COVID and the brain: a pathologist’s view
23rd February 2022
A group of pathologists from Saudi Arabia published in the journal “Legal Medicine” a systematic review of current data on autopsies of victims from COVID. Since the process of publishing the article remains slow, the relevance of the research ends on May 2, 2021 and includes 46 studies of suitable quality (out of 1915 initially monitored) with 793 autopsies of patients aged 51-82.9 years at the time of death.
A large-scale massacre was found everywhere, there is no organ or system that would not be affected by the coronavirus. The most common finding is microthrombosis. Strictly speaking, clinicians have been talking about this for a long time, and now pathologists confirm it. Blood clots are observed everywhere – from small vessels of the brain to vessels of lymph nodes. Blood clots were also found in the testicles and prostate. Skeletal muscles show signs of inflammation and necrosis. Viral RNA was found even in the retina of the eyes.
The central nervous system was evaluated in 9 studies. In 36 brains of deceased patients who were examined at autopsy, no visible gross deviations were found, however, microscopic studies revealed widespread microthrombs in the cerebral arteries associated with acute infarction in 30% of the patients. These infarcts had a variable distribution. In one case, a large cerebral artery infarction was detected, while others were small and heterogeneous, located deep. Interestingly, vascular stagnation was disproportionate, since acute microhemorrhagia was observed in the necrotic area of the infarction. Two patients were found to have global oxygen-free trauma, and one had severe hypoxic trauma.
Some researchers attributed the findings in the brain to concomitant diseases, such as hypertension and direct viral damage to neuronal tissue. Sixteen patients in one of the studies demonstrated a disease of small vessels of the brain. A mild hypoxic injury was found in 24 out of 31 patients. However, microscopic examination of inflammatory infiltrate or necrosis of neurons was not detected.
Focal infiltrate of T-lymphocytes, indicating the appearance of focal encephalitis, was also detected in 36 out of 110 cases, but no loss of myelin was observed. The researchers also managed to detect low levels of the number of copies of coronavirus RNA in the brain, but the values in the olfactory bulb were higher than in the brain stem.
Thus, summarizing – the first reviews of brain studies of patients who died from coronavirus (or with coronavirus) show that the brain also gets. First of all, due to microthrombs in the vessels of the brain. However, the virus also enters the brain directly, causing focal encephalitis. But most of the direct action of the virus falls on the olfactory bulbs.
The editorial board, however, wants to say that this is the first review pathanatomic study that includes in its scope the effects of coronavirus on the brain. More autopsies will provide more data – and a better picture of how COVID-19 affects the central nervous system.