New morphometric findings in adhesive otitis media: Petroclival angle and eustachian tube-tympanic cavity ventilation angle

Abstract

Objective Observations during adhesive otitis media (OM) surgery led us to consider that morphometric variations might cause formation of the middle ear cavity with smaller bony boundaries during developmental process. Among the various factors mentioned in the literature, we thought that angle of the petrous bone relative to the midsagittal line and the eustachian tube-tympanic cavity ventilation angle might be factors in the course of adhesive otitis media. Methods Axial computerized tomography scans from 14 patients with adhesive OM and 19 cases (control group) with normal middle ear-tympanic membrane were retrospectively examined in terms of petroclival angle and eustachian tube-tympanic cavity ventilation angle. Measurements of these two angles were compared between the two groups. A correlation was also investigated between these two angles. Results The petroclival angle (54.5° vs 62.3°) and the eustachian tube-tympanic cavity ventilation angle (156° vs 162.6°) in the adhesive OM group were narrower than those of controls ( p < 0.01). The correlation analysis showed that there was a strong association between two angles ( r, 0.803; p < 0.01). Conclusions More medially positioning of the petrous bone and acutely angled-eustachian tube-tympanic cavity ventilation axis were observed in this study. It would be reasonable to conclude that these findings might take part in development of adhesive OM. We should also admit that these results do not decline the previous theories that account for development of the adhesive otitis media.