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. 2022 Jun;33(2):141-146.
doi: 10.1016/j.otot.2022.04.010. Epub 2022 Apr 29.

Olfactory dysfunction and COVID-19

Rhea Choi  1 , Rupali Gupta  1 , John B Finlay  2 , Bradley J Goldstein  1   3
Affiliations

Olfactory dysfunction and COVID-19

Rhea Choi et al. Oper Tech Otolayngol Head Neck Surg. 2022 Jun.

Abstract

Here, we provide an overview of olfactory dysfunction associated with COVID-19. We provide background regarding the organization and function of the peripheral olfactory system. A review of the relevant literature on anosmia and parosmia due to infection with SARS-CoV-2, the virus causing COVID-19, is provided. Specific attention is focused on possible mechanisms by which the virus may interact with and damage the cell populations of peripheral olfactory system. Evidence from human studies as well as animal models is considered. Finally, we discuss current recommendations for evaluation and management of patients with persistent post-COVID olfactory dysfunction, as well as possible future research directions.

Keywords: COVID-19; Olfaction; Olfactory dysfunction.

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Conflict of interest statement

The author declare no conflicts of interest.

Figures

Fig. 1
Fig. 1
SARS-CoV-2 infects olfactory sustentacular cells. (A) Organization of the olfactory epithelium, lining the superior portions of the nasal cavity. Human olfactory biopsy stained with antibofu TUJ1 (green) outling olfactory sensory neurons (OSNs); sustentacular cell (SUS) nuclei are located superficial to OSNs, near the nasal airspace. Nuclei are labeled in blue with DAPI; Bar approximately 10 μm. (B) Schematic showing olfactory cell populations, including sustentacular cells (SUS), olfactory sensory neurons (OSNs), globose basal cells (GBCs), horizontal basal cells (HBCs), microvillar cells (MV), immune cells (ICs), and Bowman's glands (BG). (C) The SARS-CoV-2 spike protein binds to the ACE2 surface receptor on sustentacular cells, permitting viral entry; cleavage of the spike protein likely occurs via the cell surface protease TMPRSS2 (not shown). (Color version of figure is available online.)
Fig. 2
Fig. 2
Possible mechanisms of olfactory loss due to SARS-CoV-2 infection. (A) Following viral infection of sustentacular cells, olfactory loss may occur due to sustentacular cell death, impairing neuronal function. (B) Sensory loss could also occur due to immune cell response causing inflammation, neuronal dysfunction, or neuronal death and impaired epithelial reconstitution due to chronic inflammation. (Color version of figure is available online.)
See this image and copyright information in PMC

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