Radiological prevalence of superior and posterior semicircular canal dehiscence in children☆
Introduction
Superior semicircular canal dehiscence syndrome (SCDS) was first described by Minor in 1998 and results from an absence of bone overlying the superior semicircular canal in the petrous roof [1]. SCDS classically presents with “third window phenomenon” symptoms including aural fullness, conductive hyperacusis (i.e. pulsatile tinnitus, autophony) and pressure or sound induced vertigo [1].
Diagnosis of SCDS is based on clinical history and examination in combination with radiological evidence of dehiscent bone plus characteristic audiological and vestibular function test findings, most notably reduced threshold and high amplitude vestibular evoked myogenic potentials (VEMP). High resolution computed tomography (CT) is an integral diagnostic feature of SCDS. It is well recognized that not all patients with evidence of SCD will develop SCDS; the discrepancy may be due to errors in imaging accuracy or that additional critical events are required to make the bony dehiscence symptomatic. Direct clinical visualization of the petrous roof is not feasible, and therefore CT remains the most accepted method of assessing bone integrity in this area.
The prevalence of bony dehiscence in children is important to our understanding of the etiology of this condition. Some authors advocate a congenital predisposition, which may subsequently lead to symptomatic clinical disease in adulthood, whilst others propose that intact bone in childhood is later thinned by osteopenic processes [2], [3] or microtrauma [4].
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. In addition we assessed correlation with congenital malformation, younger age and relationship with adjacent venous sinuses.
Section snippets
Study design
Retrospective case series. Analysis was made of all CT scans of the temporal bone undertaken at British Columbia Children's Hospital (Vancouver, Canada), followed by a retrospective chart review of any patient found to have canal dehiscence. Approval was obtained from the University of British Columbia Children's and Women's Research Ethics Board (Research protocol: H12-00582).
Inclusion criteria:
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Temporal bone CT scans for any indication.
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Scans performed between Jan 2007 and Jan 2012.
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Age of
Results
Over the 5-year period reviewed, 408 CT scans were retrieved, equating to 816 temporal bones. 167 temporal bones were excluded: 31 for congenital or acquired disruption/malformation of the vestibular organ, 136 due to inadequate images (see Section 2 for explanation of exclusion criteria). This left 649 temporal bones from 334 individuals for analysis (see Fig. 2). The mean age of the cohort was 7.6 years (range 7 months–17.4 years). 66 children were under the age of three years (19.8%). There
Discussion
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.
A limitation of any study based
Conclusion
We found evidence of superior and posterior canal dehiscence, and thinning of the bone without frank dehiscence, within a large series of children undergoing CT scanning of the petrous temporal bone. While the canal dehiscence syndrome remains rare in children, the presence of bony defects in this population supports a congenital predisposition leading to clinical manifestation of the syndrome at a later age.
Financial disclosures
None.
Conflicts of interest
None.
Acknowledgments
The authors would like to acknowledge Ms. Rachelle Dar Santos Moshfeghi, Research Assistant, and Yogesh Thakur, Medical Physicist, for assistance with reformatting CT protocols.
References (26)
- et al.
Anatomo-radiological study of the superior semicircular canal dehiscence radiological considerations of superior and posterior semicircular canals
Eur. J. Radiol.
(2010) - et al.
Semicircular canal dehiscence in the pediatric population
Int. J. Pediatr. Otorhinolaryngol.
(2009) - et al.
Coronal computed tomography prevalence of superior semicircular canal dehiscence
Otolaryngol. Head Neck Surg.
(2003) - et al.
Sound- and/or pressure-induced vertigo due to bone dehiscence of the superior semicircular canal
Arch. Otolaryngol. Head Neck Surg.
(1998) - et al.
Dehiscence of the superior semicircular canal: a review of the literature on its possible pathogenic explanations
Eur. Arch. Otorhinolaryngol.
(2013) - et al.
Superior semicircular canal dehiscence: congenital or acquired condition?
Am. J. Neuroradiol.
(2011) - et al.
CT evaluation of bone dehiscence of the superior semicircular canal as a cause of sound- and/or pressure-induced vertigo
Radiology
(2003) - et al.
CT imaging of superior semicircular canal dehiscence: added value of reformatted images
Acta Otolaryngol.
(2010) - et al.
Superior semicircular canal dehiscence: positive predictive value of high-resolution CT scanning
Eur. Arch. Otorhinolaryngol.
(2008) - et al.
Prevalence of radiographic semicircular canal dehiscence in very young children: an evaluation using high-resolution computed tomography of the temporal bones
Pediatr. Radiol.
(2012)
Incidence of semicircular canal dehiscence in Singapore
Brit. J. Radiol.
The prevalence of superior canal dehiscence syndrome as assessed by temporal bone computed tomography imaging
Acta Otolaryngol.
Semicircular canal dehiscence in HR multislice computed tomography: distribution, frequency, and clinical relevance
Eur. Arch. Otorhinolaryngol.
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Presentation: The results of this study were presented at the Canadian Society of Otolaryngology Head & Neck Surgery (CSO-HNS) Annual Meeting on June 2nd 2013 in Banff, Alberta, Canada and the 28th Barany Society Meeting on May 28th 2014 in Buenos Aires, Argentina.