Difference in facial canal anatomy in terms of severity of microtia and deformity of middle ear in patients with microtia.

Abstract

To study the difference in the facial canal anatomy in terms of the severity of microtia and deformity of the middle ear in patients with microtia using high-resolution computed tomography (HRCT). Forty-six ears with microtia were examined by HRCT. These ears were graded based on two systems of classification and scoring, respectively. The HRCT findings of each group were compared with those of other groups by multiple comparison using the Tukey honestly significant difference test. Forty-six ears with microtia (unilateral microtia, n = 12; bilateral microtia, n = 34) were examined by HRCT. These ears were graded based on two systems of classification and scoring, respectively. The HRCT findings and age distribution of each group were compared with those of other groups by multiple comparison using the Tukey honestly significant difference test. The mastoid portion of the facial nerve was 3 mm more anteriorly displaced in patients with grades II and III microtia than in those with grade I microtia (P <.01). From the scoring system that was used, the course of the facial nerve was not significantly different between patients with a score of 5 points or less and those with a score of 6 points or more. The mastoid portion of the facial nerve in patients with grades II and III microtia would be more anteriorly displaced because of hypoplasia of the second genu.