High-resolution computed tomographic features of the stapedius muscle and facial nerve in chronic otitis media.

ABSTRACT

OBJECTIVE: To improve preoperative recognition of the morphologic features of stapedius muscle and facial nerve in cases of chronic otitis media by providing a systemized description using temporal bone high-resolution computed tomography (HRCT). STUDY DESIGN: Retrospective review of HRCT scans from 212 patients. SETTING: Tertiary hospital affiliated to Fudan University. PATIENTS Men and women undergoing surgery for chronic otitis media. No preference for demographics or side presenting otitis media. INTERVENTION Therapeutic surgery. MAIN OUTCOME MEASURE: Location and morphology of stapedius muscle and facial nerve. RESULTS: The stapedius muscle was encountered in 90.5% of axial (n = 181) and 87% of coronal sections (n = 174), and differences between sides and genders were not significant (p > 0.05). Five categories of anomalies or pathologic features were identified in axial layers, and 3 categories were identified in coronal layers. Two axial and 2 coronal CT planes were found to be especially significant in imaging the facial nerve and its morphology (p < 0.001), whereas axial planes were more apt to show stapedius muscle features. Other pathologic features were also observed significantly more from specific CT imaging planes. CONCLUSION: The presence the stapedius muscle and the morphology between the stapedius muscle and the facial nerve vary between different observation areas, and some CT planes provide more useful information than others. The imaging planes outlined in this study can be used to systematically and correctly identify certain facial nerve and stapedius muscle features and clarify unfamiliar pathologic anatomy in preoperative planning.