Superior semicircular canal dehiscence mimicking otosclerotic hearing loss (original) (raw)
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Superior semicircular canal dehiscence (SSCD) can present with a variety of symptoms that can be predominantly auditory, predominantly vestibular or both. It can mimic a wide range of otological disorders, in particular otosclerosis-like stapes fixation. Our study revealed that, in 5.3% of our patients with clinically suspected otosclerosis, SSCD was detected in high-resolution multi-detector computed tomography (HRMDCT) of the temporal bone. We therefore emphasise the value of HRMDCT with reconstructions in the plane of the superior semicircular canal and perpendicular to the superior semicircular canal in the diagnostic work-up of each patient with a tentative diagnosis of otosclerosis-type stapes fixation. Where there are doubts, VEMP testing should be performed. We believe that a number of unexplained complications after an uneventful stapedotomy procedure might be explained by a pre-operatively undetected dehiscent superior semicircular canal and therefore unwarranted surgery. ...
Superior semicircular canal dehiscence (SSCD) is a rare entity recently described whose typical clinical symptomatology is represented by dizziness triggered by a variation of pressure. We reported a case of SSCD which was diagnosed thanks to computed tomography (CT) scan of the petrous bone conducted systematically in front of mixed deafness with normal eardrum. The SSCD was bilateral and was revealed by mixed deafness on the left side and perception deafness on the right with a normal eardrum without the notion of vertigo. The cervical vestibular evoked myogenic potential (cVEMP) and an ultra-high resolution CT scan of the petrous bones in coronal and sagittal sections allowed the diagnosis. The SSCD should be considered in the presence of any conductive or mixed hearing loss with a normal eardrum. The CT scan in coronal and sagittal submillimetric sections allows the diagnosis.
Posterior semicircular canal dehiscence in asymptomatic ears
Acta Oto-Laryngologica, 2010
Conclusions: This study revealed that, in the adult population, the final diagnosis of this entity can only be made by combining imaging with clinical tests. Objective: We developed the largest temporal bone multislice computed tomography (CT) scan study so far by including 410 cases to investigate the prevalence of posterior semicircular canal dehiscence in patients with symptoms unrelated to the inner ear. Methods: A prospective study was performed in 410 consecutive adult individuals who underwent temporal bone multislice CT scan examinations. Results: The prevalence of posterior semicircular canal dehiscence was determined to be 1.2%. No superior or lateral semicircular canal defect was detected in these five patients. All cases with posterior semicircular canal defect were male. In two cases the canal was located unilaterally, while in three cases the defects were present bilaterally. Otological examination and audiovestibular tests revealed no abnormal findings in any of the individuals.
Superior Canal Dehiscence Effect on Hearing Thresholds: Animal Model
Otolaryngology -- Head and Neck Surgery, 2011
Objective. Superior semicircular dehiscence syndrome is associated with vestibular symptoms and an air-bone gap component in the audiogram, apparently caused by the creation of a pathological bony "third window" in the superior semicircular canal. The aim of this study was to evaluate changes in auditory air-and bone-conduction thresholds to low-and highfrequency stimuli in an animal model of a bony fenestration facing the aerated mastoid cavity. Study Design. Anatomic, audiological. Setting. Tertiary university-affiliated medical center. Animals. A small hole was drilled in the bony apical portion of the superior semicircular canal facing the mastoid bulla/cavity, with preservation of the membranous labyrinth, in 5 adult-size fat sand rats. Main Outcome Measures. Auditory brain stem responses to clicks and 1-kHz tone bursts delivered by air and bone conduction before surgery, after opening the bulla, and after fenestration. Results. After fenestration, a significant air-bone gap was measured in response to clicks (mean ± standard deviation, 37 ± 5.8 dB) and bursts (mean ± standard deviation, 34 ± 14.5 dB). The gap was attributable solely to the significant deterioration in air-conduction thresholds, in the absence of a significant change in bone conduction thresholds. The pattern of auditory brain response changes closely resembled that reported for middle ear dysfunction, namely, an increase in absolute latency of waves I, III, and V without significant alterations in interpeak latency differences. Conclusions. Bony fenestration of the superior semicircular canal toward an aerated cavity in a rodent model mimics the auditory loss pattern of patients with superior semicircular dehiscence syndrome. The dehiscent membrane accounts for the auditory changes.
Journal of Vestibular Research
This paper describes the diagnostic criteria for superior semicircular canal dehiscence syndrome (SCDS) as put forth by the classification committee of the Bárány Society. In addition to the presence of a dehiscence of the superior semicircular canal on high resolution imaging, patients diagnosed with SCDS must also have symptoms and physiological tests that are both consistent with the pathophysiology of a ‘third mobile window’ syndrome and not better accounted for by another vestibular disease or disorder. The diagnosis of SCDS therefore requires a combination of A) at least one symptom consistent with SCDS and attributable to ‘third mobile window’ pathophysiology including 1) hyperacusis to bone conducted sound, 2) sound-induced vertigo and/or oscillopsia time-locked to the stimulus, 3) pressure-induced vertigo and/or oscillopsia time-locked to the stimulus, or 4) pulsatile tinnitus; B) at least 1 physiologic test or sign indicating that a ‘third mobile window’ is transmitting pr...
The pattern of hearing outcome following surgery of the semicircular canals
Laryngoscope Investigative Otolaryngology
To analyze demographic, clinical, surgical, and audiometric factors that may affect hearing outcome following surgery for the semicircular canals (SCC). Method: This is a retrospective case review of adults who underwent surgeries for superior SCC (SSCC), lateral SCC (LSCC), or posterior SCC (PSCC) and whose data were extracted and analyzed for factors affecting the hearing outcome in these procedures. Results: Thirteen patients underwent surgery for SSCC, seven cases for the LSCC, one for the PSCC, and one case of combined PSCC/SSCC surgery. The mean age was 49.8 AE 12 years (21-66). There was no difference between the preoperative and postoperative pure tone average (PTA) thresholds at 0.5-3 kHz. Higher thresholds were noted at 4, 6, and 8 kHz postoperatively. Deterioration (>10 dB) in the bone-conduction (BC) PTA was demonstrated in 3 of 22 (13.6%) cases with no significant difference in the demographic, clinical, surgical, and preoperative audiometric parameters relative to the cases without PTA BC change. A significantly larger difference in PTA BC (pre-vs. postoperative) was seen for males. Small effect size was noted for Air conduction (AC) PTA in males, and moderate effect size for Word Recognition Score (WRS) in surgery for the LSCC compare to SSCC. Conclusions: SCC surgeries carry a relatively low risk of deterioration in PTA BC. High frequency thresholds should also be included in postoperative hearing outcome assessment. Cases of LSCC for intractable Meniere's disease and surgery in males carry higher risk of poor postoperative hearing outcomes.
The relationship between the air-bone gap and the size of superior semicircular canal dehiscence
Otolaryngology - Head and Neck Surgery, 2009
To examine the relationship between the air-bone gap (ABG) and the size of the superior semicircular canal dehiscence (SSCD) as measured on a computed tomography (CT) scan. STUDY DESIGN: Case series with chart review. SETTING: Tertiary referral center. PATIENTS: Twenty-three patients (28 ears) diagnosed with SSCD. MAIN OUTCOME MEASURES: The size of the dehiscence on CT scans and the ABG on pure-tone audiometry were recorded. RESULTS: The size of the dehiscence ranged from 1.0 to 6.0 mm (mean, 3.5 Ϯ 1.6 mm). Six ears with a dehiscence measuring less than 3.0 mm did not have an ABG (0 dB). The remaining 18 ears showed an average ABG at 500, 1000, and 2000 Hz (AvABG 500-2000 ) ranging from 3.3 to 27.0 dB (mean, 11.6 Ϯ 5.7 dB). The analysis of the relationship between the dehiscence size and AvABG 500-2000 revealed a correlation of R 2 ϭ 0.828 (P Ͻ 0.001, quadratic fit) and R 2 ϭ 0.780 (P Ͻ 0.001, linear fit). Therefore, the larger the dehiscence, the larger the ABG at lower frequencies on pure-tone audiometry. CONCLUSIONS: In SSCD patients, an ABG is consistently shown at the low frequency when the dehiscence is larger than 3 mm. The size of the average ABG correlates with the size of the dehiscence. These findings highlight the effect of the dehiscence size on conductive hearing loss in SSCD and contribute to a better understanding of the symptomatology of patients with SSCD.
Journal of Medical Case Reports, 2011
Introduction This case illustrates that superior semicircular canal dehiscence syndrome can be associated with a "pseudo"-conductive hearing loss, a symptom that overlaps with the clinical appearance of otosclerosis. Case presentation We present the case of a 48-year-old German Caucasian woman presenting with hearing loss on the left side and vertigo. She had undergone three previous stapedectomies for hearing improvement. Reformatted high-resolution computed tomographic scanning and the patient's history confirmed the diagnosis of concurrent canal dehiscence syndrome. Conclusion Failure of hearing improvement after otosclerosis surgery may indicate an alternative underlying diagnosis which should be explored by further appropriate evaluation.