Analysis of unilateral sclerotic temporal bone : how does the sclerosis change the mastoid pneumatization morphologically in the temporal bone?

Backgrounds Some disorders, such as otitis media and Eustachian tube dysfunction, may cause the temporal bone to become sclerotic. A sclerotic temporal bone has the tendency to shrink. The aim of this study was to evaluate the morphologic changes that result from sclerosis of the temporal bone. Methods We measured 9 variables on 2 axial images, and 8 variables on 2 coronal images in healthy ears and diseased ears in 37 patients with unilateral chronic otitis media. We also measured the volume of mastoid pneumatization. Results The distance from sigmoid sinus to Henle's spine was correlated to the degree of volume reduction, and it accounted for about 17.7% of the total variation in volume reduction. There was no difference in the sigmoid sinus type in comparisons between sclerotic and pneumatic mastoids. Conclusions The sclerosis of the temporal bone was observed to reduce the volume of the mastoid pneumatization. However, a large portion of the volume reduction may result from the sclerotic change in the air cell system, rather than from shrinkage of the mastoid bone. Therefore, the location of surgically-important structures, in the middle and inner ear, is only rarely changed in sclerotic temporal bone.