Effects of Otitis Media on the Eustachian Tube: An Animal Experiment

Abstract

Objective: To study the effect of the acute otitis media (AOM) on the middle ear mucosa and auditory tube in rabbits and to evaluate the results histologically. Material Methods:The study was carried out on 35 adult rabbits (New Zealand white rabbits), weighing 1500-1800 grams. The middle ear was inoculated with a bacterial suspension containing S. aureus to induce acute otitis media. Based on the exposure time of 1, 2, 4, 12, 24 weeks, the animals were classified into five groups. The rabbits in the acute otitis media group were killed after they were exposed for 1 and 2 weeks (acute), four weeks (subacute), or 12 and 24 weeks (chronic), and they were compared with the control group. The left control middle ear, the right inoculated bulla and the eustachian tube were removed. Sections of the temporal bones were dissected on block by covering the middle ear cavity and nasopharynx passing through the eustachian tube. Results:The goblet cells in the group AOM after one week was as dense as those in the control group. There was no difference between the groups in subepithelial edema, the number of eosinophils, subepithelial vasodilatation, intraepithelial gland formation and, subepithelial gland formation (p>0.05). The gland volume and the goblet cells density were extended to peak two weeks after the inoculation since there was primarily a volume increase in the components of the mucous gland. There was a significant increase in the volume of the gland layer within at least 12 weeks after the inoculation of the bacterial middle ear, primarily since there was an increase in a volume of the components of the mucous gland. Although there was a decrease in the volume 12 weeks after acute infection, it was completely normalized after 24 weeks. Conclusion:Acute otitis media directly affects the auditory tube. Besides, excessive mucus secretion and goblet cell proliferation included histologic changes of auditory tube mucosa