Awakening the Vagus: Transcutaneous Auricular Vagus Nerve Stimulation—A Narrative Review

Abstract

Highlights What are the main findings? taVNS has a potential neuromodulatory effect that can influence cortical and EEG reactivity, particularly in patients in a minimally conscious state. What are the implications of the main findings? taVNS is a low-risk, easily implementable adjunct for a vulnerable population with few treatment options. Larger multicenter RCTs with standardized protocols are needed before considering routine clinical adoption of taVNS. Abstract Disorders of consciousness (DoC), including unresponsive wakefulness syndrome/vegetative state (UWS/VS) and minimally conscious state (MCS), remain a major challenge in clinical neurology. Therapeutic options are limited, and prognosis is often uncertain. Transcutaneous stimulation of the auricular branch of the vagus nerve (taVNS) is a non-invasive neuromodulation technique that has gained increasing interest as a potential strategy to promote recovery of consciousness. This narrative review summarizes the anatomical and functional rationale of taVNS, compares invasive and non-invasive vagus nerve stimulation techniques, reviews the biological mechanisms underlying its effects, discusses established clinical applications, technological innovations, and available clinical trial evidence. Current data suggest that taVNS is safe and well-tolerated, with preliminary evidence of applicability in DoC, particularly in patients with MCS. However, heterogeneity in stimulation protocols and the limited number of large-scale randomized controlled trials highlight the need for further standardized research.