Describe autoimmune inner ear disease.

Nature and Presentation

• Autoimmune inner ear disease (AIED) is immune-mediated damage to the inner ear, producing rapidly progressive, bilateral, asymmetric sensorineural hearing loss over weeks to months.
• It is important because it is one of the very few sensorineural losses that is treatable.
• The defining clinical feature IS the time course — loss progressing over weeks to months: too fast for presbycusis, too slow for sudden sensorineural loss, and bilateral. That intermediate tempo is what should raise the suspicion
• Primary (organ-specific) AIED affects the ear alone; secondary AIED occurs as part of a systemic autoimmune disease
• The systemic associations to look for — granulomatosis with polyangiitis (Wegener), in which ear involvement is common and may be the presentation; COGAN syndrome — the combination of interstitial keratitis with audiovestibular symptoms.
• Features — bilateral but asymmetric sensorineural loss.
• Suspect it particularly where there is bilateral Meniere-like disease, sudden sensorineural loss that fails to recover or recurs, or hearing loss with systemic symptoms — arthralgia, rash, fever, weight loss, eye inflammation or renal disease
• Investigation — there is NO single diagnostic test.
• Serial pure tone audiometry is the key measure, documenting the progression and the response to treatment
• Blood tests — ESR and CRP; ANA, rheumatoid factor, ANCA (for granulomatosis with polyangiitis); complement; and syphilis serology.
• Anti-heat shock protein 70 antibody was proposed as a marker and correlates with steroid responsiveness, but is neither sensitive nor specific enough for routine use
• MRI to exclude a vestibular schwannoma and to look for labyrinthine enhancement
• Treatment — high-dose oral corticosteroid (prednisolone 1 mg/kg) for at least 4 weeks is both the treatment and the diagnostic trial; a response supports the diagnosis, and the dose is then tapered slowly
• Intratympanic steroid as an adjunct or where systemic steroid is contraindicated
• Steroid-sparing agents for relapsing or steroid-dependent disease — methotrexate, azathioprine, cyclophosphamide (particularly in granulomatosis with polyangiitis), and biologics such as rituximab or anti-TNF agents
• Manage jointly with a rheumatologist where there is systemic disease
• Hearing AIDS, and cochlear implantation for profound loss, which works well — but should be considered before the cochlea ossifies in an inflamed labyrinth
• The practical message — a rapidly progressive bilateral sensorineural loss deserves a trial of steroid, because the window for recovery is short and the alternative is permanent deafness in both ears
• The tempo makes the diagnosis — too fast for presbycusis, too slow for sudden deafness, and bilateral