Transcutaneous vagus nerve stimulation (tVNS) protocol for the treatment of major depressive disorder: A case study assessing the auricular branch of the vagus nerve.

Abstract

In current psychiatric research, cutting-edge noninvasive neuromodulation interventions such as trigeminal and transcutaneous vagus nerve stimulation (TNS and tVNS, respectively) are driven by data from both functional neuroimaging studies and experimental research that help targeting specific brain areas related to psychiatric disorders. The rationale for using trigeminal or vagus nerves for delivering electric current toward specific brain areas is the anatomical correlation these nerves maintain with sites related to psychiatric symptoms such as the amygdala, insula, precentral gyrus, hippocampus, thalamus, and prefrontal cortex (structures widely related to cognitive functioning and mood regulation). Therefore, both TNS and tVNS modulate brain structures according to the “bottom-up” hypothesis, in which stimulation of these nerves would propagate via their cortical and subcortical projections [ 1 Wagner S. Doering B. Helmreich I. Lieb K. Tadic A. A meta-analysis of executive dysfunctions in unipolar major depressive disorder without psychotic symptoms and their changes during antidepressant treatment. Acta Psychiatr Scand. 2012; 125: 281-292 Crossref PubMed Scopus (124) Google Scholar , 2 Shiozawa P. Silva M.E. Carvalho T.C. Cordeiro Q. Brunoni A.R. Fregni F. Transcutaneous vagus and trigeminal nerve stimulation for neuropsychiatric disorders: a systematic review. Arq Neuropsiquiatr. 2014; 72: 542-547 Crossref PubMed Scopus (71) Google Scholar , 3 Schrader L.M. Cook I.A. Miller P.R. Maremont E.R. DeGiorgio C.M. Trigeminal nerve stimulation in major depressive disorder: first proof of concept in an open pilot trial. Epilepsy Behav. 2011; 22: 475-478 Abstract Full Text Full Text PDF PubMed Scopus (48) Google Scholar ].