Relationship between COVID-19 patients and cerebrovascular damage and inflammation
In a study investigating how COVID-19 causes effects on the brain, researchers consistently found features of damage caused by thinning and leakage of cerebral blood vessels in tissue samples from patients who died shortly after contracting the disease.
There were no signs of SARS-CoV-2 in the tissue samples, suggesting that the damage was not caused by a direct viral attack on the brain.
The results were published in the New England Journal of Medicine.
In this study.
Researchers had conducted detailed examinations of brain tissue samples from 19 patients who were infected with COVID-19 between March and July 2020 and later died.The patients ranged in age from 5 to 73 years, and died within hours to two months of reporting symptoms.
Many patients had one or more risk factors, such as diabetes, obesity, or cardiovascular disease.
Initially, a special high-powered magnetic resonance imaging (MRI) scanner, which is four to ten times more sensitive than most MRI scanners, was used to examine samples of each patient's olfactory bulb and brain stem.
These areas are thought to be highly susceptible to COVID-19.
The olfactory bulb controls the sense of smell, and the brainstem is where respiration and heart rate are regulated. The scans revealed that both regions are rich in bright spots called hyperintensities, which often indicate inflammation, and dark spots called hypointensities, which represent bleeding.
Using the scans as a guide, the researchers examined the spots in more detail under the microscope.
It was discovered that the bright spots contained blood vessels that were thinner than normal and could leak blood proteins, such as fibrinogen, into the brain, which appeared to trigger an immune response.
The spots were surrounded by T cells from the blood and the brain's own immune cells called microglia. In contrast, the dark spots contained both coagulated and leaky blood vessels, but no immune response.
We were completely surprised. Initially, damage due to lack of oxygen was expected. Instead, we saw multiple areas of damage usually associated with stroke and neuroinflammatory diseases," said Dr. Nath.
Dr. Nath said.
Finally, the researchers found no signs of infection in the brain tissue samples, despite using several methods to detect genetic material or proteins from SARS-CoV-2.
So far, our results suggest that the damage we saw may not have been caused by the SARS-CoV-2 virus directly infecting the brain," said Dr. Nath.
Dr. Nath stated.
Lee MH, Perl DP, Nair G, Li W, Maric D, Murray H, Dodd SJ, Koretsky AP, Watts JA, Cheung V, Masliah E, Horkayne-Szakaly I, Jones R, Stram MN, Moncur J, Hefti M Folkerth RD, Nath A. Microvascular injury in the brain of patients with COVID-19. New England Journal of Medicine, December 30, 2020 DOI: 10.1056 / NEJMc2033369.
Summary.
Although multiple complications were reported due to the infection, this study showed that there was no evidence of infection in the damaged tissue.
We do not know if this will be proven or overturned by future research, but there is no doubt that each organ is affected by the infection, but there may be no link between the infected cells and the symptomatic organ.
