Coronal computed tomography prevalence of superior semicircular canal dehiscence.
OBJECTIVE
The relatively new clinical entity superior canal dehiscence syndrome (SCDS) is diagnosed by clinical symptoms and signs. Coronal computed tomography (CT) has been used to confirm the diagnosis. A consecutive series of temporal bone CT scans was reviewed to define the prevalence of a dehiscent-appearing superior semicircular canal.


METHODS
Temporal bone CT scans performed over a 2-year period at a university-based tertiary referral center were reviewed independently by 3 individuals. Scans were excluded if coronal images were not obtained or reconstructed from axial images. Prevalence figures for dehiscent-appearing superior semicircular canal were determined by consensus. Medical records of selected individuals with a dehiscent-appearing canal were reviewed for study indications and otologic symptoms.


RESULTS
A dehiscent-appearing superior semicircular canal was seen in 9% of studies. Correlation among examiners was greater than 94%. Medical records indicated symptoms suggestive of or compatible with the diagnosis of SCDS in rare cases.


CONCLUSIONS
The prevalence of a dehiscent-appearing superior semicircular canal on coronal CT of the temporal bones performed with 1.0-mm collimation is substantially greater than that predicted by temporal bone histologic study. Clinical symptoms compatible with the diagnosis were seldom recorded, suggesting low specificity. The high sensitivity and low specificity of CT scan create a risk for overdiagnosis of SCDS if the coronal CT scans are not correlated with clinical symptoms.
Bobby R. Alford Department of Otorhinolaryngology and Communicative Sciences, Baylor College of Medicine, 6550 Fannin, Suite SM1727, Houston, TX 77030, USA.
Robert A
RA
Williamson
Jeffrey T
JT
Vrabec
Newton J
NJ
Coker
Marlin
M
Sandlin
D000293:Adolescent; D000328:Adult; D000368:Aged; D004427:Ear Diseases / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology*; D007758:Ear, Inner / Q000000981:diagnostic imaging / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009999:Ossification, Heterotopic / Q000000981:diagnostic imaging / Q000473:pathology; D004856:Postural Balance / Q000502:physiology*; D015995:Prevalence; D012665:Semicircular Canals / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D013577:Syndrome; D013701:Temporal Bone / Q000000981:diagnostic imaging / Q000473:pathology; D014057:Tomography, X-Ray Computed; D014717:Vertigo / Q000175:diagnosis / Q000503:physiopathology*