Histomorphological Aspects of SARS-CoV-2-Induced Hippocampal Damage: A Case Series

Abstract

The direct healthcare side effects of the coronavirus disease identified in 2019 caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are immeasurable. Furthermore, the chronic sequels of the disease are yet to be adequately studied and evaluated in the context of the post-infectious specter, referred to as a post-COVID syndrome. One of the most commonly reported such sequel is the so-called "brain fog" -loss of concentration, learning difficulties, and confusion. Herein, we analyzed a series of 50 autopsies of RT-PCR-proven COVID-19. Central nervous system (CNS) samples were obtained in 49 of the cases, with dentate gyrus samples acquired in 9 of them. Histopathological spectrums of hippocampal changes included vascular, degenerative, apoptotic, and necrotic on H&E stains with varying severity. The diffuse nature of the vascular changes, together with the epitheliotropic and especially the endotheliotropic nature of SARS-CoV-2, would suggest that the CNS damage is both hypoxic and vasculotropic. Infected endothelial cells bulge and desquamate (necrosis), disrupting the blood-brain barrier and secondary damage to the neurons by permeating plasma substances.