Researchers from the University of Michigan have published a study in the journal Nature Communications describing what constitutes hidden hearing loss in people and what causes it. Long exposure to excessive noise and loss of myelin have been found to be causes of second hearing loss in people. The researchers think this study is a step in the right direction towards finding treatment for people with hidden hearing problems.
According to Gabriel Corfas, director of the Kresge Hearing Research Institute at Michigan Medicine's Department of Otolaryngology (head and neck surgery), a proper diagnosis for hidden hearing loss is critical to knowing the pathogenesis or causes of the problem. Corfas worked with Guoqiang Wan of Nanjing University in China among other scientists to carry out the research. They used mice to study second hearing loss.
Long exposure to excessive noise and loss of myelin cause hidden hearing loss
Using lab mice as the model for their study, the researchers ultimately found that hidden hearing loss is the cause of Guillain-Barre syndrome - caused by Zika virus, among other acute demyelinating disorders. Inducing hearing loss within the auditory nerve of mice through genetic tools, the researchers observed a permanent hearing loss in the mice. The mice never regained hearing even after the myelin regenerated, according to the authors of the study.
The researchers describe hidden or second hearing loss as the condition that occurs when people can't understand words spoken in noisy areas, even though they can hear clearly in quiet places. Corfas made it clear that exposure to loud levels of sound contributes to hidden hearing loss and must be stopped where possible. The reason for this is because loud noises damage the Schwann cells that pick sounds within the ear.
There are currently no treatments for hidden hearing loss
The ultimate goal of the researchers is to understand how to develop treatment drugs for hidden hearing loss. And this is clearly because there are no current treatments for second hearing loss in people. "Our findings should influence the way hidden hearing loss is diagnosed and drive the future of clinical trials searching for a treatment," Corfas said in the published study.