Facial canal dehiscence, dural exposure, and labyrinthine fistula in middle ear cholesteatoma and mastoiditis.

PURPOSE: To analyze the prevalence and associations of facial canal dehiscence (FCD), dural exposure, and labyrinthine fistula in chronic otitis media (COM) with and without cholesteatoma. METHODS: This was a retrospective study performed in an academic medical center. Patients who received tympanoplasty with mastoidectomy for COM with and without cholesteatoma were included. The prevalence of FCD, dural exposure, and labyrinthine fistula in COM with and without cholesteatoma (mastoiditis) and their relationships were analyzed. RESULTS: A total of 189 patients, including 107 (56.6%) females and 82 (43.4%) males, with 191 ears were included. There were 149 cases (78.0%) of cholesteatoma and 42 patients (22.0%) with mastoiditis. FCD was noted in 27.5% of patients with cholesteatoma and 9.5% of patients with mastoiditis. Dural exposure was found in 21 patients (14.1%) with cholesteatoma and 4 patients (9.5%) with mastoiditis. Eleven patients (7.4%) with cholesteatoma and 1 patient (2.4%) with mastoiditis had labyrinthine fistula. Patients with a labyrinthine fistula had nearly a fivefold greater chance (OR = 4.924, 95% CI = 1.355-17.896, p = 0.015) of having FCD than those without a fistula. There was a positive correlation between dural exposure and labyrinthine fistula (P = 0.011, Fisher's exact test). CONCLUSION: FCD, dural exposure, and labyrinthine fistula are common complications in COM. These complications are more frequently observed in patients with cholesteatoma than in patients with mastoiditis. Surgeons should pay more attention to the treatment of COM.

Imaging analysis of dural exposure in cholesteatomas with a skull base defect.

PURPOSE: Dural exposure during cholesteatoma surgery can pose a risk of cerebrospinal fluid leakage or residual disease. Therefore, delicate handling of the area surrounding the bone defect in the cranial fossa is required. However, in small-sized defects, preoperative prediction of dural exposure can be challenging. This study aimed to evaluate the diagnostic value of computed tomography (CT) for preoperative prediction of cholesteatoma-related dural exposure in bone discontinuities in the skull base. METHODS: We evaluated serial high-resolution CT images showing bone density discontinuities in the middle cranial fossa (MCF) requiring mastoidectomy for cholesteatoma. The CT and intraoperative findings were analyzed retrospectively. We evaluated the length between the superior margins of the bone density discontinuities using coronal CT planes. Receiver operating characteristic (ROC) curves were constructed to determine the optimal cut-off values. RESULTS: We extracted data from 107 bone density discontinuities, among which 54 (50.5%) showed dural exposure intraoperatively. Discontinuities with dural exposure (n = 54) had significantly greater lengths than did those without (n = 53) (p < 0.001, Wilcoxon rank-sum test). The area under the curve was 0.9780 according to the ROC analysis, and the optimal cut-off value was determined to be 2.99 mm (sensitivity 92.59%; specificity 94.34%). CONCLUSION: A bone density discontinuity length of > 2.99 mm in the MCF on coronal CT plane is a reliable diagnostic marker for cholesteatoma-related dural exposure. Thus, preoperative high-resolution CT analysis can inform optimal surgical preparation and planning before manipulating the area surrounding the osteolytic lesion in the MCF.