As the coronavirus disease (COVID-19) pandemic evolves, the virus's symptoms continue to expand across the human body. Caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the coronavirus infection causes many severe complications in some people, especially those at a higher risk of developing a serious illness.
Transmission electron micrograph of SARS-CoV-2 virus particles, isolated from a patient. Image captured and color-enhanced at the NIAID Integrated Research Facility (IRF) in Fort Detrick, Maryland. Credit: NIAID
Many complications have been reported, including heart disease and prolonged respiratory issues in a group of people called “long-haulers.” Now, a new worrying finding shows that COVID-19 can cause sudden and irreversible hearing loss in patients.
A team of researchers at the University College London report a few cases of hearing loss, diagnosed as sudden-onset sensorineural hearing loss (SSNHL) after being infected with COVID-19.
What is sudden-onset sensorineural hearing loss (SSNHL)?
SSNHL, commonly known as sudden deafness, is an unexplained and rapid loss of hearing all at once or over a few days. It occurs due to a problem with the sensory organs of the inner ear.
SSNHL is also defined as a hearing loss of at least 30 dB in at least three consecutive frequencies that have developed within three days. It is a common condition seen by doctors, with an incidence of 5 to 160 cases per 100,000 people each year.
People affected with the disorder usually experience hearing loss upon waking up in the morning. Accompanying symptoms include the feeling of ear fullness, tinnitus or ringing in the ear, and dizziness.
COVID-19 and SSNHL case study
The study, published in the journal BMJ Case Reports, looks at the case of a 45-year old male with asthma who was admitted to intensive care with COVID-19. He had been intubated for 30 days and suffered from complications, including bilateral pulmonary emboli, ventilator-associated pneumonia, anemia, and pulmonary hypertension.
The patient received drugs, including the antiviral remdesivir and intravenous steroids. He developed hearing loss and tinnitus a week after being extubated and sought medical care from the otolaryngology department.
Other than asthma, he had no other medical conditions before being infected with SARS-CoV-2. When the doctor examined his ear canal, it was unobstructed, and there was no inflammation. The tympanic membranes were intact, but he exhibited left-sided sensorineural hearing loss with a negative Rinne’s test on the side and Weber’s test lateralizing to the opposite ear. Upon having a pure tone audiogram, it was confirmed that he had hearing loss and was subjected to a series of intratympanic steroid injections.
What other studies say
Sensorineural hearing loss has long been studied in the field of otolaryngology, focusing on the optimal route of steroid administration for treatment. But, amid the coronavirus pandemic, the link between COVID-19 and SSNHL has not been well-studied.
To explore the relationship between the two conditions, the team conducted a systematic literature review using EMBASE and PubMed databases between 1950 and 2020. The researchers used keywords such as “hearing loss,” “coronavirus,” “COVID-19,” and “sensorineural hearing loss.” The team landed with three case reports and two case-control studies.
Though a few studies are tackling the link between COVID-19 and SSNHL, tissue studies of patients with SSNHL revealed the loss of hair cells and the supporting cells of the organ of Corti, a part of the inner ear, without inflammatory infiltrate.
“This is the first reported case of sensorineural hearing loss following COVID-19 infection in the UK. Given the widespread presence of the virus in the population and the significant morbidity of hearing loss, it is important to investigate this further,” the team explained.
“This is especially true given the need to promptly identify and treat the hearing loss and the current difficulty in accessing medical services. We suggest that patients are asked about hearing loss in the ITU environments when applicable, and any patient reporting acute hearing loss should be referred to otolaryngology on an emergency basis,” they added.
The sudden SSNHL appears to follow the COVID-19 infection. Just like idiopathic SSNHL, further research is needed to consider the benefit of steroid inflammation.