[Otosclerosis. A paramyxovirus-induced inflammatory reaction].

Despite intensive investigation the cause of otosclerosis remains unknown. Recent immunohistochemical and electron microscopic studies of otosclerotic stapes have revealed a possible viral aetiology. Therefore we investigated the histology, ultrastructure and immunohistochemistry of fragments of otosclerotic footplates. Immunoglobulins G (IgG) and A (IgA) were found in plasma cells, oseocytes, chondrocytes and connective tissue of the active lesions. Polyclonal and monoclonal antibodies against paramyxovirus and rubella virus antigens produced reproducible reactions with these antigens at different sites of otosclerotic stapes, especially in the epithelial cells of the overlying middle ear mucosa. Using specific T-lymphocyte and B-lymphocyte markers about 80% of the lymphocytes present in the otosclerotic footplate proved to be T-lymphocytes. There was neither deposition of immunoglobulins nor any expression of viral antigens in non-otosclerotic footplates which were investigated as controls. Our results indicate that otosclerosis is an inflammatory reaction of the otic capsule initiated or caused by paramyxovirus and/or rubella virus. The silent progress of the disease and its onset under certain conditions, e.g. endocrine upsets, show similarity to slow viral infections.