DEVELOPMENT OF TYMPANOSCLEROSIS - CAN PREDICTING FACTORS BE IDENTIFIED

Hypothesis: The etiological hypothesis is that there might be factors triggering an immunological chain reaction that eventually leads to ty mpanosclerosis formation. Background: Tympanosclerosis is a condition leading to a calcification process in the middle ear and, occasionally , also to the lining of the inner ear. This sometimes leads to hearing loss due to fixation of the middle ear ossicles. In severe cases, dea fness may occur as a result of the inner ear impairment. Surgery is th e treatment offered, often with poor long-term results, and, alternati vely, prescription of hearing aids. Some patients develop tympanoscler osis after mild inflammatory otitis media processes whereas some heal without tympanosclerosis after more aggressive infections. This differ ence may be due to individual variations in the inflammatory response, The biological mechanism of calcification in tympanosclerosis is prob ably similar to that occurring in other calcifying tissues due to dise ases. Methods: The present investigation was performed to develop meth ods for immunohistochemical analyses of this delicate tissue consistin g of both hard bone and the very thin tympanic membrane. Sprague-Dawle y rats were inoculated with a suspension of Streptococcus pneumoniae, type 3, into the middle ear and sacrificed after 1 week up ro 6 months , A new technique was elaborated where the whole specimen was prefixed briefly and then en bloc incubated with the primary antibodies and af ter that decalcified in edetic acid (EDTA). Primary antibodies against macrophages were used for the immunohistochemical staining. Results: Acute otitis media was successfully induced in the rats and myringoscl erosis tvas seen in 30% of the animals, often localized close to the b ony frame where macrophages could also be detected. Conclusions: Acute otitis media and myringosclerosis were introduced In the animals. Con ventional immunological techniques were tested on this delicate tissue . A new method for immunohistochemical staining was elaborated in whic h specimens were stained en bloc before decalcification and sectioning were performed. Expression of macrophages was demonstrated in the tym panic membrane.