Autoimmune inner ear disease

The role of the immune system in mediating inner ear pathology has received considerable attention over the past two decades. The purpose of this paper is to summarize recent basic science research into the pathogenesis of autoimmune inner ear disease (AIED), review the current diagnostic work-up for patients with suspected AIED, and delineate treatment strategies.

Basic science and clinical studies have been performed to delineate the mechanisms by which autoimmune processes may affect the ear and to develop treatment strategies to reverse this pathology. AIED refers to a rapidly progressive (over a course of weeks to months) sensorineural hearing loss that responds to the administration of corticosteroids. In addition, systemic autoimmune diseases (eg, vasculitides, lupus, Wegener granulomatosis) can secondarily affect the inner ear. Although a number of diagnostic tests for AIED have been advocated, the diagnosis of this entity is still predicated on a positive therapeutic response to corticosteroid administration. Alternate immunosuppressive regimens, designed to be used in patients who cannot be weaned off corticosteroids or whose disease becomes refractory to treatment, have proven to be difficult to develop. Methotrexate, which initially showed promise, has recently been shown to be ineffective in preventing progression of hearing loss. Further research is required to better delineate the pathophysiologic mechanisms involved in AIED and to establish more effective and better tolerated treatment regimens.

The original enthusiasm that was generated by the concept that immune-mediated mechanisms may mediate reversible forms of inner ear pathology has been tempered by the realities conveyed by scientific research. The pathophysiology of AIED is still not well understood. Multiple potential mechanisms have been identified that can result in immune-mediated inner ear pathology. The diagnosis of AIED is based on clinical presentation and response to the administration of corticosteroids. Diagnostic testing may support the diagnosis, and the results of a recent multicenter study should clarify the role of immunologic testing in the diagnosis of this entity. Treatment options are limited, with corticosteroids being the only validated treatment option, and methotrexate offering no significant benefit to patients. The role of cyclophosphamide is restricted to patients willing to endure the attendant risks. With the advent of cochlear implants, the administration of toxic medications to preserve hearing at all costs is a less desirable option.