Even asymptomatic carriers of the coronavirus (COVID-19) may experience detrimental effects to their cochlear hair cell function, according to a study in the American Journal of Otolaryngology. The American Speech-Language-Hearing Association published a summary of the results on the ASHA Leader Live news magazine.

Researchers from South Valley University in Egypt analyzed 20 confirmed positive cases of patients with COVID-19 who did not present with the known symptoms (cough, shortness of breath, fever or chills, sore throat). They compared this group (ages 20–50, so as to exclude participants with age-related hearing loss) with a control group of non-infected participants. The study measured participants’ hearing ability via transient evoked otoacoustic emissions (TEOAEs) and latencies of vestibular evoked myogenic potentials (VEMPs) over a two-week period.

At the end of two weeks, results showed that for the COVID-infected group, high-frequency pure-tone thresholds as well as the TEOAE amplitudes were significantly worse in the test group, indicating damage to outer ear hair cells.

“This deterioration could be attributed to the damaging effects of the viral infection on the outer hair cells, but the mechanism is still unknown,” writes study author M.W.M. Mustafa of the Otorhinolaryngology Department, Qena Faculty of Medicine, at South Valley University. “The results of the present study also demonstrated that the absence of major symptoms may hide unknown impact on the delicate sensory organs, taking the cochlea as an example.” 

Original Paper: Mustafa MWM. Audiological profile of asymptomatic Covid-19 PCR-positive cases. American Journal of Otolaryngology. 2020;41(3):102483.

Source: ASHA Live Leader, American Journal of Otolaryngology