Sudden hearing loss could be a new consequence of Covid-19 infection. Several cases have been reported and scientists are now trying to understand the causes.
The consequences of Covid-19 are definitely becoming more and more bizarre. After the loss of smell, persistent fatigue, cardiac or neurological side effects, hearing problems also seem to be a concern. A study published in BMJ magazine reports the case of a 45-year-old man who suddenly became deaf in one ear after a severe form of Covid-19.
The patient was intubated for 30 days and treated with Remdesivir, intravenous steroids, and plasma. One week after his release from intensive care he developed tinnitus on the left side, followed by sudden hearing loss. No other cause for the deafness was found(damage to the eardrum or inflammation) and therefore it was concluded that it was SARS-Cov-2 related.
Several other cases of sudden hearing loss related to the coronavirus have been reported in the scientific literature. In June, for example, an asymptomatic Egyptian man suffered sudden hearing loss, reports the International Journal of Infectious Diseases.
In a study published in the International Journal of Audiology in July, 13.2% of patients who tested positive for coronavirus reported that they experienced a change in their hearing or tinnitus after diagnosis of Covid-19. However, this symptom is not among those officially registered by the WHO or other health authorities.
Hearing Loss and Viral Infections
These cases are not surprising as it is known that viral infections can lead to neurological manifestations such as anosmia, facial paralysis, and hearing loss. Three mechanisms may be involved: neuritis, which is caused by infection of the cochlear nerve, infection of the cochlea and perilymphatic tissue, and the stress resulting from the response of inner ear antigens.
The authors of the study, published in the International Journal of Infectious Diseases, added: “Animal studies with different viruses also report hearing loss caused by direct involvement of inner ear structures or indirectly by cerebrospinal fluid in the brain”. Stress and anxiety are also factors that can lead to sudden hearing loss, and several studies have reported on them.
The extent to which the virus can directly damage the ear has not been proven. However, the middle ear cells (between the outer and inner ear) do harbor ACE-2 receptors, the receptors to which SARS-Cov-2 binds. “It is, therefore, possible that the direct entry of the virus into the cochlea can trigger an inflammatory response and an increase in cytokines (inflammatory substances released by immune cells),” noted the authors of the study.
On CNN, the Professor of Otolaryngology at Johns Hopkins Medicine presented another hypothesis: “It is known that the coronavirus causes blood clots that clog the arteries. Since the capillaries in the ear are the thinnest in the human body, it would not take much to clog them.
High-dose oral steroids have improved hearing among those affected.
- Could sudden sensorineural hearing loss be the sole manifestation of COVID-19? An investigation into SARS-COV-2 in the etiology of sudden sensorineural hearing loss
- Sudden irreversible hearing loss post COVID-19
- Persistent self-reported changes in hearing and tinnitus in post-hospitalization COVID-19 cases
- Mom loses hearing in one ear after mild Covid-19 infection