Brain Damage In COVID-19 Patients

To study how COVID-19 affects a patient's brain, the researchers collected tissue samples from patients who died shortly after contracting the disease. They observed hallmarks of damage caused by thinning and leaky brain blood vessels. However, they saw no signs of the virus SARS-CoV-2 in the tissue samples, which suggests that the damage was not caused by a direct viral attack on the brain. The study conducted by researchers at National Institutes of Health is published in the journal New England Journal of Medicine.

The senior author of the study, Avindra Nath, M.D., clinical director at the NIH's National Institute of Neurological Disorders and Stroke (NINDS) said, “We found that the brains of patients who contract infection from SARS-CoV-2 may be susceptible to microvascular blood vessel damage. Our results suggest that this may be caused by the body's inflammatory response to the virus. We hope these results will help doctors understand the full spectrum of problems patients may suffer so that we can come up with better treatments.”

Even though COVID-19 is a respiratory disease, many patients experience neurological problems like headaches, delirium, cognitive dysfunction, dizziness, fatigue, and loss of the sense of smell. The patients can also suffer from strokes and other neuropathologies.

Several studies have shown that COVID-19 can cause inflammation and blood vessel damage. Only in one study, the researchers found evidence of small amounts of SARS-CoV-2 in some patients' brains. The scientists are still trying to understand how COVID-19 affects the brain.

The Study

The researchers examined brain tissue samples from 19 patients who had died due to COVID-19 between March and July 2020. The age of these patients was between 5 to 73 years old, who had died within a few hours to two months after reporting symptoms and had one or more risk factors, including diabetes, obesity, and cardiovascular disease. Eight of these patients were found dead in public settings or at home and three patients collapsed and died suddenly.

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For the initial study, the researchers used a special, high-powered magnetic resonance imaging (MRI) scanner to examine samples of the olfactory bulbs and brainstems from each patient which are highly susceptible to COVID-19.

The olfactory bulbs control the sense of smell while brainstem controls heart rate and breathing. The scans showed an abundance of bright spots, called hyperintensities indicating inflammation, and dark spots, called hypointensities, that represents bleeding.

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By using the scans as a guide, the researchers examined these spots more closely under a microscope and found that these bright spots contained blood vessels that were thinner than normal and sometimes leaking blood proteins, like fibrinogen, into the brain which triggered an immune reaction. The spots were surrounded by T cells, a type of immune cells from the blood and the brains own immune cells called microglia. The dark spots contained both clotted and leaky blood vessels but no immune response.

Dr Nath said, “We were completely surprised. Originally, we expected to see damage that is caused by a lack of oxygen. Instead, we saw multifocal areas of damage that is usually associated with strokes and neuroinflammatory diseases. So far, our results suggest that the damage we saw may not have been not caused by the SARS-CoV-2 virus directly infecting the brain. In the future, we plan to study how COVID-19 harms the brain's blood vessels and whether that produces some of the short- and long-term symptoms we see in patients."

Source-Medindia