Long COVID may be caused by SARS-CoV-2-mediated vagus nerve dysfunction (VND), according to a Spanish study.

According to new research, many symptoms of post-COVID syndrome may be caused by long-term damage to one of the human body’s most critical nerves following the initial infection with coronavirus.

What is the function of the vagus nerve?

The vagus nerve is the longest and most complicated of all of the cranial nerves. It goes from the brain to the abdomen, passing through the entire face and chest. The vagus nerve connects the brain to the gastrointestinal tract, conveying information about the state of the internal organs back to the brain.

The vagus nerve not only controls the passage of food from the mouth to the stomach and moves food through the intestines, but it also controls the heart rate, perspiration production, and the gag response, as well as specific muscle movements in the mouth, including those required for speech.

A new study will be presented at this year’s European Congress of Clinical Microbiology and Infectious Diseases (ECCMID) examines the relationship between post-COVID syndrome, also known as long COVID, and the vagus nerve.

Dr. Gemma Lladós and Dr. Lourdes Mateu of the Germans Trias I Pujol University Hospital in Badalona, Spain, co-authored the pilot study. The findings will be presented at the meeting, which will take place in Lisbon from April 23 to April 26.

Symptoms of long-term COVID:

Many of the symptoms of chronic COVID, including chronic voice problems, trouble swallowing, dizziness, abnormally high heart rate (tachycardia), low blood pressure, and digestive issues, may be caused by SARS-CoV-2-mediated vagus nerve dysfunction (VND), according to the study.

Long COVID is a condition marked by the persistence of COVID-19-related health problems after the patient has recovered from the original infections. It has the potential to damage practically every organ in the body, as well as cause a variety of mental-health and nervous-system issues. Fatigue, headaches, shortness of breath, loss of smell and taste, and muscle weakness are some of the most prevalent symptoms of extended COVID.

In an assessment of individuals with prolonged COVID who exhibited one or more indicators of VND, the researchers performed imaging and functional tests, as well as a morphological and functional evaluation of the vagus nerve, to better explain the phenomena.

Two-thirds (228) of the 348 participants in the research showed at least one symptom of VND among their long COVID symptoms. Following the completion of the initial examinations, a test group of 22 patients with VND symptoms was evaluated further.

Twenty of the 22 people studied were women, with a median age of 44. The symptoms had been present for an average of 14 months in the subjects.

Diarrhea (73 percent of respondents), tachycardia (59 percent), dizziness, trouble swallowing, and vocal issues were the most common VND symptoms (45 percent each). Low blood pressure was also a problem for 14 percent of the individuals.

At least three separate VND-related symptoms were reported by 86 percent of the patients surveyed.

There were also changes that could be seen in ultrasounds in six out of the 22 patients. In these patients, the vagus nerve was thicker and showed signs of mild inflammation.

The study’s ten patients had aberrant breathing patterns and lower maximal inspiration pressures, indicating weakening in the breathing muscles, which are also associated to the vagus nerve.

A positive test for oropharyngeal dysphagia, or problem swallowing, which can disrupt the digestive process, was seen in 13 of 18 patients (72 percent). Eight of the patients had limited or impaired ability to carry food to the stomach via the esophagus, while others had acid reflux.

Closer to treatment
Since the specific origin of extended COVID is unknown, as is the reason why symptoms vary so much from patient to patient, the study’s findings could have a substantial impact on future research and treatment of the disorder.

“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,” the study’s authors said. “Our findings so far thus point at vagus nerve dysfunction as a central pathophysiological feature of long COVID.”

Image Credit: Getty

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