Immune-mediated inner ear disease

Immune-mediated inner ear disease (IMIED) is the preferred term for the syndrome involving cochlear dysfunction, leading to degrees of sensorineural hearing loss and vertigo. Although vasculitis has been inferred to be the cause of IMIED in some cases, histopathological proof of vascu-litis involving the inner ear in this condition is lacking. The condition does appear to be mediated in some fashion by the immune system; hence, the name IMIED. IMIED can occur in association with a recognized autoimmune condition such as Sjögren's syndrome, Wegener's granulomatosis, or giant cell arteritis, or as an isolated entity in which no other organ dysfunction is evident. The onset of hearing loss in IMIED is rapid compared with other entities that lead to auditory dysfunction. Hearing loss in IMIED occurs over the course of weeks to months. Patients with IMIED-associated hearing loss have problems with both hearing acuity and word discrimination. Following conversations in noisy environments (e.g., in crowded restaurants) may be particularly challenging. For patients with IMIED, vestibular problems that result from cochlear damage can be as challenging as the auditory dysfunction, if not more so. Up to 70% of patients diagnosed with IMIED demonstrate clinical improvement following glucocorticoid treatment. Prednisone (1 mg/kg/day) is a reasonable starting dose for the treatment of rapidly progressive sensorineural hearing loss secondary to IMIED. If the patient regains significant auditory and vestibular function within 2 weeks, tapering of the prednisone dose can begin in a taper designed to discontinue the medication over 2 months. For patients with severe or recurrent audiovestibular dysfunction secondary to IMIED, it is not clear whether long-term courses of high-dose glucocorticoids and additional immunosuppressive agents are effective in restoring inner ear function. Such treatment approaches should be used cautiously.