Transcutaneous auricular vagal nerve stimulation (taVNS) might be a mechanism behind the analgesic effects of auricular acupuncture

BACKGROUND: Randomized clinical trials (RCT) demonstrated that auricular acupuncture (AA) is effective in treatment of acute and chronic pain, although the mechanisms behind AA are not elucidated. METHODS: The data concerning the localization of AA points, which are commonly used to treat pain, were extracted from the meta-analysis of 17 RCTs and evaluated using the anatomical map of auricular afferent nerve supply. RESULTS: Fifteen out of 20 specific AA points, used in the treatment of pain, are situated in areas innervated mostly by the auricular branch of the vagal nerve (ABVN), whereas sham stimulation was applied at the helix of the auricle, innervated by cervical nerves. CONCLUSION: Considering the clinical data relating to the anatomy of neural pathways and experimental findings of the mechanisms of transcutaneous auricular vagal nerve stimulation, the analgesic effects of AA may be explained by stimulation of ABVN.