Vagal Nerve Stimulation – from Chaos to Order
Vagal Nerve Stimulation – from Chaos to Order
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Vagal Nerve Stimulation – from Chaos to Order 〰️
The array of end organ innervations of the vagus nerve, coupled with increased basic science evidence, has led to vagus nerve stimulation (VNS) being explored as a management option in several clinical disorders, such as heart failure, migraine, and inflammatory bowel disease. Invasive (surgically implanted) and non-invasive (transcutaneous) techniques of VNS exist. Transcutaneous VNS (tVNS) delivery systems rely on the cutaneous distribution of vagal afferents, either at the external ear (auricular branch of the vagus nerve - ABVN) or at the neck (cervical branch of the vagus nerve), thus bypassing the need for surgical implantation of a VNS device and encouraging further investigations across a wide range of uses due to its greater facility. The ABVN is the only peripheral branch of the vagus nerve distributed on the ear’s surface, so it should be possible to achieve efficacy like that of implanted VNS by activating the central vagal pathways. It is reasonable to assume that the concha and inner tragus are suitable locations for vagal modulation. Both research and clinical practice demonstrate that tVNS elicits hypo and hyperactivation in various regions of the brain associated with anxiety and mood regulation, the mechanism of action and influence of stimulation parameters on clinical outcomes remains predominantly hypothetical. Beyond anxiety and mood regulation, tVNS has also been investigated for several other disorders, including autism spectrum disorder, tinnitus, migraine, and pain, by targeting the vagus nerve at sites in both the ear and the neck. As most of the described methods differ in the parameters and protocols applied, there is currently no firm evidence on the optimal location for tVNS or the stimulation parameters that provide the greatest therapeutic effects for a specific condition. The presenter will provide an overview of tVNS theory and tVNS stimulation using a variety of extant technologies for symptom relief and improvement of vagal tone.