: Hypothesis: There may be findings peculiar to the temporal bones of children with Down's syndrome (DS). The purpose of this study is to investigate the temporal bone histopathology of the children with DS.
Background: Otitis media with effusion is a highly prevalent condition with DS. Knowledge of the volume of the tympanic compartments and the area of the tympanic isthmus might be important to find out the pathogenesis of highly prevalent otitis media with effusion in those patients.
Methods: We compared the volume of the epitympanum, mesotympanum, and the areas of the tympanic isthmus and tympanic orifice of eustachian tube in temporal bones from patients with DS. We also investigated the eustachian tube histopathologically.
Results: The mean volume of the epitympanum and the mesotympanum was significantly smaller in the DS group than the control group. We found no significant difference in the mean diameter of the protympanic opening and tympanic orifice between the two groups. The mean narrowest area of the aerated and bony tympanic isthmus also was not significantly different between the two groups. An immature development of eustachian tube and cartilage was seen. We found mesenchyme remaining at the epitympanum and/or mesotympanum in all specimens in the DS group, and in five specimens in the control group.
Conclusion: In the presence of the small middle ear, poorly developed eustachian tube, and tensor muscle, a vicious circle occurs, making otitis media with effusion difficult to resolve.