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.