Criteria for establishing an association between Covid-19 and hearing loss.

Dear Editor:

The article entitled “Hearing loss and COVID-19: A note” by Sriwijitalaia W and Wiwanitkit V led me concern about occurrence of hearing loss in patients positive for Covid-19 disease. The authors postulated a relationship between hearing loss and Covid-19 based on an anecdotal case (1.22%) out of 82 Covid-19 patients. We learnt from the article that the patient was an old female. Even they accepted that it was a coincidence. Based on their statement, no recovery was observed. Proposing a relationship between hearing loss and Covid-19 should be based on some criteria. These are:

Covid-19 disease should be diagnosed using PCR or specific antibody titers, preferably Ig M. At least computerized tomography of chest should confirm viral pneumonia with extensive lung involvement bilaterally.

Temporal concordance between the infection and onset of hearing loss should be established. If any, hearing loss is likely to occur at the peak of infection, strong signs of which are high fever and malaise. Probably blood-labyrinth barrier is destroyed at this period. Sometimes, antigen-antibody complex or immune reaction to viral infection may cause sensory hearing loss at the period of downward slope of infection. Therefore, onset of hearing loss within 3 or 4 weeks of Covid-19 disease can be linked to the infection.

Associated symptoms and sign should be sought. These symptoms and signs belong to labyrinthitis or neuritis, e.g. vertigo or dizziness. Strong horizontal nystagmus beating towards healthy side and defective head thrust test with a saccadic correction when the head is rotated towards the lesioned side are expected.

Other reasons that can be counted among the causes of sensory neural hearing loss should be ruled out, e.g., acoustic trauma, noise-induced hearing loss, ototoxicity, head trauma, labyrinth concussion, uncontrolled hypertension, metabolic disease such as diabetes mellitus, hyperlipidemia. Presbycusis and already-diagnosed otologic disease such as Meniere's disease and otosclerosis should also raise doubt establishing an association between the hearing loss and Covid-19 disease. MR should be considered to rule out retro-cochlear lesions such as vestibular schwannoma and multiple sclerosis.

I believe that implementation of these criteria would preclude building biased-high prevalence of hearing loss in Covid-19 positive patients and also establishing a false association between the hearing loss and Covid-19 disease.