Morphological Characteristics of Osseous External Auditory Canal and Its Relationship With External Auditory Canal Cholesteatoma in Patients With Congenital Aural Stenosis

Objective: To investigate the characteristics of stenotic external auditory canal (EAC) (e.g., shape, length, orientation, and curvature) and to compare them with those of the cholesteatoma and no cholesteatoma groups, which may help to explain cholesteatoma formation to a certain degree. Methods: Computed tomography scans of two groups of patients (with and without EAC cholesteatoma) were analyzed. We determined the degree of microtia, the stenosis of EAC, radius and curvature of osseous EAC bending (abbreviated as OEB-r and OEB-c, respectively), and other anatomic parameters of EAC by using Mimics and Matlab. Results: There was no significant difference in the degree of microtia between the cholesteatoma and no cholesteatoma groups using the Marx grading system. Additionally, no significant difference was found in the stenosis of EAC between the two groups. The OEB-r was smaller in the cholesteatoma group (4.62 ± 0.62 mm) than in the no cholesteatoma group (7.41 ± 0.50 mm), and the OEB-c was found to be larger in the cholesteatoma group (1.55 ± 0.05 × 10 mm−1) than in the no cholesteatoma group (1.10 ± 0.10 × 10 mm−1). Moreover, the OEB-c (OR, 8.60; 95% CI, 2.67–27.75) was associated with EAC cholesteatoma formation. Conclusion: The curvature of osseous EAC in the cholesteatoma group was significantly larger than that in the no cholesteatoma group. It is suggested that the curvature of osseous EAC was a risk factor for EAC cholesteatoma formation.

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