Section Editor: Sandy Cheng-Yu Chen, M.D.
Taipei Medical University Hospital, Taipei, Taiwan
Figure Caption
Focal loss of bone overlying the superior semicircular canals (SSC) is known as SSC dehiscence syndrome (SSCD). In SSCD, the inner ear effectively acquires a “third mobile window”, which acts as an abnormal communication between the middle cranial fossa and the SSC, resulting in vestibular dysfunction. A common manifestation of SSCD is the Tullio phenomenon, referring to sound-induced disequilibrium or visual field movements. High-resolution CT of the temporal bone in the coronal plane reveals focal SSC defects (A, long arrows). Better advantage is illustrated in short axis oblique reformats (B and C, arrowheads) that allow demonstration of greater than 2mm defect for diagnosis.