The Association of External and Middle Ear Anomaly and Mandibular Morphology in Congenital Microtia.

OBJECTIVE

To investigate the relationship between the severity of ear anomaly and mandibular dysplasia in congenital microtia.

STUDY

DESIGN

Retrospective case review.

SETTING

Sapporo Medical University Hospital.

PATIENTS: Congenital microtia: 44 patients over a period of 4 years.

INTERVENTIONS: The height of the condylar process of the mandible was assessed by three-dimensional computed tomography (CT), and the patients were divided into three groups based on the ratio of the condylar process height on the affected side to that on the unaffected side: Group A, ≥1.00; Group B, 0.99 to 0.85; Group C, <0.85. Developmental abnormalities of the ear were evaluated using Jahrsdoerfer's scoring system on high-resolution CT scans.

MAIN OUTCOME MEASURES: Nonparametric statistical tests were used to determine correlations between the height of the condylar process of the mandible and Jahrsdoerfer's score.

RESULTS

The total Jahrsdoerfer's score for each group was 7.36 ± 2.23, 7.28 ± 0.10, and 4.52 ± 0.30, respectively; this value was significantly lower in Group C than in the other groups. In terms of subtotal points, oval window open, middle ear aeration, and mastoid pneumatization correlated significantly with mandibular dysplasia. Patients in Group C tended to have grade III microtia, by Marx's classification. Facial nerve weakness was not significantly correlated with mandibular dysplasia.

CONCLUSIONS

In congenital microtia, mandibular development correlated significantly with aeration of the middle ear space, pneumatization of the mastoid, and formation of the oval window, but not with the presence of a bony part of the external auditory canal or with ossicular development.