title: Semicircular canal dehiscence: frequency and distribution on temporal bone CT and its relationship with the clinical outcomes.
abstract: OBJECTIVE
  In this study, we aimed to investigate the frequency of SCD and its distribution and relationship with clinical outcomes on thin-section CT of the temporal bone.
  
  
  METHODS
  Digital temporal bone CT images of 850 consecutive patients (1700 temporal bone CTs, 5100 SCs) who presented with a range of complaints such as vertigo, deafness, ear pain, fullness, and discharge between January 2008 and December 2011 were re-evaluated. Axial and oblique coronal reconstruction images of the temporal bone were made with a reconstruction thickness of 0.5mm. Additionally, superior SC was evaluated in two perpendicular planes.
  
  
  RESULTS
  Out of 850 patients, 70 had completely normal temporal bone CT. Ninety-three patients had at least one SCD. In the temporal bone-based evaluation, 119 (26 bilateral, 67 unilateral) of 1700 temporal bones (7%) showed dehiscence. The SC-based evaluation revealed 125 SCD (2.5%) in 5100 SCs. The total number and rates of SCD were as follows: superior 103 (82.4%), posterior 13 (10.4%), and lateral nine (7.2%). Twenty of the 93 patients with SCD (21.5%) revealed no other findings on their temporal bone CTs. We determined a significant correlation between vestibular complaints, conductive hearing loss and SCD but there was no correlation between mixed, sensorineural hearing loss and SCD.
  
  
  CONCLUSIONS
  We determined the frequency of SCD in 11% of patients and 7% of temporal bones. With regards to the distribution, the superior SC showed the highest dehiscence rate (82.4%). We found a significant correlation between vestibular symptoms, conductive hearing loss and SCD.
authors.affiliation: Department of Radiology, Ondokuz Mayis University, Faculty of Medicine, Samsun, Turkey. muzafel@yahoo.com.tr
authors.forename: Muzaffer
authors.initials: M
authors.lastname: Elmali
authors.forename: Ahmet Veysel
authors.initials: AV
authors.lastname: Polat
authors.forename: Harun
authors.initials: H
authors.lastname: Kucuk
authors.forename: Sinan
authors.initials: S
authors.lastname: Atmaca
authors.forename: Ahmet
authors.initials: A
authors.lastname: Aksoy
mesh_terms: D017677:Age Distribution; D005260:Female; D006801:Humans; D007762:Labyrinthitis / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D008297:Male; D015995:Prevalence; D011379:Prognosis; D015203:Reproducibility of Results; D012307:Risk Factors; D012665:Semicircular Canals / Q000000981:diagnostic imaging*; D012680:Sensitivity and Specificity; D017678:Sex Distribution; D013701:Temporal Bone / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data*; D014421:Turkey / Q000453:epidemiology
keywords: Canal dehiscence, third window lesions; Hearing loss; Superior semicircular canal dehiscence; Temporal bone CT