Autoimmune inner ear disease (AIED) was first reported by Lehnhardt in 1958 when he theorized that anticochlear antibodies were the cause of progressive bilateral hearing loss in 13 patients. In 1979, McCabe described 18 patients with progressive bilateral sensorineural hearing loss, who responded to immunosuppressive therapy. Since then, substantial research efforts and clinical investigations have greatly enhanced our understanding of this disorder; however, AIED remains a difficult disorder to investigate for several reasons. The delicate inner ear structures are not amenable to biopsy and are often destroyed even by accessing the inner ear compartment. Additionally, the inner ear is encased in some of the densest bone in the body. Finally, its inherent size makes imaging of its functional components extremely difficult. For these reasons, the true pathogenesis of this disorder remains obscure. Much of our current understanding is based on animal models of the disease, which have definitively demonstrated the immune response itself as a cause of inner ear injury.
AIED can exist either in isolation or in combination with other systemic autoimmune disorders. Although uncommon, it remains one of the few reversible causes of sensorineural hearing loss. Timely administration of appropriate medication can stabilize or improve hearing as well as vestibulopathy in the majority of cases. Although active investigation into new agents is under way, high-dose corticosteroid therapy remains the treatment of choice for the disorder. Great progress has been made in our understanding of AIED, but much work is needed before its true nature is understood. This chapter will review the basic immunology of the inner ear, the pathogenesis of AIED based on animal models, the clinical manifestations and diagnostic features of the disorder, and its treatment.