COVID-19 and long COVID may be linked to impaired sensory neurons, a recent study Massachusetts Institute of Technology (MIT) study finds.
Sensory neurons are responsible for smell, taste, touch, pain, and changes in temperature. Damage to them may lead to impaired senses.
Surprisingly, the study found that infected neurons released viral proteins like the spike protein and nucleocapsid proteins rather than the virus releasing them.
Not all neurons were infected. All lab-made neurons were exposed to the Wuhan, delta, and omicron strains, but only up to 30 percent of the neurons were infected, with the omicron variant having the lowest infection rate.
Some doctors have suspected that the sensory problems, such as lost or impaired smell, taste, and hearing, and muscle pains, numbness, burning, and electrical shock sensations, seen in long COVID and vaccine-injured patients are due to the spike proteins on the COVID-19 virus’ surface. The mRNA and adenovirus vaccines similarly instruct the body to produce spike proteins.
The MIT study shows what “our clinical gut instinct” tells us is the cause of symptoms, neurologist Dr. Diane Counce told sources.
Other factors may also be at play.
A common driver is inflammation. Inflammation occurs as immune cells clear out viruses and their proteins. Yet a constant state of inflammation is not viable for normal neural function, and neurons can become hyperreactive and damaged.
Some patients may also develop mast cell activation syndrome (MCAS). In MCAS, patients become highly sensitive to any change in the environment. The histamine released in such a scenario irritates the nerves, causing neuropathic pain and itching. Swelling and mucus production due to this allergic response can also impair the senses if sensory neurons are near the site of histamine release.
Another increasingly recognized driver is microclotting.
“The nerves form a webbing around the blood vessels … If you have clotting, then you’re not feeding the nerves correctly,” Dr. Counce said, adding that this could cause something close to “infarcts in the nerves.”
Sensory problems from microclotting often manifest alongside other symptoms, including chest pain, palpitations, and shortness of breath.
These mechanisms can be affected simultaneously and overlap; therefore, several different therapeutics must often be prescribed to manage all the different systems, said internal medicine physician Dr. Keith Berkowitz.