The treatment for AIED is high-dose oral or parenteral corticosteroids. Typically, treatment is initiated with oral prednisone at a dosing of 60 mg per day, as long as the patient does not have any contraindications to this therapy. A detailed list of possible side effects and complications of this therapy is given to the patient and includes hyperglycemia, insomnolence, hypertension, and mood disturbance, as well as sequelae of long-term usage such as moon facies, abdominal obesity, cataracts, and the low, but serious, risk of avascular necrosis of the femoral head. The high-dose steroid is continued for at least one month.
TABLE 3 Classification of AIED
1 Organ (ear) specific
Rapidly progressive bilateral sensorineural hearing loss All age ranges, although middle age most common No other clinical evidence of systemic autoimmune disease Positive otoblot (Western blot 68 kDa)
Negative serological studies (antinuclear antigen, sedimentation rate, rheumatoid factor, C1q binding assay, etc.) Greater than 50% response rate to high-dose steroids
2 Rapidly progressive bilateral sensorineural hearing loss with systemic autoimmune disease
Rapidly progressive bilateral sensorineural hearing loss
Hearing loss often worst with flare of autoimmune condition
Other autoimmune condition is present (systemic lupus erythematosus, ulcerative colitis, polyarteritis nodosa, vasculitis, rheumatoid arthritis, Sjogren's disease) Otoblot may be positive or negative
Serological studies will be positive in accordance with the illness (i.e., antinuclear antigen high titers, rheumatoid factor positive, circulating immune complexes) Steroid-responsive and may be managed with targeted therapies for underlying illness
3 Immune-mediated Meniere's disease
Bilateral, fluctuating sensorineural hearing loss with vestibular symptoms that may predominate
Subset of patients with delayed contralateral endolymphatic hydrops or recent instability of better hearing ear with burned out Meniere's disease Otoblot positive in 37-58%, may show presence of circulating immune complexes Steroid responsive, may require long-term immunosuppression due to relapses
4 Rapidly progressive bilateral sensorineural hearing loss with associated inflammatory disease (chronic otitis media, Lyme disease, otosyphilis, serum sicknessa) Evidence of profound drop in hearing with long-standing chronic otitis media May show inflammation of the tympanic membrane and perforations Hearing loss progresses despite treatment of the infectious agent (treponemal or rickettsial)
Otoblot negative, serological tests for the underlying disease may be positive and should be evaluated for granulomatous disease and vasculitis by biopsy if tissue is available
Steroid-responsive and may require long-term immunosuppression
5 Cogan's Syndrome
Sudden onset of interstitial keratitis and severe vestibuloauditory dysfunction Otoblot negative for 68 kDa, but postive for 55 kDa Responds to high-dose steroids although becomes resistant over long term
Young patients with idiopathic rapidly progressive bilateral sensorineural hearing loss leading to deafness Severe ear pain, pressure, and tinnitus Otoblot and all serology negative
May have an unrelated, non-specific inflammatory event that initiates ear disease Not responsive to immunosuppressive drugs although they are tried May be related in some instances to ototoxicity from narcotics aHas been reported after vaccinations although anecdotal. Abbreviation: AIED, autoimmune inner ear disease. Source: From Ref. 35.
Lower dosage or shorter-term therapy is fraught with exacerbations of AIED. If the patient has a good response, the steroid typically is slowly tapered. If an exacerbation occurs during the taper, full dose is resumed, with the hope of tapering at a later date. It is not uncommon for patients with AIED to require six or more months of high-dose steroids for adequate stabilization of their disease. If it appears that the hearing will be unstable with the tapering of prednisone, an adjuvant immunosuppressive is added to the regimen, as discussed below.
Plasmapheresis has also been advocated for refractory cases. Luetje studied 16 patients with AIED who underwent three sessions of plasmapheresis on alternate days. On long-term follow-up, roughly one-half of the patients required additional sessions of plasmapheresis, as they had initial benefit but relapsed later. Of the 16 patients, 8 had improved or stable hearing in one or both ears on long-term follow-up. Only four patients required immunosuppressive treatment on long-term follow-up (36,37). Further studies with this regimen have not been reported, however. Methotrexate showed initial promise for use in AIED, based on early case reports of efficacy, but a large, multi-institutional trial showed methotrexate to be no better than placebo (8). Etanercept (Enbrel), a TNF-a blocker, was effective in limiting hearing loss in AIED animal models, but unfortunately, studies have shown it to be no better than placebo in treating the disorder (11), although these results may have been dose dependant. Other TNF-a -blocking agents such as Remicade (infliximab) and Humira (adalimumab), as well as Rituxan (rituximab), a p-cell antagonist, are undergoing active clinical assessment for use in AIED.
Cyclophosphamide, a high-potency immunosuppressant, may be considered only for refractory cases with other serious rheumatological conditions such as polyarteritis nodosa or systemic lupus erythematosus in coexistence, but is contraindicated in children. Dosing is 1 to 2 mg orally per day, taken in the morning with copious fluids to minimize bladder toxicity. Side effects are substantial and include bone marrow and bladder toxicity with the risk of malignant transformation. Peripheral blood counts must be monitored closely for bone marrow suppression. Patients must be well informed of the risk of permanent sterility resulting from this medication.
Intratympanic therapy theoretically allows delivery of high levels of potent medications by diffusion through the round window membrane into the inner ear while obviating the systemic side effects. The pharmacokinetics of hydrocortisone, methylprednisolone, and dexamethasone was studied by Parnes, who documented that only limited amounts of corticosteroid were able to penetrate the blood-labyrinthine barrier and enter the inner ear with systemic administration in an animal model. Conversely, substantially increased levels of the corticosteroids were found within the perilymphatic as well as endolymphatic fluid upon intratympanic administration (38). Although intratympanic administration is promising, it is important to remember that much of the immune response within the inner ear is derived from recruited cells from the systemic circulation, which are not affected by intratympanic dosing. Currently, intratympanic steroid versus oral steroid treatment is being evaluated in a multi-institutional clinical trial for efficacy in sudden hearing loss.
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