Identifying the etiopathogenesis of MtniBre’s disease (MD) has been the object of several studies since Prosper MCnikre first described the main symptoms of this disease in 1861 : fluctuating hearing loss, vertigo, and tinnitus. Endolymphatic hydrops is considered the main pathological finding associated with MD and a good deal of research has been directed toward the identification and understanding of its underlying mechanisms. Because the sensory neural elements of the inner ear cannot be visualized in their diseased state in vivo, diagnosis of MD has been based mainly on the evaluation of the clinical symptoms and results of audiological tests. Since Rask-Andersen and Stahle’ first recognized the inner ear as having an immunological function, several authors have added their support to the idea of a multifactorial origin by hypothesizing a possible role of the immunological system in MD pathogenesis. In fact, in 1983 Shea described the possible role of autoimmune mechanisms in patients with typical MD who responded favorably to steroid treatment or plasmapheresis.* Immunohistochemical studies also revealed the presence of an immunological reaction within the inner-ear tissues, such as stria vascularis, supporting connective tissues and blood vessels, in only a small number of patients inve~tigated.~-~ Although these studies are certainly affected by technical problems mainly linked to tissue preservation and processing, they are still suggestive of the idea that certain types of MD are caused by immunological factors of the inner ear. Immune inner-ear disease is a comparatively new area of clinical research, and over time different immunological reactions have been recognized and this has led to the introduction of several laboratory tests in the clinical evaluation of these patients. The pathogenetic mechanisms underlying inner-ear disorders seem to be mainly due to either type 2 cytotoxic interaction of autoantibodies with tissue-bond antigen or a type-3 IgGand IgM-mediated reaction that creates circulating immune complexes. The generic mechanism inducing tissue damage is a specific T-cell clonal expansion, specific autoantibody formation, complement cascade activation with inflammatory cell recruitment. Inner-ear damage and the resultant symptoms could depend upon the type of antigen and tissues as well as the anatomical site involved in the inflammatory reaction, which could be critical in determining endolymphatic hydrops. One of the main issues is the factor that triggers a Tand B-lymphocytes reaction and the production of autoantibodies against inner-ear structure in patients with