Autoimmune inner ear disease--a real entity?

Involvement of autoimmune mechanisms in sudden-onset, rapidly progressive, bilateral inner ear disease is supported by the following evidence: (1) the inner ear contains immune cells and mediators (immunoglobulins); (2) animal models demonstrate inner ear damage after immunization with inner ear tissue; (3) experimental autoimmune inner ear disease appears to be transferable with sensitized T cells; (4) human SNHL can occur in the context of systemic immunologic disease; (5) SNHL can be improved by immunosuppressive therapy; and (6) patients with SNHL demonstrate elevated immune responses to inner ear proteins/tissue preparations. There are also several reasons, however, why the above inner ear disease cannot be termed "autoimmune": (1) in experimental models, inner ear damage may be produced during an in situ immune response to an irrelevant antigen; (2) histopathology is not yet extensive enough to confirm the role of immune cells and mediators in human disease; (3) immune reactivity to an organ-specific antigen associated with the inner ear has not yet been identified. At this time, therefore, clinical inner ear disease with evidence of immunologic involvement is termed "immune-mediated" rather than "autoimmune." IMIED is likely to represent a heterogeneous group of diseases with multifactorial causes but a common endpoint. Diagnosis is made primarily by clinical profile in association with laboratory testing to rule out neoplasia or infection. Investigational laboratory immunoassays for antibodies to inner ear proteins or hsp 70 appear to have promise for diagnosis or predicting clinical response to immunosuppressive treatment. Sensitivity and specificity of such assays have not yet been established.