Many of the symptoms such as dizziness and difficulty in swallowing connected to post-Covid syndrome (PCC, also known as long Covid19) could be linked to the effect of the virus on the vagus nerve – one of the most important multi-functional nerves in the body, according to a study led by researchers from Spain.

The study is to be presented at European Congress of Clinical Microbiology and Infectious Diseases to be held in April this year. The study is by Dr Gemma Lladós and Dr Lourdes Mateu, University Hospital Germans Trias i Pujol, Badalona, Spain, and colleagues.

The vagus nerve extends from the brain down into the torso and into the heart, lungs and intestines, as well as several muscles including those involved in swallowing.  As such, this nerve is responsible for a wide variety of bodily functions including controlling heart rate, speech, the gag reflex, transferring food from the mouth to the stomach, moving food through the intestines, sweating, and many others.

The researchers noted that the long Covid is a potentially disabling syndrome affecting an estimated 10-15% of subjects who survive the infection. The authors proposed that SARS-CoV-2-mediated vagus nerve dysfunction (VND) could explain some long Covid symptoms, including dysphonia (persistent voice problems), dysphagia (difficulty in swallowing), dizziness, tachycardia (abnormally high heart rate), orthostatic hypotension (low blood pressure) and diarrhoea.

The authors performed a pilot study on 348 patients, extensive morphological and functional evaluation of the vagus nerve, using imaging and functional tests in a prospective observational cohort of long Covid subjects with symptoms suggestive of VND between March and June 2021. The study is ongoing, and continues to recruit patients.

Eating and digestive function was also affected in some patients, said the researchers.

 “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,” said the authors.