After olfactory function loss, meaning losing the ability to smell, researchers in the U.K. have found that hearing loss and other auditory problems may also be strongly associated with the coronavirus.
The researchers found 56 studies that identified an association between COVID-19 and auditory and vestibular problems in mounting evidence. They pooled data from 24 of the studies to estimate that the prevalence of hearing loss was 7.6%, tinnitus was 14.8% and vertigo was 7.2%.
The vestibular system includes the parts of the inner ear and brain that process the sensory information involved with controlling balance and eye movements.
However, the team, who followed up their review carried out a year ago, described the quality of the studies as fair. Their data primarily used self-reported questionnaires or medical records to obtain COVID-19-related symptoms, rather than the more scientifically reliable hearing tests.
"There is an urgent need for a carefully conducted clinical and diagnostic study to understand the long-term effects of COVID-19 on the auditory system," said Kevin Munro, professor of audiology at the University of Manchester and Manchester Biomedical Research Centre (BRC) hearing health lead.
"It is also well-known that viruses such as measles, mumps and meningitis can cause hearing loss; little is understood about the auditory effects of the Sars-CoV-2 virus.
"Though this review provides further evidence for an association, the studies we looked at were of varying quality so more work needs to be done."
Munro is leading a yearlong U.K. study to investigate the possible long-term impact of coronavirus on hearing among people who have been previously treated in a hospital for the virus.
His team hopes to accurately estimate the number and severity of COVID-19 related hearing disorders in the U.K. and discover what parts of the auditory system might be affected. The new study, published in the International Journal of Audiology, was funded by the NIHR Manchester Biomedical Research Centre.
