Semicircular canal dehiscence in HR multislice computed tomography: distribution, frequency, and clinical relevance

Abstract

The literature about bony defects in the semicircular canal system is highly inconsistent. Therefore, we analyzed a series of 700 high-resolution multislice CT examinations of the temporal bone for semicircular canal dehiscencies. An unselected group of ENT patients with different clinical symptoms and variable age was chosen. We found semicircular canal dehiscence in 9.6% of temporal bones, superior semicircular canal was affected mostly (8%), less common posterior semicircular canal (1.2%); only in 3 cases (0.4%), lateral semicircular canal showed dehiscence. In 60% of SSC dehiscence, we registered bilateral manifestation. The so-called "third mobile window" in semicircular canal dehiscence causes a great variety of clinical symptoms like vertigo, nystagmus, oscillopsies, hearing loss, tinnitus and autophonia. Comparison with anatomic studies shows that CT examination implies the risk of considerable overestimation; this fact emphasizes the important role of clinical and neurophysiological testing.

Can MRI Replace CT in Evaluating Semicircular Canal Dehiscence?

“…20 This relatively low SSC and PSC dehiscence incidence leads to wide 95% confidence interval results for sensitivity and positive predictive value. Specificity and negative predictive value confidence intervals are much smaller but will also require confirmation with a larger population study.…”

Diagnostic performance of reformatted isotropic thin-section helical CT images in the detection of superior semicircular canal dehiscence

“…9,[12][13][14] However, significant differences have been found between autopsy-proven versus CT-detected SSC dehiscence. [15][16][17] It has been proposed that reformatted CT images oriented parallel (plane of Po¨schl) and orthogonal (plane of Stenver) to the plane of the SSC may improve the sensitivity and specificity in detecting SSC dehiscence. [10][11][12][13] The aim of our study was to establish the diagnostic performance of 0.5-mm collimation temporal bone helical CT in the diagnosis of SSC dehiscence syndrome comparing the accuracy of reformatted images oriented in the standard axial and coronal planes, as compared with the accuracy of reformatted images oriented parallel and perpendicular to the SSC.…”

“…12,19,20 The surgical treatment consists in surgically obliterating the defect in the superior canal by using either a trans-mastoid or middle fossa approach. 17,21 Previous studies suggest that radiologic evidence of SSC dehiscence may be overestimated, indicating that a dehiscence at the arcuate eminence may be observed in asymptomatic patients. 14,16,17 It should be pointed out, however, that these studies are based on older scanning protocols with 1.0-mmthick direct transverse and coronal images, or with 1.0-mm-thick reformatted images in the plane of Po¨schl and Stenver.…”

Radiological prevalence of superior and posterior semicircular canal dehiscence in children

“…Previous studies have examined canal dehiscence radiologically [4][5][6][7][8][9][10][11][12][13][14][15]19] but report a large range in overall prevalence (see Table 4). Reasons for this discrepancy include the lack of an agreed definition of true dehiscence, the use of differing CT scanning technologies with variable slice thickness and lower spatial resolution, failure to reformat in the plane of the canals and only having one reviewer.…”

“…Previous prevalence studies have employed a variety of radiological methods, resulting in a wide range of published prevalence rates [4][5][6][7][8][9][10][11][12][13][14][15][16]. We aimed to obtain a better estimate of the true prevalence by utilizing higher resolution imaging techniques in a larger sample size than has previously been studied with strict definition criteria.…”