The Clinical Features And Mechanisms Of COVID-19-related Hearing Loss

Background: Severe acute respiratory syndrome coronavirus 2(SARS-Cov-2)is a highly lethal coronavirus that endangers human life and health.The WHO(World Health Organization,WHO)declared that SARS-Cov-2-induced serious disease was named as Coronavirus disease 2019(COVID-19).SARS-Cov-2 is mainly transmitted through respiratory droplets.COVID-19 can result in damages to many organs and systems of human body.There are different clinical symptoms.The previous study reported that olfactory and taste disorders are the common symptoms or even the only symptoms in the early stage of the onset of COVID-19.Moreover,olfactory and taste disorders can be used as the early warning symptoms for asymptomatic infection during COVID-19 pandemic.It seems that the auditory system is far away from the respiratory tract,but COVID-19-related hearing loss has also been reported by scholars.Early detection and intervention is very important for patients with viral-induced deafness.COVID-19-related hearing loss has a great impact on individuals,society,and epidemic prevention and control.Moreover,COVID-19-related hearing loss seriously affects the necessary communication,and treatment and rehabilitation especially in the case of universal wearing masks.So far,there are still some problems to be investigated in the relationship between COVID-19 and hearing loss.Objective: To explore the clinical classification and characteristics,pathogenesis,early warning function,treatment and health services of COVID-19-related hearing loss by analyzing the published literature on COVID-19-related hearing loss,and provide the basis for the clinical practice during the COVID-19 pandemic.Methods: The key words included "COVID 19","SARS-Co V-2",“hearing” and "Hearing loss".The literatures were searched in Chinese Academic Journal Full-text Database(CNKI),Wanfang,EMBASE and Pub Med databases,and the deadline is January 15,2021.Moreover,the relevant inclusion and exclusion criteria were established,and the related literatures were screened.Finally,the literatures on COVID-19-related hearing loss were analyzed for the clinical classification and characteristics,pathogenesis,early warning function,treatment and health services.Results: 1.There was few literature on the clinical research and mechanism of COVID-19-related hearing loss.2.According to the inclusion criteria,the literatures included 9 case reports,1 case group report,1 retrospective study,2 cross-sectional surveys,2research letters to editors,2 clinical surveys,1 questionnaire survey,1 annotation,and 3 national guidelines or expert suggestions.3.The types of COVID-19-related hearing loss included conductive hearing loss,and sensorineural hearing loss.The sudden sensorineural hearing loss(SSNHL)seems to be the most common type at present.Moreover,there are no reports about drug-induced hearing loss by hydroxychloroquine and chloroquine.There is 1confirmed case with vertigo and congenital inner ear disease.4.There are few literatures on the mechanism of COVID-19-related hearing loss.The mechanism of SARS-Cov-2 infection was speculated primarily based on the neurophilic characteristics,and clinical studies of other coronaviruses.It has been well-known that SARS-Cov-2 infection depended on angiotensin converting enzyme2(ACE2).Furthermore,The central and peripheral auditory system damage maybe result from the direct damage to cochlear hair cells,inflammation,cytokine storm,immune dysfunction,and other microcirculation disorders by SARS-Cov-2.5.Hearing loss may be the precursor of SARS-Cov-2 infection in some patients.10 articles reported hearing loss or aggravation of primary hearing loss in patients after COVID-19 infection.6.1 article reported that the threshold of 4000,6000 and 8000 Hz increased by high-frequency pure tone audiometry,and the amplitude of transient evoked otoacoustic emission(TEOAE)decreased at high frequency in the early stage of asymptomatic patient.7.There were 26 literatures on treatment,including 17 drug treatment studies and 1 cochlear implant treatment report.Oral or intratympanic corticosteroids or the combination of the two methods could improve the hearing of patients(5/7)with COVID-19-related SSNHL.At the same time,otitis media cases(9/10)could be improved or cured by outpatient treatment.8.There were 13 articles about health care of patients with hearing loss,and 2 articles about the timing of otology surgery during the COVID-19 epidemic.Conclusion: 1.COVID-19-related hearing loss can be mild or severe,unilateral or bilateral,and sensorineural or conductive.UP to now,there is no literature on drug-induced hearing loss caused by hydroxychloroquine and chloroquine,but doctors must be alert to the drug-induced hearing loss.2.SSNHL may be the most common type of COVID-19-related hearing loss.It is necessary to clarify whether SARS-Cov-2 result in the worse of primary hearing loss.3.Hearing loss is an early symptom of COVID-19 infection,which may be used as a predictor of positive detection in some asymptomatic patients.4.The mechanism of COVID-19-related hearing loss may include direct damage of SARS-Cov-2 to inner ear structure,immune-mediated inflammation,thrombosis and so on.Furthermore,high-frequency pure tone audiometry and TEOAE can early detect asymptomatic cases.5.Oral or intratympanic corticosteroids or combined treatment can improve the hearing of most patients with COVID-19-related SSNHL.Patients with COVID-19-related otitis media can be improved or cured by outpatient treatment.6.The medical and health institutions should provide basic health care services for patients with hearing loss,and the timing of otology surgery should be carefully selected during the COVID-19 pandemic.7.The acute and long-term effects and mechanisms of COVID-19 infection on auditory system need to be further clarified through high-quality investigations.