Tuesday, January 05, 2021
Sars-CoV-2 and rapid death
Covid-19 damages blood vessels in the brain
From Jana Zeh
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Because people with Covid-19 sometimes simply collapse and die, researchers want to know how it happens. They therefore look deep into the brains of Covid-19 victims and find inflammation and bleeding.
Although Covid-19 is primarily a respiratory disease, many infected people also have neurological symptoms. These range from the loss of the sense of smell to headaches and fatal strokes. Researchers in the US wanted to know how this happened. When examining brains, they found that the brain damage is associated with Covid-19 disease, but is not directly triggered by an infection with the virus. This finding contradicts previous research results. The team, led by Avindra Nath from the US National Institute of Neurological Disorders Stroke (NINDS) in Bethesda, Maryland, used particularly powerful magnetic resonance imaging to examine the brain and also analyzed tissue samples.
The researchers saw that the damage is triggered by thinning and leaky blood vessels in the brain. “We found that the brains of patients who become infected with Sars-CoV-2 may be susceptible to microvascular blood vessel damage. Our results suggest this may be caused by the body’s inflammatory response to the virus,” says Nath according to one Message of the NINDS.
The deceased patients were people who contracted Covid-19 between March and July 2020 and were between 5 and 73 years old. The majority had one or more pre-existing conditions that are considered risk factors. They died anywhere from a few hours to two months after showing symptoms. Eight of them were found dead at home or in public. Three patients simply collapsed and suddenly died.
Lots of light and dark spots
The researchers saw a series of light and dark spots on the MRI images of olfactory bulbs and brain stems. The scientists chose these two regions in the brain because there is evidence that they are particularly susceptible to Covid-19. Smelling bulbs control the sense of smell, which is lost on a daily basis in a large proportion of Sars-CoV-2 infected people. Brainstems are responsible for controlling breathing and heart rate.
The spots visible on the MRI scans suggest that there has been both inflammation and bleeding. In order to support the assumptions, these areas were then examined microscopically. The researchers found that the bright spots contained blood vessels whose walls were thinner than normal and in some cases even certain blood proteins had entered the brain. This in turn led to an immune reaction, because the light spots were surrounded by T cells from the blood and the brain’s own immune cells, the so-called microglia. The dark spots, on the other hand, contained clotted blood and leaky blood vessels, but no immune response.
“We were totally surprised,” says Nath, whose Results published in the New England Journal of Medicine. The researchers originally expected damage to be caused by a lack of oxygen. Instead, damage was seen that was associated with strokes and inflammatory diseases. At the same time, there were no signs of Sars-CoV-2 infection in these areas of the brain. Although various methods were used to search for genetic material and proteins of the coronavirus, contrary to other study results, no virus material was found. According to Nath, it is conceivable that the viruses disintegrated after death and were therefore no longer detectable. A number of further investigations are necessary in order to be able to clarify the open questions.
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