The virus may have been eliminated at the time of death or the number of viral copies was below the level of detection.
In a recent study conducted by the National Institutes of Health, researchers routinely looked for spotty damage marks caused by narrowing and leaking cerebral blood vessels in tissue samples from patients who died quickly after contracting coronavirus 2019 (COVID-19). However, they saw no sign of infection with the SARS-CoV-2 virus in the samples collected, potentially suggesting that the damage was not caused by a direct viral attack.
The results, published in the New England Journal of Medicine, adds to the growing body of evidence that a COVID-19 infection has some type of neurological impact. There have been widespread reports of people with the virus experiencing symptoms such as delirium, fatigue, headaches and loss of smell and taste. The disease also caused patients to suffer from other neuropathologies, such as strokes. Although some evidence of the virus has been found, researchers are still trying to understand how COVID-19 affects the brain.
The team responsible for the study analyzed samples of brain tissue from 19 patients who died shortly after contracting the disease, with ages ranging from 5 to 73 years. The time of death ranged from a few hours after obtaining COVID-19 to 2 months. Many of the patients had one or more risk factors, such as obesity, diabetes and other cardiovascular problems.
Using a high-powered magnetic resonance imaging (MRI) scanner 4 to 10 times more sensitive than most common MRI scanners, the researchers examined the olfactory bulbs and brain stem of the tissue samples. They observed that both regions had several light and dark spots, which indicate inflammation and bleeding.
They then examined the samples under a microscope and found that the bright spots showed narrow blood vessels that were leaking protein into the brain, triggering an immune reaction. They also saw that the dark spots had clotted, as well as leaking blood vessels, but no immune response. However, using several methods to detect SARS-CoV-2 genetic material or proteins, they found no evidence of the virus in the tissue samples.
“We found that the brains of patients who contract SARS-CoV-2 infection may be susceptible to microvascular damage to blood vessels. Our results suggest that this may be caused by the body’s inflammatory response to the virus,” Avindra Nath, senior author on study said. “We hope that these results will help doctors understand the full spectrum of problems that patients may experience so that we can come up with better treatments.”