One of the human body’s most important nerves is the vagus nerve, the longest and most complex of the 12 cranial nerves. Extending through the face, chest, and into the abdomen, the vagus nerve serves as the primary messaging link between the brain and gastrointestinal (GI) tract, allowing the brain to monitor the inner organs. It controls the movement of food through the GI tract, and serves other vital functions such as the regulation of heart rate and sweat production.

New research shows a link between vagus nerve damage from initial coronavirus infection and mysterious post-COVID syndrome, or long COVID, which can affect virtually all organ systems.

What The Researchers Did

The findings come from a small, initial study by Drs. Gemma Lladós and Lourdes Mateu of the Germans Trias i Pujol University of Badalona, Spain. 

The researchers propose that some of the symptoms of long COVID are suggestive of vagus nerve dysfunction (VND): persistent voice issues, difficulty swallowing, dizziness, rapid heartbeat (tachycardia), low blood pressure (orthostatic hypotension), and diarrhea.

• Using imaging and functional tests, the researchers evaluated the vagus nerve in a group of long-COVID patients showing one or more symptoms indicative of VND.
• The first 22 of 228 patients from the Germans Trias i Pujol University Hospital Long COVID Clinic having at least one VND symptom were selected for the pilot study.
• The participants were evaluated between March and June 2021, with research ongoing.
• Twenty of the 22 patients were women, median age 44, who had symptoms for an average of 14 months.

What They Found

The findings support the authors’ theory that many long-COVID symptoms could be attributed to VND, with a high percentage of the 22 patients presenting with:

• Diarrhea (73%)
• Tachycardia (59%)
• Dizziness, difficulty swallowing, voice issues (45% each)
• Low blood pressure (14%) 

Nearly all long-COVID patients (19 or 86%) had a minimum of three VND symptoms. 

Furthermore:

• Six (27%) of the patients showed visible changes to the vagus nerve in the neck via ultrasound, including thickening and mild reactive inflammatory changes.
• Ten (46%) of the patients showed abnormal breathing, and 10 of 16 assessed patients (63%) showed reduced maximum inspiratory pressure, both of which indicate weak breathing muscles (also controlled by the vagus nerve).
• Thirteen of 18 assessed patients (72%) reported trouble swallowing (dysphagia), while eight of 19 patients (42%) showed difficulty transferring food to the stomach via the esophagus, and nine of 19 patients (47%) experienced acid reflux.

What It Means

Since the exact cause of long COVID and why symptoms vary among patients aren’t yet known, the discovery could have a significant impact on our understanding and treatment of the disease.

Concluded the authors in a news release by the European Society of Clinical Microbiology and Infectious Diseases:

“In this pilot evaluation, most long-COVID subjects with vagus nerve dysfunction symptoms had a range of significant, clinically relevant, structural and/or functional alterations in their vagus nerve, including nerve thickening, trouble swallowing, and symptoms of impaired breathing. Our findings so far thus point at vagus nerve dysfunction as a central pathophysiological feature of long COVID.”

The authors will present their findings at the 2022 European Congress of Clinical Microbiology and Infectious Diseases (ECCMID) in Lisbon April 23-26.

*Silkoff, S. (2022, February 14). New research points to possible reason for long COVID. The Jerusalem Post. https://www.jpost.com/health-and-wellness/article-696452