Association Of Eustachian Tube Anatomy And Mastoid Pneumatization With Cholesteatoma Extension In Unsafe-Type Chronic Suppurative Otitis Media On Temporal Bone HRCT

Abstract

Background: Unsafe-type chronic suppurative otitis media (CSOM) with cholesteatoma is a destructive middle ear disease that can give rise to serious complications. The anatomical relationship between the Eustachian tube (ET) and mastoid pneumatization with the degree of cholesteatoma extension remains inconsistent. High-Resolution Computed Tomography (HRCT) of the temporal bone enables evaluation of ET anatomy and assessment of cholesteatoma extension using the STAM score. Objective: To analyze the association of ET anatomical parameters and degree of mastoid pneumatization with cholesteatoma extension in patients with unsafe-type CSOM based on temporal bone HRCT. Methods: A retrospective cross-sectional analytical observational study was conducted on 59 patients (61 ears) with unsafe-type CSOM and cholesteatoma confirmed intraoperatively at Dr. Soetomo General Hospital Surabaya during the 2023 to 2025 period. Parameters assessed included ET length, pretympanic diameter, ET angle relative to Reid’s plane, degree of mastoid pneumatization, and STAM score (0 to 4). Analysis was conducted using correlation tests, group comparisons, K-Means clustering, diagnostic analysis, and interobserver reliability testing. Results: The mean ET length was 38.21 ± 3.89 mm, pretympanic diameter 2.93 ± 0.89 mm, and ET angle 29.18 ± 4.27°. Most subjects had pneumatic mastoid (55.7%) and a STAM score of 4 (90.2%). No significant association was found between ET length (p=0.087), pretympanic diameter (p=0.486), ET angle (p=0.304), or mastoid pneumatization (p=0.110) with STAM score. Temporal bone HRCT also showed excellent measurement reliability (ICC 0.954-0.997). Conclusion: Eustachian tube anatomical parameters and mastoid pneumatization were not associated with the degree of cholesteatoma extension in unsafe-type CSOM. ET anatomy likely plays a greater role as a predisposing factor for cholesteatoma formation than as a determinant of the extent of its spread. Temporal bone HRCT remains a reliable diagnostic modality with an excellent reliability.