Cranial anatomy and otitis media: a cadaver study

The eustachian tube is regarded as an etiologic factor for otitis media. Although anatomic cranial differences also are suggested as a factor, few scientifically rigorous studies of these differences have been reported.

Thirty-five adult cadaveric crania were examined.

Multiple (32) linear and angular cranial measurements were performed. For evidence of prior otitis media, there were two indicators: small mastoid pneumatization seen radiographically and abnormal tympanic membranes at photographic tympanoscopy. Each measurement and each categorization were done twice, independently. The average of the two measurements was used for each comparison. Only consistent categorizations were used for comparison.

Relatively short eustachian tubes were found to associate with both indicators of childhood otitis: r=0.39, p < 0.05. A relatively short distance from midsella turcica to staphylion, and short distance between the ears, also were associated with otitis. No angular relation of either the bony or cartilaginous eustachian tube correlated with the otitis indicators. Bilateral symmetry of pneumatization and tympanoscopic categorization, and of the various linear and angular measurements, was apparent.

The association of otitis media with some cranial base anatomic differences is endorsed. Comparatively long eustachian tubes, long distance from midsella to staphylion, and large interear length correlate with indicators of healthy middle ears.