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

To determine the prevalence of cochlear-facial dehiscence (CFD) and to examine the influence of otic capsule area, age, sex, and race on CFD. Descriptive study of archived temporal bone specimens. 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. 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 (β = -0.001) (p < 0.005). Thicker CFPW was associated with males (β = 0.024) and non-Caucasian individuals (β = 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). 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.