By Antonella Macerollo
For January 2021, we have selected: Matschke et al. Neuropathology of patients with COVID-19 in Germany: a post-mortem case series. Lancet Neurol 2020; 19:919-929. doi: 10.1016/S1474-4422(20)30308-2.
It has been reported by several studies over the last few months that COVID-19 may be associated with neurological symptoms. However, there has been a lack of knowledge about the pathological mechanisms which might underlie neurological complications caused by this virus. Our paper of the month adds some clarity to this aspect. The authors investigating brain tissue of 43 patients who died from COVID-19 between March 13 and April 24, 2020, in Hamburg, Germany. Patients were aged between 51 years and 94 years (median 76 years [IQR 70–86]). The authors explored the following characteristics: glial responses, inflammatory changes, and the presence of the virus in the central nervous system (CNS).
Inclusion criteria were a positive test for COVID-19 by quantitative RT-PCR (qRT-PCR) and availability of adequate samples.
The following changes were found: fresh territorial ischaemic lesions (6; 14%) and astrogliosis in all assessed regions (37; 86%).
The brainstem and cerebellum were particularly involved with activation of microglia and infiltration by cytotoxic T lymphocytes. Meningeal cytotoxic T lymphocyte infiltration was seen in 34 (79%) patients. 53% of patients were found to have COVID-19 in the brain with viral proteins in cranial nerves originating from the lower brainstem and in isolated cells of the brainstem. Importantly, the presence of the virus in the CNS was not associated with the severity of neuropathological changes. This finding suggests that it is not the viral load per se that triggers brain neuroinflammation but just the presence of the virus. On the other hand, there were no specific neuropathological changes caused directly by the virus. Further larger multicentre neuropathological studies are necessary to improve our knowledge and consequentially inform management of neurological complications of this virus.