Yuko Suzuka

Meniere's disease and autoimmunity. Clinical study and survey

In order to clarify whether autoimmune mechanisms form part of the etiopathogenesis of Menieres disease, sera and endolymphatic sac tissues from 30 patients with Menieres disease were analyzed according to the clinical criteria for autoimmune diseases stated by Mackay & Burnet. Several cases showed hyper gamma-globulinemia, antibody elevation to Type II collagen in the serum and endolymph, positive staining to immunoglobulins and C3 or infiltration of immuno-competent cells in the endolymphatic sac, good response to prednisolone and combination with systemic immune disorders. Other examinations showed a significant elevation of OKT 4/8 ratio and a decrease of OKT8-positive cells, and elevated levels of circulating immune complex and antiviral antibody titers. It is suggested that certain cases of Menieres disease may have an altered immunological background, which may be attributed to an autoimmune mechanism dependent on humoral and/or cellular responses.

Alterations of charge barrier in the inner ear following immune reactions.

We investigated electron microscopically the changes of anionic sites of a charge barrier in the capillary basement membrane of the stria vascularis and endolymphatic sac following inner ear immune reactions. Hartley guinea pigs were immunized with bovine type II collagen, keyhole limpet hemocyanin, or horseradish peroxidase, with boosted and challenged antigens through the stylomastoid foramen. Animals were killed painlessly from several days up to 56 days after the antigen challenge. Polyethylenimine was used as a cationic tracer in order to observe the localization of anionic sites of the charge. In the animals immunized with bovine type II collagen or horseradish peroxidase, a significant decrease of anionic charge in the stria and the sac was found in the early stage of immunization. However, the keyhole limpet hemocyanin immunization group did not show any remarkable changes in the charge because of its lesser transfer into the inner ear due to of its high molecular weight and negative surface charge. A decrease of the charge under immunologic conditions may induce a hyperpermeability of vessels and a malabsorption of endolymph, and thus may cause endolymphatic hydrops.

Surgical Anatomy for Infralabyrinthine Approach to the Internal Auditory Canal

Surgical anatomy for infralabyrinthine approach to the internal auditory canal was evaluated using human temporal bone in order to understand advantages and disadvantages of this approach. The procedure is extracranial without any damage of labyrinth. Lateral exposure of the internal auditory canal allows for easy separation of the cochlear and vestibular nerves. There are some potential problems of little importance stemming from anatomical variations, such as high jugular bulb, forward positioned sigmoid sinus and poor pneumatization of the infralabyrinthine space. This approach offers access to the eighth cranial nerve with minimal risk and morbidity.