A recent study from the MIT and Massachusetts Ear and Eye Institute suggests that novel Coronavirus can infect the inner ear, including the hair cells that play a vital role in ear functions such as hearing and balance. 

This may result in a wide range of symptoms: tinnitus (ear ringing), hearing loss (SNHL or sensorineural hearing loss), dizziness, and vertigo. 

What Were The Findings of The Study?

The research scholars created cellular models by taking human skin cells and reworking them into induced stem cells. After this, they were able to stimulate those cells to differentiate into several types of cells found within the human inner ear: hair cells, supporting cells, nerve fibres, and Schwann cells (that insulate neurons). 

They discovered that the Coronavirus can infect the inner ear’s cells. They also found that the pattern of infection that was seen with human ear tissue was consistent with the symptoms reported by patients.

What is The Mode of Entry of The Virus?

The hair cells and Schwann express certain proteins on their surfaces (ACE2 receptors) and enzymes - furin and transmembrane protease serine 2 (TMPRSS2) that are required for entry, fusion, and multiplication of the SARS-Cov-2 virus into normal cells.

Possible routes for the entry of the virus are:

  • Via the Eustachian tube: from the nose to the ear through the eustachian tube.

  • Via the olfactory nerve fibres: from the nose to the brain and then to the auditory nerve (nerve of hearing).

How Frequently Can This Happen? 

In a study reported in the International Journal of Audiology in March 2021, it was reported that 7.6% of patients with COVID-19 had a loss of hearing, 14.8% experienced a buzzing sound in the ears (tinnitus), and 7.2% had vertigo.

What Are The Possible Symptoms of Long-COVID Syndrome?

  • Persistent tinnitus: This seems to be very common in long-haulers and tends to appear later in the course of COVID-19 infection or after recovery.

  • Loss of hearing: Although a rare complication, some long-haulers have presented with this symptom long after initial infection or recovery. The reason could be either direct or indirect damage of inner ear cells, and studies so far have been inconclusive.

  • Dizziness: This happens mostly on getting up from a sitting position.

What Does This Mean For You? 

If, as a consequence of COVID-19, you are experiencing any of the ear symptoms like tinnitus, hearing loss, or vertigo, you should have yourself checked by a specialist (ENT or Otorhinolaryngologist). 

Your doctor may recommend that you get certain tests done to evaluate your auditory functions, such as Pure Tone Audiogram (PTA), Otoacoustic Emissions (OAE) and auditory brainstem response (ABR).


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