Prevalence of Cochlear-Facial Dehiscence in a Study of 1,020 Temporal Bone Specimens.

OBJECTIVE: To determine the prevalence of cochlear-facial dehiscence (CFD) and to examine the influence of otic capsule area, age, sex, and race on CFD. STUDY DESIGN: Descriptive study of archived temporal bone specimens. MATERIALS AND METHODS: Targeted sections from 1,020 temporal bone specimens were scanned and examined for CFD. Cochlear-facial partition width (CFPW) and otic capsule area (OCA), a marker of bone thickness, were measured using image analysis software. Demographic data were analyzed using multiple linear regression analysis. RESULTS: The mean CFPW was 0.23 mm (range, 0-0.92 mm; SD, 0.15 mm). Six patients were completely dehiscent (0.59%). Fallopian canal width, age, sex, race, and OCA were found to be significant predictors of CFPW. Age was found to be negatively correlated with CFPW (beta = -0.001) (p < 0.005). Thicker CFPW was associated with males (beta = 0.024) and non-Caucasian individuals (beta = 0.031). The mean OCA for dehiscent specimens (mean, 9.48 mm; range, 6.65-11.58 mm; SD 3.21 mm) was significantly smaller than the mean OCA for nondehiscent specimens, (mean, 12.88 mm; range, 6.63-21.92 mm; SD, 2.47 mm) (p < 0.01). CONCLUSION: CFD occurred in nearly 0.6% of specimens in this temporal bone collection. Close to 35% of patients were sufficiently thin (<0.1 mm) to appear dehiscent on computed tomography scanning. Smaller OCA correlated with thinner CFPW, suggesting a developmental factor. Older, female, and Caucasian patients may have a greater risk for CFD and its associated symptoms.