The Vagus Nerve and the Gut-Brain Axis

Published on Tuesday, March 22, 2022 by Ashlie Morrissey

A Closer Look At Your Vagus Nerve.

The Vagus Nerve is the key component of the gut-brain axis- meaning that information from the stomach and intestines (or gut) is transported to the brain and back to the gut from the brain along the Vagus Nerve.

This is the reason that a malfunctioning Vagus Nerve can profoundly affect gastrointestinal functioning, from the back of the throat to the bottom of the intestines, as well as mental health, in so many ways.

For a more science-heavy explanation this article from Bonaz et al. goes into further detail.

How Can You Assess Vagus Nerve Function?

The simplest way is to look at your uvula. If you look in your throat it’s the dangling piece in the center (make a loud clear “ahhhh” sound while looking in the mirror). Or, if possible, have a friend look in your throat with a light while doing this.

Sometimes the Vagus Nerve is assessed by checking your gag reflex by touching the back of your oral cavity with something soft to attempt to make you gag. These tests may appear normal or indicate the need for further testing. At this point there are a variety of tests that can be performed by medical providers, but unfortunately insurance may not cover these.

How Can Medical Providers Assess Vagus Nerve Function?

Some medical providers who specialize in assessing and treating Vagus Nerve, or Autonomic Nervous System issues, will perform Vagus Nerve Testing. This can involve testing the balance of the Autonomic Nervous System; as discussed in my last article this includes the sympathetic and parasympathetic systems.

This is done by measuring multiple signs at rest including: heart rate and variability, temperature, breathing rate, surface electromyography (muscle function testing), and sweat response.

Then the provider will monitor these signs while performing testing called “strenuous” or “dynamic” testing which may include: changing the head and neck position, exercises (e.g. squats), holding your breath, modified Valsalva maneuver (inhaling and exhaling against resistance), breathing rate, exposure to noise or music, performing analytical computations like math, and exposure to emotional stimulation.

Vagus Nerve Measurements may be performed using a special high-resolution ultrasound to evaluate if the diameter of the bilateral Vagus nerves is decreasing which indicates the nerve cells are dying. Also, Vagus Nerve blood flow can be evaluated by obtaining a carotid and subclavian artery ultrasound.

Further, and more invasive testing, can be performed and may include an echocardiogram to assess heart function, or a gastric emptying study to see how long it takes food to move through the stomach and into the intestines (this can also be accomplished by swallowing a “smart pill” that provides measurements but it depends on your provider and insurance what test is used), or an upper endoscopy which allows the medical provider to examine the upper digestive system.

To Find More Information or Medical Providers

To find a medical provider who performs this type of testing search for keywords: “vagopathy” which is the medical term for poor Vagus Nerve functioning, or: “dysautonomia” which is the much broader term for dysfunction of any of the nerves that regulate involuntary body functions. These keywords can lead you to professionals in your area.

There are also numerous organizations that offer support and information:

The Dysautonomia Project has both education and a “Find a Physician” area: https://thedysautonomiaproject.org/

Dysautonomia International has numerous areas of the website with links to support groups, information about research, and information about workplace accommodations. It does primarily mention one aspect of dysautonomia: Postural Orthostatic Tachycardia Syndrome (POTS), however the information is applicable for all dysautonomias. http://www.dysautonomiainternational.org/

The American Autonomic Society is the professional society for medical professionals and researchers who specialize in dysautonomias. If you want to deep dive into the cutting edge articles, this is the place for you. https://americanautonomicsociety.org/