A Histopathologic Comparison of Eustachian Tube Anatomy in Pediatric and Adult Temporal Bones

In children, the distance between the carotid canal (CC) and Eustachian tube (ET) is not significantly narrower than the adult population.

ET dysfunction treated with ET dilation is FDA approved for adults. Several studies describe the close relationship between the CC and the ET in adults, but the anatomy of the ET has not been well defined in children. This study seeks to investigate these relationships in the pediatric population.

Histologic sections from 23 temporal bones of pediatric patients ages 0 to 18 were reviewed by two independent observers. The distance between the CC and the cartilaginous Eustachian tube (CET), bony-cartilaginous junction (BCJ), and bony Eustachian tube (BET) were measured. Fifteen adult temporal bones were used as a control group.

The distance to the CC was narrowest at the BET, and was actually higher in the pediatric population when compared to adults (0.5 mm and 0.2 mm, respectively, p = 0.06). The CC-CET distance was smaller in the pediatric group (2.3 mm vs 3.3 mm, p < 0.01). The bony-cartilaginous junction is often the region of most concern during dilation. There was no significant difference between the CC-BET distance in pediatric and adult groups (1.9 vs 2.3 mm, p = 0.20).

CET-CC is smaller in the pediatric population, as expected due to smaller anatomic structures. However, the variable incline of the ET results in a CC-BCJ distance that is similar to the adult population. Although imaging studies are necessary.