Study reveals brain damage in patients with COVID-19

In a new study, scientists at the National Institutes of Health have performed extensive brain scans of patients with COVID-19. They spotted signs of damage from thinning and leaking brain blood vessels in tissue samples from patients who died shortly after contracting the disease.

The surprising fact was that there was no sign of SARS-CoV-2 in the tissue samples. This indicates that the damage was not caused by a direct viral attack on the brain.

The brains of patients who become infected with SARS-CoV-2 may be susceptible to microvascular damage to the blood vessels. The results suggest that it could be caused by the body’s inflammatory response to the virus.

Avindra Nath, MD, clinical director of the NIH National Institute of Neurological Disorders and Stroke (NINDS) and lead author of the study, said: “We hope these results will help physicians understand the full spectrum of problems patients may suffer so that we can provide better treatments.”

COVID-19 is primarily a respiratory disease, but it also affects the brain. Patients often experience neurological problems, including headaches, delirium, cognitive dysfunction, dizziness, fatigue, and loss of smell. The disease can also cause strokes and other neuropathologies.

Several studies have shown that the disease can cause inflammation and damage to blood vessels. In one of these studies, scientists found evidence of small amounts of SARS-CoV-2 in the brains of some patients. Nevertheless, scientists are still trying to understand how the disease affects the brain.

This new study was conducted on brain tissue samples from 19 patients who died after suffering from COVID-19 between March and July 2020. Samples from 16 of the patients were provided by the Office of the Chief Medical Examiner in New York City, while the pathology department provided the other 3 cases to the University of Iowa College of Medicine, Iowa City.

The patients died at a wide variety of ages, from 5 to 73 years old. They died within hours to two months of reporting symptoms. Many patients had one or more risk factors, including diabetes, obesity, and cardiovascular disease. Eight of the patients were found dead at home or in public places. Three other patients collapsed and died suddenly.

For the study, a high power magnetic resonance imaging (MRI) scanner was used. The scanner is 4 to 10 times more sensitive than most MRI scanners.

Using the scanner, the scientists examined samples of the olfactory bulbs and brainstems of each patient. These regions are believed to be very susceptible to COVID-19. The scans found that both regions had an abundance of bright spots, called hyperintensities, which often indicate inflammation, and dark spots, called hypointensities, represent bleeding.

Scientists then used the scans as a guide to examine the spots more closely under a microscope. They found that the bright spots contained thinner-than-normal blood vessels, and blood proteins, like fibrinogen, sometimes leaked into the brain.

It seems to trigger an immune reaction. The spots were surrounded by T cells in the blood and immune cells in the brain called microglia. In contrast, the dark spots contained both coagulated and leaky blood vessels, but no immune response.

Dr Nath said, “We were completely surprised. We originally expected to see the damage from a lack of oxygen. Instead, we saw multifocal areas of damage typically associated with stroke and neuro-inflammatory disease. “

“So far, our results suggest that the damage we have seen may not have been caused by the SARS-CoV-2 virus directly infecting the brain. Going forward, we plan to study how COVID-19 harms blood vessels in the brain, and whether it produces some of the short- and long-term symptoms we see in patients.

Journal reference:
  1. Myoung-Hwa Lee et al., Microvascular Injury in the Brains of Patients with Covid-19, New England Journal of Medicine (2020). DOI: 10.1056 / NEJMc2033369

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