients with epilepsy. Subsequent studies have evaluated the effect of VNS in treatment resistant major depression. These initial studies indicate a significant short and long-term benefit of VNS on mood. Although the precise mechanisms underlying the antidepressant effect of VNS remain obscure, there is emerging evidence that VNS is associated with alteration of CSF concentrations of various neurotransmitters. Furthermore, VNS impacts on functional activity of brain areas within the limbic system.
Conclusion: VNS is an emerging as a potentially valuable treatment for some individuals with TRD. The precise mode of action of its antidepressant effect remains obscure, but there is mounting evidence of modulation of neurotransmission and functional activity in brain regions implicated in affective regulation.
