Two studies to be presented at forthcoming meetings of the professional community suggest that some prolonged COVID-19 symptoms may be related to the effect of SARS-CoV-2 on the vagus nerve and that the use of enhanced external counter-pulsation (EECP) – which increases blood flow – can improve some of these symptoms, respectively.
Long COVID can affect up to 15% of those who survive their infections, causing symptoms such as fatigue, muscle aches and cognitive problems that linger for several months. None of the surveys have been peer-reviewed, and the other comes with the added warning that it was conducted by an EECP provider.
Long COVID, vagus nerve symptoms may overlap
At the European Congress of Clinical Microbiology and Infectious Diseases (ECCMID), scheduled for April 23-26 in Lisbon, Portugal, a team led by researchers in Spain will discuss the role of the vagus nerve in long-term COVID, according to an ECCMID news release.
The vagus nerve runs from the brain into the torso, heart, lungs, intestines and several muscles, including those involved in swallowing. It has a role in heart rate, speech, gag reflex, transfer of food from mouth to stomach, transport of food through the intestines, sweating and other body functions.
The authors said that SARS-CoV-2 infection can lead to prolonged COVID symptoms such as dysphonia (voice problems), dysphagia (difficulty swallowing), dizziness, tachycardia (fast heart rate), orthostatic hypotension (low blood pressure) and diarrhea. Long COVID has been reported to last for months to more than a year.
In the observational study, the researchers evaluated the morphological and functional aspects of the vagus nerve in 348 patients diagnosed with long-term COVID in a Spanish hospital from March to June 2021. Out of the 348, 228 (66%) had at least one symptom attributable to vagus nerve dysfunction (VND).
The ongoing study involved the first 22 participants identified as having at least one VND symptom; 91% of them were women and the median age was 44 years. The most common VND symptoms were diarrhea (73%), tachycardia (59%), dizziness, dysphagia and dysphonia (45% each) and orthostatic hypotension (14%).
Nineteen out of 22 participants (86%) had three or more VND symptoms with a median duration of 14 months. Ultrasound examination showed that at 6 (27%) had changes in the vagus nerve in the neck, including thickening of the nerve and increased echogenicity, indicating mild inflammatory changes.
Thorax ultrasound showed flattened diaphragmatic curves, indicating abnormal breathing, in 10 participants (46%). Ten out of 16 patients (63%) had lower maximal inspiratory pressures, indicating weakness in the muscles involved in breathing.
Thirteen out of 18 patients (72%) had impaired eating and digestive function, including self-reported dysphagia. Among 19 patients assessed for gastrointestinal function, 8 (42%) had reduced ability to move food from the esophagus to the stomach, of which 2 of these 8 reported difficulty swallowing.
Nine out of 19 patients (47%) had gastroesophageal acid reflux, where 4 of these 9 again had problems moving food to the stomach and 3 with hiatal hernia (bulging of the upper stomach through the diaphragm into the chest cavity).
A Voice Handicap Index 30 test (a standard method for measuring voice function) gave abnormal results in 8 out of 17 patients (47%), indicating that 7 of the 8 had dysphonia.
“Our results so far thus point to vagus nerve dysfunction as a central pathophysiological feature of long-term COVID,” the researchers said in the publication.
Improvement of function score, fatigue according to EECP
In a retrospective study to be presented this week at the American College of Cardiology’s (ACC) virtual Cardiovascular Summit, researchers from EECP provider Flow Therapy evaluated the effect of the therapy in 50 COVID-19 survivors, according to an ACC news release. Twenty patients had coronary artery disease (CAD), while 30 did not; the average age was 54 years.
EECP uses astringent and relaxing pneumatic cuffs on the calves, thighs and lower hip area to provide oxygen-rich blood to the heart muscle, brain and the rest of the body. Each session takes 1 hour and patients can review as many as 35 sessions over 7 weeks.
All patients completed the Seattle Angina Questionnaire-7 (SAQ7), Duke Activity Status Index (DASI), PROMIS Fatigue Instrument, Rose Dyspnea Scale (RDS) and the 6-minute walking test (6MWT) before and after the completed 15 to 35 hours of EECP therapy. .
The analysis showed statistically significant improvements in all assessed areas, including 25 more points for health status on SAQ7 (range, 0 to 100), 20 more points for functional capacity on DASI (range, 0 to 58.2), 6 fewer points for fatigue on PROMIS (range, 4 to 20), 50% lower score for shortness of breath on RDS and 178 feet more on 6MWT.
The change from baseline among participants who had long COVID but not CAD was significant for all endpoints, but there was no difference between long COVID patients with or without CAD.
“Emerging data show that long-term COVID is a disease that affects the health of vessels, also known as endothelial function,” said senior author Sachin Shah, PharmD, in the publication. “EECP is a disease-modifying, non-invasive therapy that has previously been shown to improve endothelial function in controlled clinical trials.”
Shah said several study participants were unable to work at the beginning of the study. “Remarkably, at this point, all patients were able to return to work successfully after undergoing treatment,” he said. “These patients also showed improvement in ‘brain fog’, which is a common symptom of prolonged COVID.”
The researchers called for larger studies with a control group that received false therapy to validate their results.