-An article for doctors in General Practice: How to spot Sudden Sensorineural Hearing Loss (SSHL)
Sudden Sensorineural Hearing Loss (SSHL) is one of the few sensorineural (inner ear) losses known to be reversible in some cases. As an Audiologist, this perks my ears! Because no matter how marvellous the technology, hearing aids can never restore hearing, it can only improve it (that’s if there is any hearing left to improve). But here’s the snag:
SSHL is easily misdiagnosed yet treatment needs to be fast to be effective.
What is SSHL?
SSHL is characterised by a new-onset, unilateral, inner ear hearing loss that develops within 72 hours. Although the prevalence is only 5 to 27 per 100,000 annually, the effects can be very debilitating. Unilateral hearing loss causes difficulty hearing speech clearly in background noise (even with normal hearing in the other ear) and in localising sound.
There appears to be a time window of no more than 2-4 weeks from the onset of deafness during which treatment must be started to be effective. Because of the possibility of improved outcome with steroids, and the narrow window of opportunity for initiating treatment, SSHL should be considered an emergency of the ear.
Aetiology
Although it could be related to acoustic neuroma, trauma, meningitis and several other causes, the majority of SSHL are idiopathic. It sometimes follows a viral infection, such as flu, herpes, or cytomegalovirus or URTI-related viral infections or microvascular obstruction to the blood flow in the cochlea.
Challenges in diagnosis
Unfortunately, SSHL is often misdiagnosed because the symptoms are the same as those found in more common conditions like ear wax build-up or middle ear effusion. Sadly I have seen several patients over my career who presented to their GP with a sudden onset hearing loss and were initially treated with decongestions, only to be diagnosed with an inner ear, permanent hearing loss in later weeks. Many of these patients feel let-down as they were not correctly diagnosed and treated at the onset.
Since a prompt course of steroid treatment may reverse idiopathic SSHL a differential diagnosis is essential. Hence why the humble tuning fork could make you a hero!
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The Weber test can help to distinguish sudden sensorineural hearing loss from middle-ear conductive deafness. Place the base of the tuning fork on top of the head. In middle-ear conductive deafness the sound goes to the affected ear. In sudden sensorineural hearing loss the sound goes to the good ear.
Its that simple. Every surgery should have one! 512Hz is best.
· Alternatively, you could fork out (pardon the pun) a few thousand pound for a Tympanometer. This helpful device measures middle ear functioning to confirm negative middle ear pressure or indicate likely middle ear effusion.
Pure tone audiometry is the gold standard investigation however GP surgeries usually only offer air-conduction screening. Bone conduction testing is essential to confirm the type of loss i.e., conductive vs sensorineural. Therefore, if SSHL is suspected, urgent referral to a specialist is crucial.
Current NICE guidelines: If the hearing loss developed suddenly (over a period of 3 days or less) within the past 30 days, refer immediately (to be seen within 24 hours) to an Ear, Nose and Throat service or an emergency department.
An ENT department will organise investigations and management of remaining hearing loss once the diagnosis is made. Normally an MRI is needed to exclude an acoustic neuroma or other intracranial pathology. Idiopathic sudden sensorineural hearing loss is typically treated with oral steroids.
When seeing patients in your surgery with sudden onset hearing loss, remember that presence of wax doesn’t exclude sudden sensorineural hearing loss and neither does an inflamed looking ear drum.
And whatever you do, please don’t assume that the cause is trivial and the deafness temporary – the truth is you wouldn’t if the patient had lost their sight! Reach for your tuning fork and help to save an ear!
Article by Charlene Coetzee, Audiological Scientist and Hearing Aid Dispenser at Clare Park Hospital
References:
Hillary A. Snapp* and Sebastian A. Ausili; Hearing with One Ear: Consequences and Treatments for Profound Unilateral Hearing Loss, journal of clinical medicine, Apr 2020
Hearing loss in adults: assessment and management NICE guideline [NG98] Published: 21 June 2018
Mr John Graham, consultant ENT surgeon; How not to miss – sudden sensorineural hearing loss, published in Pulse, 3rd March 2013
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