Lateral Skull Base Attenuation in Superior Semicircular Canal Dehiscence and Spontaneous Cerebrospinal Fluid Otorrhea.

OBJECTIVES (1) To quantitatively assess the lateral skull base thickness in patients with superior semicircular canal dehiscense (SSCD) using a standardized and validated radiographic measure and to compare it with that of a population with spontaneous cerebrospinal fluid otorrhea (CSFO). (2) To analyze demographic and clinical factors associated with skull base thickness in the SSCD group. STUDY DESIGN Case series with chart review. SETTING Tertiary neurotologic referral center. SUBJECTS AND METHODS Based on computed tomography imaging of the tegmen, mean skull base thickness was calculated for 16 patients with radiographic and clinical SSCD. Similar measures were performed in 4 comparison groups consisting of adults with spontaneous CSFO (n = 33), as well as 3 control groups recruited from our adult cochlear implant database: 30 obese controls (body mass index [BMI] >30 kg/m(2)), 11 overweight controls (BMI, 25-30 kg/m(2)), and 20 normal weight controls (BMI <25 kg/m(2)). RESULTS The SSCD group had a significantly lower mean BMI (28.6 kg/m(2)) than the spontaneous CSFO group (37.7 kg/m(2); P = .0007). The mean skull base thickness of SSCD patients was 17% thinner than that of the CSFO group, 31% thinner vs obese controls, 49% thinner vs overweight controls, and 45% thinner vs normal weight controls. These differences were all statistically significant (P < .05). CONCLUSION Patients with SSCD have a marked thinning of the lateral skull base, more so than patients with spontaneous CSF otorrhea and control groups with different BMIs. Skull base attenuation in SSCD patients did not correlate with BMI.