COVID-19 and the Ear

For the past two years, the world has been battling the COVID-19 pandemic. While great progress has been made, there is no denying that it is still a global health crisis. Because of its novelty, questions remain about the long-term effects on those who have contracted the virus. This includes the virus’s impact on the auditory and balance systems. Fortunately, research is beginning to appear. To be clear, it is still in the early stages, but it does provide an idea of what to expect.

Hearing Sensitivity

In recent months, I have had patients who felt that their hearing changed after recovering for COVID-19. Did the virus affect their hearing, or was any possible change coincidental? COVID-19 affecting the ear is certainly possible. Other viruses or severe medical conditions have been known to affect the ear, and more significant cases of COVID-19 appear to affect much of the body.

There are multiple ways the virus could affect a person’s hearing. First, it could cause inflammation of the cochlea or auditory nerve. The cochlea in particular is a very delicate organ, which means any slight disturbance could pose a threat. Cardiovascular disturbances associated with the virus could also restrict blood and oxygen flow to the cochlea.

So, what does the science say? It is still not entirely clear. For one, other coronaviruses (e.g., SARS) have not been seen to impact the ear. However, each virus is unique. Current statistics show that about 13% of COVID-19 patients report hearing or balance symptoms lasting up to two months. A systematic review examining studies related to COVID-19 and hearing loss was published in March. It included both case studies (individual patients) and cross-sectional studies. About half of the case studies reported some form of hearing loss as a symptom of COVID-19. Twelve of the cross-sectional also reported hearing loss as a symptom. The authors estimated the prevalence of hearing loss as a result of COVID-19 to be 7.6%.

While the evidence does seem compelling, two considerations should be noted. First, the majority of the studies were deemed to be of Fair, not Good, quality. Second, three of the studies included in the cross-sectional study performed a full test battery on both positive and negative participants. Two of these studies did not find a significant difference in hearing sensitivity between COVID-19 patients and the control group. Thus, more research needs to be done before hearing loss can be definitively listed as a possible symptom of COVID-19.

Tinnitus

Tinnitus is any sound that a person hears that does not originate form a source in their environment. It is often experienced in conjunction with hearing loss, but they can exist independently. The systematic review mentioned previously estimated a prevalence of about 14.8% in COVID-19 patients. However, it was unclear whether the virus caused the tinnitus, or had simply made it worse. It is also possible that the stress of suffering through COVID-19 might be exacerbating the tinnitus. Studies do show that when a person is under more stress, they tend to rate their tinnitus as being more severe or bothersome.

There is a possible physiologic link between the virus and tinnitus. Sensory cells in the cochlea are referred to as hair cells, because of their appearance. There are inner hair cells and outer hair cells. Outer hair cell damage has been shown to have a positive correlation with tinnitus. We can measure outer hair cell status with otoacoustic emissions (OAEs). One study showed that COVID-19 patients had significantly reduced OAEs. Again, this was only one study, but it is worth noting.

Balance

Vertigo and dizziness have also been reported by those with COVID-19. The March study gave a prevalence range of 3.4% to 7.2%. However, the studies do not seem to acknowledge a mechanism for the dizziness. Based on what we know about the balance system in general, it could be a result of the virus attacking the vestibular nerve. Or, it could be simple dehydration or exhaustion. No matter the cause, it does seem to be a possible symptom.

As stated before, more research needs to be done to determine the possible effects of COVID-19 on the audiovestibular system and the likelihood of developing such symptoms. But it does seem something to bear in mind. If you or a loved one develops symptoms following COVID-19, let your audiologist know to help aid understanding and receive the appropriate care. QCBN

By Jeff Lane, Au. D.

Trinity Hearing Center is located at 1330 N. Rim Dr., Suite B in Flagstaff. For more information, visit the website at TrinityHearing.net. Jeff Lane is a doctor of audiology with a passion for improving the lives of others. Dr. Lane may be reached at 928-522-0500 or at audio@trinityhearing.net.