CT imaging of superior semicircular canal dehiscence: added value of reformatted images

Superior semicircular canal dehiscence (SSCD) syndrome may present with various symptoms. CT scans previously interpreted as normal may show SSCD, especially if special reconstructions tailored for superior canal evaluation are added.

The purpose of this study was to investigate prevalence of SSCD, its length and its correlation with symptoms in patients who had previously undergone temporal bone CT examination that was reported normal and to demonstrate the importance of reformatted images in the diagnosis of SSCD.

We retrospectively reviewed 108 patients who had undergone temporal bone CT examination for various symptoms and were reported as normal. High-resolution temporal bone CT imaging was performed with 1 mm slice thickness in the transverse plane. Each of the superior semicircular canals was evaluated in the plane of Pöschl and Stenver reformatted images together with axial images.

Ninety-three patients were included in the study. Nineteen patients with semicircular canal dehiscence were detected. The mean age of the study group was 45 years. Radiologic evidence of SSCD occurred in 23 of 186 temporal bones with a radiologic prevalence of 12%. The most common symptoms in dehiscent patients were vertigo, hearing loss and tinnitus. Defect lengths varied between 1 mm and 6.5 mm.