Epitympanic Area and Volume in Human Temporal Bones with and without Chronic Otitis Media

Abstract

Objectives: (1) Investigate the difference in epitympanic bony volume and size of tympanic isthmus (TI) between human temporal bones (HTBs) with and without chronic otitis media (COM). (2) Investigate the relationship between TI size and epitympanic bony volume in HTBs with and without COM. Methods: Eleven HTBs from children with COM (COM group) and 11 HTBs without COM (control group) were examined. Three-dimensional models were generated from HTB histopathologic slides with reconstruction software (Amira), and epitympanic bony volumes were measured. Within the boundaries of TI, only the aerated space, excluding exudates and soft tissues, were measured as aerated TI, and all space surrounded by the boundaries including exudates and soft tissues were measured as the bony TI. We chose the minimum aerated/bony TI area from all slides and compared them between the 2 groups. We also investigated the correlation between bony epitympanic volume and minimum aerated/ bony TI area in each group. Results: There were no significant differences in epitympanic bony volume or bony TI area between the groups. Aerated TI area in the COM group was significantly smaller than in control group ( P < .01). There was no relationship between aerated TI area and bony epitympanic volume in the 2 groups. In the COM group, there was a negative correlation between bony TI area and epitympanic volume ( P < .001). Conclusions: Our study suggests that congenital or developmental stenosis of the TI is not associated with epitympanic pathology, but blockage of TI with soft tissue pathology is.