Sudden Sensorineural Hearing Loss

Sudden sensorineural hearing loss should be considered an emergency as it is a loss of a special sense. No one would hesitate to investigate a patient who presents with loss of vision from one eye – so the same urgency should be placed on sudden sensorineural hearing loss.

This condition normally presents with a patient who simply says they have lost the ability to hear from one ear with no obvious predisposing cause or associated symptoms. The definition is sensorineural hearing loss of greater than 30dB or more in at least three contiguous frequencies in less than three days.

The incidence is 20 cases per 100,00 per year with a peak age in the 50th decade.

The history includes loss of hearing normally complete within a few hours. No history of pain, trauma, discharge etc.

In these situations it is important that patients are tested to see what type of hearing loss they have. Tuning fork tests would differentiate between conductive and sensorineural hearing loss. If you don’t have a tuning fork you could scratch the patient’s front teeth with your nail (which would give you a very basic Webers test ). You could also just ask if when the patient speaks they can hear their voice more in the affected ear (conductive loss) or only in the good ear (sensorineural loss). Obviously a hearing test would be ideal if you have access to one.

Examination of the ear normally shows a completely normal ear with no obvious cause of hearing loss.

Causes

Unfortunately this is never clear but most people consider three main candidates:
• Vascular insufficiency of the cochlea and / or nerve.
• Viral infection of the cochlea and / or nerve.
• Inflammation of the cochlea and / or nerve.

The prognosis is typically 30% resolve completely, 30% are left with reduced hearing, 30% get worse. This is true with and without treatment. It seems nothing has been shown to improve the clinical outcome of this condition. For this reason some departments will treat with everything that might help, and some departments will just send the patient home after ruling out the other causes.

Treatment

Steroids

A Cochrane systematic review (of two suitable studies) found no benefit with steroid treatment. Even so steroid treatment is commonly prescribed

Antiviral drugs

Again level 1 evidence from 4 trials suggest that there is no statistical improvement shown in patients treated with acyclovir or valacyclovir with or without steroids.

Carbogen

- Gaseous mixture of 95% oxygen and 5% carbon dioxide - is meant to be inhaled for 5 mins of every waking hour for 24-48 hours. Inhaling carbon dioxide results in vasodilation which might help a vascular insufficiency condition. Cinnamon et al in 2001 showed no benefit of carbogen in his trial.

Hyperbaric oxygen therapy

A Cochrane systematic review showed that there is actually some statistical improvement in the hearing of patients undergoing this treatment however this improvement was not functionally clinically significant – therefore one cannot justify the use of this treatment modality.

Plasma expanders, vasodilators such as prostaglandin E1 and other ideas have all been shown to have no benefit.


Most of the trials are of poor quality due to low patient numbers so evidence may become about in the future. In the meantime treatment of these patients is directly by individual departments and sometimes individual consultants. Most of these patients are followed up no matter what the treatment given and if associated with tinnitus and / or vertigo then most consider MRI to look for an acoustic neuroma.

Further Reading

eMedicine - Sudden Hearing Loss - by Neeraj N Mathur, MBBS, MS

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