Temporal bone anatomy characteristics in superior semicircular canal dehiscence

Marrigje A. de Jong; David J. Carpenter; David M. Kaylie; Erin G. Piker; Dennis O. Frank-Ito

doi:10.3760/j.issn.1672-2930.2017.04.004

摘要：Introduction: Superior semicircular canal dehiscence (SCD) remains difficult to diagnose despite advances in high-resolution computed tomography(HRCT) imaging. We hypothesize possible associations between gross temporal bone anatomy and sub-millimeter pathology of thesemicircular canals, which may supplement imaging and clinical suspicion. This pilot study investigates differences in gross temporal boneanatomic parameters between temporal bones with and without SCD.Methods: Records were reviewed for 18 patients referred to an otology clinic complaining of dizziness with normal caloric stimulation resultsindicative of non-vestibular findings. Eleven patients had normal temporal bone anatomy while seven had SCD. Three-dimensional reconstructionof every patient's temporal bone anatomy was created from patient-specific computational tomography images. Surface area (SA),volume (V), and SA to V ratios (SA:V) were computed across temporal bone anatomical parameters.Results: SCD temporal bones have significantly smaller V, and larger temporal bone SA. Mean (±SD) V was 21,484 ± 3,921 mm3 in temporalbones without SCD and 16,343 ± 34,471 mm3 for those with SCD. Their respective SA were 13,733 ± 1,603 mm2 and 18,073 ± 3,002 mm2.Temporal bone airspaces and lateral semicircular canals did not demonstrate significant differences where SCD was and was not present. Plots ofMVwarm response against computed SCD temporal bone anatomic parameters (SA, V and SA:V) showed moderate to strong correlations:temporal bone SA:V (r = 0.64), temporal bone airspace V (r = 0.60), temporal bone airspace SA (r = 0.55), LSCC SA (r = 0.51), and LSCC-to-TM Distance (r = 0.65).Conclusions: This analysis demonstrated that SCD is associated with decreased temporal bone volume and density. The defect in SCD does notappear to influence caloric responses.