The Bone Mineral Density of the Lateral Skull Base and its Relation to Obesity and Spontaneous Cerebrospinal Fluid Leaks.

OBJECTIVES

Evaluate the bone mineral density (BMD) of the lateral skull base by thin sliced computed tomography (CT) scans.Determine the BMD and its relation in patients who are obese or who have spontaneous cerebrospinal fluid (CSF) leaks.

STUDY

DESIGN

Blinded retrospective case control series.

SETTING

Tertiary care university setting.

PATIENTS: A control group consisting of age and sex matched non-obese patients were compared with obese and CSF leak patients.

INTERVENTIONS: Three blinded reviewers measured the BMD at multiple locations along the lateral skull base using thin sliced high-resolution CT scans. Additional BMD measurements were obtained from the temporal bone squamosal and otic capsule. The BMD was compared between the groups.

MAIN OUTCOME MEASURE: Lateral skull base BMD in patients who are obese or have CSF leaks as compared with non-obese controls.

RESULTS

Sixty-five (n = 65) patients were included in the study. The control group (n = 21) had a median density along the tegmen of 499.4 (178.8) HU, obese (n = 26) had an average HU of 559.5 (207.2), and CSF leak group (n = 18) had an average 472.9 (154.9), respectively (p = 0.35). The BMD in the temporal bone squamosa (p = 0.07) was not significantly different, however, the otic capsule was denser in the CSF leak group (p = 0.01) compared with the control group or the obese group. The intraclass correlation coefficient of the CT reviewers' measurements were moderate to strong (k = 0.69-0.99).

CONCLUSION

There appears to be no difference between the BMD of the lateral skull base as it relates to obesity or spontaneous CSF leaks compared with normal weight controls. These findings suggest the BMD does not have a significant role in the development of lateral skull base thinning or dehiscence leading to CSF leaks.