Otitis media with effusion is a disease associated with the various forms of effusion in the middle ear cavity and hearing impairment. Negative pressure state in the middle ear cavity due to dysfunction of Eustachian tube results in the formation of effusion from plasma, interstitial fluid or the secretory cells in the mucosa due to various histopathological changes of mucosa.
It is thought that the mucosal changes well explain the pathogenesis and pathology of otitis media with effusion and the observation of the mucosal changes at the various locations of the middle ear cavity would be helpful to understand the pathogenesis of otitis media with effusion.
The author had induced otitis media with effusion experimentally in rabbits by the tubal occlusion, and had observed the histopathological changes at the six location of middle ear mucosa, such as inferolateral and inferomedial surface of hypotympanic bulla, transitional zone of hypotympanic bulla, promontory, tympanic membrane, epitympanum, during the course of time after experiment and reached the following results.
1. In histopathological changes, epithelial hyperplasia of the middle ear mucosa, capillary proliferation and inflammatory degree were most marked at the transitional zone of the hypotympanum and the least marked at the mucosa of the tympanic membrane.
2. Fibrosis of the submucosal connective tissue layer was most marked in the transitional zone and promontory.
3. The mucosal changes at each location were most prominent at the 14th day, then 28th day of tubal occlusion and decreased gradually.
4. The character, cellular component and bacteria in effusion of the middle ear cavity somewhat reflect the degree of mucosal damage generally, but there seems to be no specific relationship with different site of mucosa.
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