Objectives: To determine the relationship, if any, between body mass index (BMI) and attenuation of the arcuate eminence (AE).
Study design: Case series with chart review.
Setting: Tertiary neurotologic referral center.
Subjects and methods: Submillimeter distances were recorded from high-resolution temporal bone computed tomography (CT) scans of 50 patients (100 sides). The AE (defined as the superiormost location of the petrous bone over the otic capsule), the bony apex of the superior semicircular canal (SSC), and the geniculate ganglion (GG) were identified and 3-dimensional distances measured. The height of the AE relative to the bony apex of the superior semicircular canal was determined using Euclidean geometry using the fixed anatomical landmark of the GG as the origin. Correlations between AE and BMI were calculated using Pearson's, linear mixed effects, and sensitivity analysis models.
Results: The mean (SD) BMI was 30 (8.1) kg/m2, with 16 (30%) patients falling in the underweight/normal category (BMI <25 kg/m2), 10 (20%) overweight patients (25 kg/m2≤ BMI ≤ 30 kg/m2), and 24 (48%) patients considered obese (BMI >30 kg/m2). The mean (SD) AE heights for the left and right ears were 2.5 (1.11) and 2.6 (1.09), respectively. The results of the linear mixed-effects models indicated little evidence that BMI is associated with AE height when including all patients (partial R2 = 0.040) and when using BMI categories (partial R2 = 0.025).
Conclusion: Contrary to other structures within the lateral skull base, the relative prominence of the arcuate eminence does not correlate with BMI or any other demographic variables.
Keywords: BMI; arcuate eminence; middle fossa; obesity; skull base attenuation; superior semicircular canal.