NERVE damage and a buildup of immune cells in the cornea may be a sign of “long COVID,” a long-term syndrome that emerges in some people after COVID-19 infection, a new study suggests. These preliminary results will need to be verified in a larger group of people with long COVID, or COVID-19 long-haulers, as they’re known, an expert told Live Science. But the findings do hint at something scientists already suspected: Some symptoms of long COVID emerge due to peripheral nerve damage. COVID-19 long-haulers experience a wide range of symptoms, and a large proportion report neurological problems, including headache, numbness in the body, loss of smell and “brain fog,” or trouble thinking and concentrating, Live Science previously reported. This constellation of symptoms hints that long COVID may partly arise from damage to nerve cells in the body, said senior author Dr. Rayaz Malik, a professor of medicine and consultant physician at Weill Cornell Medicine-Qatar in Doha. Specifically, preliminary evidence suggests that long COVID may involve damage to small nerve fibers — thin wires that branch off of specific nerve cells in the body and relay sensory information about pain, temperature and itchiness, among other sensations to the central nervous system. Small-fiber nerve cells also help control involuntary bodily functions, such as heart rate and bowel movements; therefore, damage to these cells can cause a wide array of symptoms. Malik and his colleagues study small-fiber nerve loss in people with diabetes and neurodegenerative diseases like multiple sclerosis; they noticed that people with long COVID appear to share similar symptoms with these patients, so they decided to investigate the potential link. Using a technique called corneal confocal microscopy (CCM), the team took snapshots of nerve cells in the cornea, the transparent layer of the eye that covers the pupil and iris. The team used the non-invasive procedure to count the total number of small-fiber nerve cells in the cornea, while also assessing the length and degree of branching of those fibers. In their work with other conditions, the team has found that, when you find damage in the small-fiber nerves of the cornea, that often indicates that there’s similar damage elsewhere in the body. “This is like a very good barometer, almost, of nerve damage elsewhere,” Malik explained. The new study cannot prove that an immune response caused the observed nerve damage. However, the idea does align with existing evidence that most neurological damage from COVID-19 is caused by inflammation, not by the virus infecting nerve cells directly. (SD-Agencies) | 