We need to talk about how the COVID -19 virus can affect our hearing and balance.
Of all the symptoms caused by the Sars-Cov-2 virus (COVID-19), hearing loss is not one often discussed. This despite the fact that numerous studies show the impact of COVID-19 virus on the audio-vestibular system (e.g., hearing loss, tinnitus and/or vertigo).
The unfortunate consequence of such a contagious disease is no shortage of cases to evaluate and study. According to the World Health Organization in May 2021, there are over 162 million survivors of COVID-19. Symptoms that might not be at the top of the list are still affecting millions of people; a symptom that only affects 5% of those survivors means that there are more than 8 million people who need treatment for that problem. The impact of untreated hearing loss on health, education, and productivity is estimated to cost $750 billion dollars annually (Davis & Hoffman, 2019) and COVID-19 is expected to significantly increase this number.
There are no reports of audio-vestibular symptoms from earlier types of coronaviruses, including Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS); however, these symptoms appear prevalent in those who have been diagnosed with COVID-19. Of patients requiring hospitalization from COVID-19, 13% of patients reported a change in hearing and/or tinnitus lasting weeks after discharge (Almufarrij & Munro, 2020). The most common symptoms (ear aches, vertigo, and dizziness) can last up to 8 weeks (Assaf et al, 2020). If patients experience any such symptoms, they should bring it to the notice of their primary care doctor so that they can be referred to an Otologist and Audiologist for diagnosis and intervention.
There have been several pathophysiological processes that have been proposed regarding how audio- vestibular disorders are caused by COVID-19. Viral involvement can cause cochleitis or neuritis of the inner ear or auditory nerve. Antibodies or T-cells could damage the ear if they mischaracterized inner ear antigens as the virus (Lang et al, 2020). Sudden hearing loss may also be a result of cochlear ischemia or hypoxia, due to the cardiovascular abnormalities associated to COVID-19 (Almufarrij & Munro, 2021). Finally, the virus may trigger immune-mediated inflammation that causes hearing loss, such as inflammation of the meninges (Degen et al, 2020).
A recent systematic review of 30 case studies that investigated hearing loss as a symptom of COVID-19 estimated the prevalence of hearing loss to be 7.6% (Almufarrij & Munro, 2021). With over 162 million survivors, it appears that millions of people may be living with hearing loss after diagnosis. There are numerous case studies that show hearing loss as a symptom of COVID and Almufarrij & Munro's 2021 systematic review of case studies throughout 2020 reported hearing losses of sensorineural, conductive & mixed etiologies that were both bilateral & unilateral, suggesting that hearing care professionals need to be ready for an increase in every type of hearing loss in their patient's ears.
In most studies of audio-vestibular dysfunction & COVID-19, tinnitus is not well-defined but has been described as non-pulsatile, white noise or specific to certain frequencies, intermittent or continuous. Some outlier studies have shown the prevalence of tinnitus as a symptom to be as high as over 60% (Savtale et al, 2021) but Almufarrij & Munro's 2021 systematic review calculated a pooled estimate prevalence of 14.8%. In addition to hearing loss, millions of people are expected to suffer from tinnitus post diagnosis of COVID-19.
Tinnitus often has psychological comorbidities; those who report that their tinnitus is a serious problem are also over 5 times more likely to report anxiety (Bhatt et al, 2017). A disease that has continues to take its toll on our stress and anxiety levels has the potential to heighten the negative effects of tinnitus for people who have not even contracted the virus! Even worse, tinnitus sufferers document less hours of sleep per night and miss more days of work (Bhatt et al, 2017), adding to the economic toll of the pandemic.
Unfortunately, COVID-19's effect on the audio-vestibular also includes another debilitating symptom: dizziness. Symptoms of dizziness and rotary vertigo seem to be prevalent in patients infected with COVID and can persist throughout recovery. There have been numerous of reports of vertigo in the literature and its prevalence appears to be as low as 3.4% to as high as 7.2% of the population, depending on whether dizziness was also included in conjunction with vertigo as a reported symptom on the study (Almufarrij & Munro, 2021).
Experimental life-saving treatments have the potential to add to the insult to the audio-vestibular system. Treatments using ototoxic medications such as hydroxychloroquine and azithromycin have been used to treat COVID-19 without proven success (Prayuenyong et al, 2020). While azithromycin itself has not been a large concern for ototoxicity, it is documented to cause irreversible sensorineural hearing loss at high dosages (Brown. et al, 1997; Ress. et al, 2000) and experimentation with this drug has the potential to increase the rate of hearing loss in the population.
Fortunately, our knowledge of the audio-vestibular system continues to grow alongside with our understanding of COVID-19. Our ability to treat these symptoms involve science that has been around for decades. As we continue to live with this virus, we will be able to mitigate the negative consequences. Through determination and resilience, we can learn and cope together.
Dr. Sugata Bhattacharjee, Au.D., CCC-A, FAAA. Doctor of Audiology is the Chief Audiologist at Hearing Center of Southern, Connecticut, Past International Chair American Academy of Audiology and Editorial Board Member The Hearing Review Journal. (Affiliation Starkey Laboratories and Nazareth Hearcare). E-mail: drsugata@hotmail.com, Twitter: @drsugata
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