New study finds no evidence of damage to auditory system due to coronavirus infection

After some reports linked COVID-19 with hearing loss, a new study has found no evidence of damage to the auditory system as a result of coronavirus infection. "The possibility of hearing loss has been debated among medical practitioners, with some reporting this symptom in recovered patients," said study author Karen Avraham from Tel Aviv University in Israel.

"The question is whether such hearing loss is caused by damage to the auditory system, or whether it is a temporary symptom caused by fluids clogging the middle ear, as often happens with a common cold," Avraham added. For the study, published in the journal Otology and Neurotology, the research team began to investigate this question during the first wave of the pandemic, when the numbers of patients in Israel were still relatively small.

Participants included eight asymptomatic individuals who had tested positive for COVID-19 and eight healthy volunteers who served as a control group, none of whom reported any previous hearing loss. The study provided for the first time quantitative measures for hearing quality following exposure to the virus. "Our study explored whether COVID-19 can cause permanent neural or sensory damage to the hearing system. We found no evidence for such damage," said co-author Dr. Amiel Dror from the Bar-Ilan University.

The research team measured electrical data from the brainstem to test the entire route of soundwaves through the ear until electric waves are ultimately received in the brain. They also examined the activity of the inner ear hair cells that intensify and tune the sound. "We found no difference between the COVID-19 positive subjects and the control group," Dror said. According to the researchers, it's very important to base our knowledge of the virus upon objective studies and refrain from hasty conclusions. This study proposes that the COVID virus does not cause extensive neurological damage but is rather spotty, mostly affecting the sense of smell. "Moreover, the hearing impairment among some patients is mostly transient and secondary to fluid buildup in the middle ear, as for the common cold, and therefore likely passes once the acute disease is over," the authors wrote.