Lateral Skull Base Attenuation in Patients with Anterior Cranial Fossa Spontaneous Cerebrospinal Fluid Leaks

Abstract

Objective (1) Determine if patients with anterior fossa spontaneous cerebrospinal fluid (SCSF) leaks demonstrate lateral skull base bone attenuation. (2) Examine the relation between body mass index (BMI; kg/m2) and skull base thickness. Study Design Retrospective cohort study. Setting Tertiary care hospital. Subjects and Methods Retrospective review from 2004 to 2013 identified 96 patients with anterior cranial fossa SCSF leaks. A control group was identified from a consecutive series of clinic patients. Controls had no history of chronic sinonasal or temporal bone pathology and were divided according to BMI into nonobese (<30 kg/m2) and obese (≥30 kg/m2) groups. Composite skull base thickness was calculated for lateral and anterior subsites through predefined points according to previously published protocols. Results Thirty-two patients were included in each group. Composite lateral skull base thickness was less in patients with SCSF leaks(0.7 ± 0.1 mm) when compared with nonobese controls (0.8 ± 0.1 mm, P = .004); no differences were apparent when SCSF leaks were compared with obese controls (0.7 ± 0.1 mm, P = .99). A direct relation was observed between anterior skull base and lateral skull base thickness ( r = 0.48, P < .0001). An inverse correlation was noted between BMI and lateral skull base ( r =−0.40, P < .0001). Conclusions Patients with anterior fossa SCSF leaks demonstrate attenuation of the lateral skull base. A significant correlation between anterior skull base thickness and lateral skull base thickness was observed. BMI was inversely related to lateral skull base thickness. Taken together, SCSF leaks are associated with obesity, which appears to be partly responsible for diffuse skull base erosion observed in patients with this condition.