Calvarium Thinning in Patients with Spontaneous Cerebrospinal Fluid Leaks of the Anterior Skull Base

Objectives/Hypothesis: Patients with spontaneous cerebrospinal fluid leaks (sCSF-L) of the temporal bone have isolated calvarial and skull base thinning that is independent of obesity. This study determines if anterior skull base (ASB) sCSF-L patients also have calvarial thinning. Study Design: Retrospective Cohort Study. Methods: This was a retrospective cohort study of ASB sCSF-L patients compared to nonobese (body mass index [BMI] < 30 kg/m²) and obese (BMI ≥ 30) control groups. Twenty-one patients in the ASB sCSF-L group and 25 patients in each control group were included. Calvarium and extracranial zygoma thicknesses were measured bilaterally with blinded, standardized, volumetric analysis. Results: ASB sCSF-L patients had a mean (SD) age of 50.43 (10.19) years, an average (SD) BMI of 38.81 (8.92) kg/m², and most were female (85.71%). The calvarium in patients with ASB sCSF-L was significantly thinner than the nonobese (2.55 mm [0.77] vs. 2.97 [0.67] mm; P =.006; 95% confidence intervals [CI], 0.12–0.30; Cohen d, 0.58) and obese control groups (2.55 [0.77] vs. 2.92 [0.76] mm; P =.02; 95% CI, 0.05–0.34; Cohen d, 0.66). The calvarium thickness of the nonobese patients was not significantly different from the obese patient controls (2.97 [0.67] vs. 2.92 [0.76] mm, P =.9). The extracranial zygoma was not significantly different among the groups (analysis of variance, P =.33). Conclusions: ASB sCSF-L patients have isolated calvarial thinning that is independent of obesity. Like lateral skull base sCSF-L patients, these data suggest that the additional obesity-associated intracranial process contributes to skull thinning. Level of Evidence: 4 Laryngoscope, 131:1271–1276, 2021.