Although recent studies have noted the presence of viral RNA in the brain and cerebrospinal fluid (CSF), it remains unclear where the virus enters and how it is distributed within the brain.
Now, a team from Germany has demonstrated the presence of SARS-CoV-2 RNA and protein in anatomically distinct regions of the nasopharynx and brain. Their autopsy study suggests that SARS-CoV-2 may enter the brain of people through the nose. These findings may help explain some of the neurological symptoms observed in COVID-19 patients and may inform diagnosis and measures to prevent infection… The study assessed olfactory mucosa, its nervous projections, and several defined CNS regions in 33 individuals who died in the context of COVID-19.
The authors also found SARS-CoV-2 spike protein in certain types of cells within the olfactory mucous layer, where it may exploit the proximity of endothelial and nervous tissue to gain entry to the brain. In some patients, SARS-CoV-2 spike protein was found in cells expressing markers of neurons, suggesting that olfactory sensory neurons may be infected, as well as in the brain areas that receive smell and taste signals. SARS-CoV-2 was also found in other areas of the nervous system, including the medulla oblongata—the primary respiratory and cardiovascular control center of the brain.