A patient came to see me a few years ago who had woken up one morning with almost no hearing in his left ear. No pain, no recent illness, nothing he could point to as a cause. He had assumed it would settle and had waited two days before coming in. He was lucky because we caught it just in time, started treatment, and his hearing recovered. Had he waited much longer, the outcome might have been very different.
What he had was sudden sensorineural hearing loss, which is a medical emergency. There are two main types of hearing loss and the distinction between them matters.
Conductive hearing loss occurs when sound cannot travel properly through the outer or middle ear to reach the inner ear. Common causes include earwax blockage, ear infections, fluid behind the eardrum, a perforated eardrum, or problems with the tiny bones of the middle ear. This type is usually treatable by addressing the underlying cause which allows the hearing to return.
By contrast, sensorineural hearing loss involves damage to the inner ear itself or the auditory nerve. Causes include age-related degeneration, noise exposure, certain medications, or tumours such as an acoustic neuroma. This type is often permanent.
The emergency version is sudden sensorineural hearing loss where hearing deteriorates rapidly over hours to days. There is a window of approximately 72 hours to start high-dose steroid treatment to try to preserve hearing. After that window closes, outcomes are significantly worse. This is why prompt assessment matters so much, and why waiting to see if it resolves on its own is a gamble not worth taking.
There is a simple test that can give you a rough sense of which type you might have. Close both ears firmly with your fingers and hum. If the hum sounds louder in the ear with hearing loss, this suggests conductive hearing loss — sound is being trapped in the ear canal and middle ear, enhancing bone conduction. If the hum sounds louder in the good ear, that points toward sensorineural hearing loss, where the inner ear or nerve on the affected side cannot process sound properly even when it is conducted through bone. Equal in both ears but still struggling? Something else may be going on, and it warrants assessment either way.
The warning signs that need same-day or urgent review are: sudden hearing loss in one or both ears, hearing loss accompanied by dizziness or vertigo, hearing loss with a severe headache, hearing loss following a head injury, or hearing loss alongside any facial weakness. Gradual hearing loss is less urgent but still worth investigating. Your GP can examine your ears, remove wax if needed, and refer you to audiology for formal testing.
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References:
1. Stachler RJ, et al. Clinical Practice Guideline: Sudden Hearing Loss. Otolaryngol Head Neck Surg. 2012;146(3 Suppl):S1–35.
2. Schreiber BE, et al. Sudden sensorineural hearing loss. Lancet. 2010;375(9721):1203–11.
3. Kuhn M, et al. Sudden sensorineural hearing loss: a review of diagnosis, treatment, and prognosis. Trends Amplif. 2011;15(3):91–105.