In 1981, the authors described a type II collagen-induced autoimmune ear disease (CIAED) model. The purpose of this study was to gather further evidence that this is a sound animal model to use in evaluating inner ear diseases. The temporal bone lesions of CIAED in Lewis and Wistar rats were characterized by the presence of sensorineural hearing loss with mild atrophy of the organ of Corti and spiral ganglion degeneration, vestibular dysfunction with vacuolar degeneration of the crista ampullaris, otospongiosis-like lesions in the tympanic annules, cochlear vasculitis, and eustachian tube disease. Both cellular and humoral immune responses to type II collagen were demonstrated. The induction of ear lesions depends on many factors. In general, animals immunized with antigens in complete Freund's adjuvant showed relatively more severe lesions than animals immunized with antigens in incomplete Freund's adjuvant, but the duration of the immunization seems to be a more important factor in reproducing severe lesions. The strain and the source of the animals are also important factors in autoimmune inner ear diseases, as is the condition of the host animals. Subclinical or clinical mycoplasma infection in the rat markedly reduced the incidence and severity of lesions in type II collagen-induced arthritis. Many researchers did not consider sialoductal adenovirus, widely present among laboratory rats, a lesion-producing factor in rats. Although many factors influence the induction and severity of CIAED, these animal models provide an excellent new avenue of inner ear research.

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Studies of cochlear blood flow in guinea pigs with endolymphatic hydrops.

Laser Doppler flowmetry was used to assess cochlear blood flow (CoBF) in guinea pigs with experimental endolymphatic hydrops following intravenous infusion of 5 types of drugs: 50% glycerol, 70% isosorbide, 20% mannitol, 7% sodium bicarbonate, and 1% diphenidol. The magnitude of the CoBF changes following infusion tended to be smaller in the hydropic ears than in the normal control ears. A significant reduction in CoBF changes was observed in hydropic ears infused with isosorbide and sodium bicarbonate. These results suggest that the cochlear microvascular sensitivity to various stimuli such as drug infusion is reduced in hydropic ears. This may result from atrophy of the stria vascularis which is often observed in the hydropic ears of guinea pigs. Thus it seems likely that the same reaction occurs in the inner ear of patients with Ménière's disease in whom atrophy of the stria vascularis is also presumed to exist in conjunction with extensive endolymphatic hydrops. Therefore, it seems probable that the function of the microvasculature of the stria vascularis is impaired in the inner ear of patients with Ménière's disease, resulting in the slow progressive deterioration of the inner ear with time.

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Intraoperative mitomycin C in endolymphatic sac surgery for Ménière's disease: A pilot study.

The long-term results of endolymphatic sac (ES) shunt surgery in Ménière's disease have been reported to be unsatisfactory compared to the short-term results, probably because of fibrosis and/or reclosure of the incised ES. To solve this problem, we tried to apply mitomycin C (MMC) intraoperatively to the incised ES as used in trabeculectomy for glaucoma. MMC has an antiproliferative effect as well as an antineoplastic effect. Thus, it is expected that MMC would have a benefit to prevent rapid fibrosis and/or reclosure of the ES. MMC did not show any ototoxicity in our animal study and we started a clinical trial after being approved by the Ethics Committee for Human Research at our university. Fourteen patients with Ménière's disease underwent ES mastoid shunt surgery with intraoperative application of MMC and they were followed up more than 6 months. No patients experienced vertigo, although some complained of slight dizziness. Five patients out of 14 showed remarkable hearing improvement by more than 10 dB, accompanied with decrease of tinnitus.

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Antibodies against inner-ear proteins in the sera of patients with inner-ear diseases.

Sera from patients with various inner-ear diseases, especially Ménière's disease, were investigated by Western blot against guinea pig inner-ear proteins. Of 45 patients, 24 (53%) with various inner-ear diseases had antibodies against inner-ear proteins, compared with 0 of 10 (0%) in control subjects without inner-ear diseases. Of the 10 proteins that showed a positive reaction with patient sera, the 28-kD band was unique in that it appeared only in the membranous fraction of the inner ear and was highly positive (28%) in reaction with Ménière's disease patient sera. The results in the present study with proteins extracted from guinea pig inner ear were consistent with our previous study using proteins from human inner ear, suggesting that the 28-kD protein may be a candidate for detecting autoimmune inner-ear disease.

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Comparison of effectiveness of maneuvers and medication in the treatment of benign paroxysmal positional vertigo.

In this paper, the treatment by medication together with two maneuvers-the particle repositioning maneuver (PRM) reported by Parnes and Price-Jones and the liberatory maneuver (LM) reported by Semont et al.-were compared with treatment by medication alone. Fourteen of 15 cases (93.3%) treated with the PRM and 11 of 14 cases (78.6%) treated with the LM showed improvement after 2 weeks. These results were better than that obtained by medication alone, in which 8 of 26 cases (30.8%) showed improvement after 2 weeks. The most important benefit of these maneuvers seemed to be the speedier recovery than with medication alone, as there was no significant difference in the late success rate after 3 months between the maneuvers and medication alone.

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PubMedDate not supplied

Antibody activity in perilymph from rats with type II collagen-induced autoimmune inner ear disease.

Rats were immunized with native type II bovine collagen to induce autoimmune inner ear disease, and the antibody activity in the inner ear fluid was measured. Antibody activity against type II collagen was detected in the perilymph at about 10% to 20% of serum level. Thus, the presence of antibody against type II collagen in inner ear fluid may imply an immune injury mechanism in inner ear diseases.

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PubMedDate not supplied

Experimental study on Meniere's disease.

Experimental hydrops caused by underabsorption of endolymphatic fluid is a model of remissional stage of Meniere's disease. In this study, another type of model, ie, hydrops caused by overproduction of endolymphatic fluid, was accomplished by applying various pressures into scala media through a micropipette via stria vascularis. This type of hydrops could be a model of attacks of Meniere's disease. By using two types of the model, effects of glycerol administration and of opening the endolymphatic sac were discussed.

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PubMedDate not supplied

Histopathologic findings in surgical specimens of endolymphatic sac in Meniere's disease.

Two types of abnormality in the endolymphatic sac acquired at shunt surgery are presented. One was deep brown pigmentation in the subepithelial connective tissue. The pigment did not react to Prussian blue, thus ruling out hemosiderin. The other, in seven out of eight specimens, was the perisaccular fibrosis. The fibrotic foci in four cases were assumed, from the findings under ordinary illumination and polarized light microscopy, to be reorganized scar tissue.

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