Measurement of angle and length of the eustachian tube on computed tomography using the multiplanar reconstruction technique.

OBJECTIVE

To compare the anatomic features of the eustachian tube (ET) between children with and without otitis media with effusion (OME) and with adults.

METHODS

The angle and length of the ET in children with OME (54 ears, OME children) and without OME (50 ears, normal children), as well as those of normal adults (90 ears), were measured on computed tomography using the multiplanar reconstruction technique.

RESULTS

The angles of ET in the OME children group, the normal children group, and the normal adult group were 20.4 +/- 3.5 degrees and 21.2 +/- 4.8 degrees , 19.9 +/- 3.4 degrees and 20.0 +/- 3.6 degrees , and 27.3 +/- 2.7 degrees and 27.3 +/- 2.8 degrees on the right and the left sides, respectively. There was no significant difference between the right and the left side in any group (P = .541, P = .952, P = .978). The lengths of ET in the OME children group, the normal children group, and the normal adult group were 37.2 +/- 3.0 mm (mean +/- SD) and 37.6 +/- 3.2 mm, 37.5 +/- 3.3 mm and 38.0 +/- 3.2 mm, and 42.5 +/- 2.8 mm and 42.9 +/- 2.9 mm on the right and the left sides, respectively. There was no significant difference between the right and left sides in any group (P = .670, P = .597, and P = .545). Both the angles and lengths were significantly greater in the normal adult group than in either the OME children group or the normal children group (one-way analysis of variance and Fisher's protected least significant difference tests, P < .05), but there was no significant difference in either the angle or length of the ET between the OME and normal children groups (P > .05). In the OME and normal children groups, the angle was observed to constantly increase with age, and the values were found to be within the range of the adult size in all the patients older than 7.5 years and 7.7 years in the OME children group and the normal children group, respectively. As well as the angle, the lengths were observed to constantly increase with age, but the increase appeared to be greater at a younger age (until approximately 3 to 4 years) than at an older age, and the values were found to be within the range of the adult size in all the patients older than 6.8 years and 7.7 years in the OME children group and the normal children group, respectively.

CONCLUSION

The angle and length of the ET are more horizontal and shorter in infants than in adults. However, there is no statistical difference between the angle and length of the ET in infants with and without OME. These results lead us to believe that a short and horizontal ET may not be a main etiologic factor related to high susceptibility to OME in infants and children.