A new systematic review investigating published research on the relationship between COVID-19 and hearing problems is suggesting a number of audio-vestibular symptoms can be associated with the disease. The review found hearing loss, tinnitus and vertigo can all be associated with COVID-19 and the researchers are currently conducting a year-long study to better understand the long-term effects of the disease on hearing.
Kevin Munro and Ibrahim Almufarrij, audiologists from the University of Manchester, first conducted a rapid systematic review into the links between COVID-19 and hearing problems last year. The rapid review looked at the first few months of research and case reports emerging in the early days of the pandemic.
The initial review found audio-vestibular symptoms were rarely reported in early COVID-19 cases, but the researchers did note it was potentially too soon to uncover hearing problems that may only arise over longer periods of time. Now, a year later, the researchers have updated their systematic review finding multiple cases of hearing problems have now been reported.
The new systematic review encompasses 28 case reports and 28 cross-sectional studies. A pooled data analysis revealed 7.6 percent of COVID-19 cases report hearing loss, 7.2 percent report vertigo and 14.8 percent report tinnitus.
Both Munro and Almufarrij are clear in noting the evidence evaluated in their latest review is based on anecdotal reports and self-reported symptoms. So it is not at all clear if this burgeoning association is causally connected.
“It is important not to diagnose audio-vestibular symptoms where they do not exist or where they are coincidental, given the high rates of COVID-19 in the population,” notes Munro in a recent piece for The Conversation. “However, the findings of the review might simply reflect the start of our understanding of this emergent health condition.”
Tinnitus, for example, is a symptom increasingly linked to long COVID. As well as patients reporting COVID-19 exacerbating their pre-existing tinnitus, some believe the disease could initiate the appearance of tinnitus.
Munro suggests tinnitus is a condition that can appear for a number of reasons, from actual ear damage caused by noise or infection, to psychological triggers such as stress and anxiety. So although there may be reasonable hypotheses demonstrating how SARS-CoV-2 could directly damage one’s hearing, he says the current evidence is not of a good enough quality to prove causality.
“It is possible the virus attacks and damages the auditory system,” suggests Munro. “On the other hand, the mental and emotional stress of the pandemic may be the trigger. But we need to be careful when interpreting these findings as it’s not always clear if studies are reporting existing or new symptoms. What is lacking are good-quality studies that compare tinnitus in people with and without COVID-19.”
Hoping to fill that gap in the knowledge, a year-long study is underway tracking COVID-19 patients after discharge from hospital. Munro is leading the study and hopes the work will offer robust insight into the relationship between hearing problems and COVID-19.
The new study was published in the International Journal of Audiology.
Sources: University of Manchester, The Conversation