Sudden sensorineural hearing loss (SSNHL) is defined as hearing loss over less than 72 hours, unexplained by other causes. This is considered an otological emergency and requires an immediate referral to the on-call ENT team. The diagnosis is made when someone rapidly loses their hearing, and no conductive cause can be found.
With SSNHL, hearing loss is most often unilateral. It may be permanent or resolve over days to weeks.
Conductive causes of rapid-onset hearing loss (not classed as SSNHL) include:
- Ear wax (or something else blocking the canal)
- Infection (e.g., otitis media or otitis externa)
- Fluid in the middle ear (effusion)
- Eustachian tube dysfunction
- Perforated tympanic membrane
Causes
Most cases (90%) of SSNHL are idiopathic, meaning no specific cause is found.
Other causes of SSNHL include:
- Infection (e.g., meningitis, HIV and mumps)
- Ménière’s disease
- Ototoxic medications
- Multiple sclerosis
- Migraine
- Stroke
- Acoustic neuroma
- Cogan’s syndrome (a rare autoimmune condition causing inflammation of the eyes and inner ear)
Investigations
Audiometry is required to establish the diagnosis. A diagnosis of SSNHL requires a loss of at least 30 decibels in three consecutive frequencies on an audiogram.
MRI or CT head may be used if a stroke or acoustic neuroma are being considered.
Management
The NICE clinical knowledge summaries (updated September 2019) recommend an immediate referral to ENT for assessment within 24 hours for patients presenting with sudden sensorineural hearing loss presenting within 30 days of onset.
Where an underlying cause is found (e.g., infection), treatment can be directed at this.
Idiopathic SSNHL may be treated with steroids under the guidance of the ENT team. Steroids may be:
- Oral
- Intra-tympanic (via an injection of steroids through the tympanic membrane)
Last updated July 2021