Correlation among external auditory canal anomaly, temporal bone malformation, and hearing levels in patients with microtia.

We conducted a retrospective study to evaluate the relationship between external auditory canal (EAC) anomaly, temporal bone abnormality, and hearing levels using objective scoring systems in Chinese patients with microtia. The study population consisted of 106 ears of 94 Chinese patients (67 male and 27 female) aged 5 to 45 years (mean: 12.6) with microtia. The EAC abnormalities were classified into 4 types according to Schuknecht's criteria: type A, type B, type C, and type D. Developmental anomalies of the temporal bone were evaluated by Jahrsdoerfer computed tomography (CT) scoring system using high-resolution CT scans of the temporal bone. Temporal bone malformation parameters were divided into 4 subgroups: ossicular chain development, windows connected to the cochlea, aeration development of the middle ear, and facial nerve aberration. Hearing levels (air conduction and bone conduction) were examined. Outcomes parameters included correlation coefficients (r) and a number of other variables. The total points (10 points) and subtotal points related to ossicles (4 points), windows (2 points), aeration (2 points), and facial nerve (1 point) correlated inversely with the EAC abnormalities. The hearing levels (air conduction, r = 0.396, p <0.01; bone conduction, r = 0.21, p = 0.03) correlated significantly with the EAC abnormalities of Schuknecht's classification. We conclude that the better developed the external auditory canal, the better developed the temporal bone and the better developed the external auditory canal, the better hearing level. The hearing level also can serve as an indicator to determine whether a patient will be suitable for reconstructive surgery.