Middle ear status - structure, function and pathology: A scoping review on middle ear status of COVID-19 positive patients.

BACKGROUND:  The coronavirus disease 2019 (COVID-19) pandemic is the latest public health emergency that has presented challenges globally. Limited evidence exists on the association between COVID-19 and middle ear pathologies, regardless of the respiratory nature of some of the core symptoms. OBJECTIVE:  This scoping review aimed at exploring evidence on the effects of COVID-19 on middle ear functioning as part of symptom mapping and preventive planning for ear and hearing care. METHOD:  Electronic bibliographic databases, including Medline, ProQuest, PubMed, Science Direct, ERIC and Scopus, were searched to identify peer reviewed publications, published in English, between December 2019 and January 2022, related to the effects of COVID-19 on middle ear functioning. The keywords used as MeSH terms included 'middle ear pathology', 'middle ear disorder', 'otitis media', 'hearing loss', 'hearing impairment', 'audiology' and 'COVID-19' or 'coronavirus'. RESULTS:  From eight studies that met the inclusion criteria, the findings revealed that middle ear pathologies occur in this population, with the occurrence ranging from 1.15% to 75%. Tympanic membrane structural changes, otitis media and conductive hearing loss (CHL) were commonly reported. The current findings must be interpreted with caution given that most of the studies reviewed had extremely small sample sizes or were case studies or series, thus limiting generalisability. CONCLUSION:  The findings highlight the value of strategic research planning to collate data during pandemics, ensuring that future studies use appropriate and well-designed methodologies. Trends and patterns of middle ear pathologies in this population must also be established to determine the need for periodic monitoring.

Expression of ACE2, TMPRSS2, and Furin in Mouse Ear Tissue, and the Implications for SARS-CoV-2 Infection.

OBJECTIVES/HYPOTHESIS: Intracellular entry of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) depends on the interaction between its spike protein with the cellular receptor angiotensin-converting enzyme 2 (ACE2) and depends on Furin-mediated spike protein cleavage and spike protein priming by host cell proteases, including transmembrane protease serine 2 (TMPRSS2). As the expression of ACE2, TMPRSS2, and Furin in the middle and inner ear remain unclear, we analyzed the expression of these proteins in mouse ear tissues. STUDY DESIGN: Animal Research. METHODS: We performed immunohistochemical analysis to examine the distribution of ACE2, TMPRSS2, and Furin in the Eustachian tube, middle ear spaces, and cochlea of mice. RESULTS: ACE2 was present in the nucleus of the epithelium of the middle ear and Eustachian tube, as well as in some nuclei of the hair cells in the organ of Corti, in the stria vascularis, and the spiral ganglion cells. ACE2 was also expressed in the cytoplasm of the stria vascularis. TMPRSS2 was expressed in both the nucleus and cytoplasm in the middle spaces, with the expression being stronger in the nucleus in the mucosal epithelium of the middle ear spaces and Eustachian tube. TMPRSS2 was present in the cytoplasm in the organ of Corti and stria vascularis and in the nucleus and cytoplasm in the spiral ganglion. Furin was expressed in the cytoplasm in the middle ear spaces, Eustachian tube, and cochlea. CONCLUSIONS: ACE2, TMPRSS2, and Furin are diffusely present in the Eustachian tube, middle ear spaces, and cochlea, suggesting that these tissues are susceptible to SARS-CoV-2 infection. LEVEL OF EVIDENCE: NA Laryngoscope, 131:E2013-E2017, 2021.