TASS, December 31. Neurophysiologists have found that coronavirus infection often does not penetrate the brain tissue, but contributes to the weakening of the walls of small vessels inside it. As a result, patients are more likely to experience bleeding and strokes. Research results published New England Journal of Medicine.
–
“Our observations show that this is due to inflammatory reactions that are associated with the penetration of the virus into the patient’s body”, – explained one of the authors of the work, researcher at the National Institute of Neurological Disorders and Stroke (USA) Avindra Nat.
A new type of coronavirus (SARS-CoV-2) infects cells not only in the lungs, but also in other organs, for example, inside the nasal mucosa, esophagus, blood vessels and heart. This may explain why many COVID-19 patients lose their sense of smell, suffer from problems with the respiratory system, digestion, and the work of the circulatory system. Also, the virus can enter the human brain and disrupt its work.
In a new study, Nat and colleagues have suggested why some of these problems arise. They studied in detail how the state of the circulatory system of the brain changed in several dozen patients with COVID-19, who died between March and July this year.
All of these patients died very quickly and unexpectedly. The causes of their death were not always related to the penetration of SARS-CoV-2 into their lungs. Initial analysis showed that their deaths were associated with brain damage, but how these damage appeared, scientists do not know.
At first, Nat and his colleagues assumed that the patients died due to the fact that the coronavirus entered their nervous system. Testing this hypothesis, biologists have studied the structure and properties of the olfactory centers and the brain stem – this is where SARS-CoV-2 supposedly gets most often.
The MRI scans showed that there were many foci of inflammation and minor bleeding in both areas of the brain. That is, the walls of small capillaries and other vessels have become permeable to blood and the proteins it contains. Scientists examined slices of these parts of the nervous system in the hope of finding virus particles in them and finding out the cause of the death of vascular and brain cells.
“We expected to see traces of damage from infection and chronic oxygen deprivation. Instead, there was a lot of minor damage to the nervous tissue, which usually occurs after strokes or inflammation of the brain,” explained Nat.
Scientists did not find particles of the virus either in the brain of patients or in its vessels. That is, the capillaries of the brain collapsed not due to infection with SARS-CoV-2, but due to the very high activity of the immune system, which began to attack not only the virus, but also healthy cells of the blood vessels. As a result, “holes” appeared in them, only some of which were filled with blood clots and microglia (protective tissue of the brain).
Scientists hope that observing patients’ health, memory or intellectual abilities that have deteriorated after coronavirus infection will help to understand how long the damage to the blood vessels in the brain persists and to choose a therapy that could prevent their appearance or eliminate them.
–
