Picavet V, Govaere E, Forton G
Department of Otolaryngology, Head and Neck Surgery, Heilig Hart General Hospital Roeselare, Roeselare, Belgium..
B-ENT. 2009;5(2):83-8.
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. The typical feature of the conductive hearing loss due to SSCD compared to otosclerosis is an air-bone gap which is much more prominent at low frequencies than at high frequencies.
上半规管裂（SSCD）可表现出多种症状，主要为听觉症状、主要为前庭症状或两者皆有。它可模仿多种耳科疾病，尤其是耳硬化症样的镫骨固定。我们的研究表明，在临床疑似耳硬化症的患者中，5.3%的患者在颞骨高分辨率多探测器计算机断层扫描（HRMDCT）中检测到SSCD。因此，我们强调在对每例初步诊断为耳硬化症型镫骨固定的患者进行诊断检查时，HRMDCT在上半规管平面及垂直于上半规管平面重建的价值。如有疑问，应进行前庭诱发肌源性电位（VEMP）测试。我们认为，在镫骨手术过程顺利后出现的一些无法解释的并发症，可能是由于术前未检测到的上半规管裂，从而导致了不必要的手术。与耳硬化症相比，SSCD导致的传导性听力损失的典型特征是气骨导差，在低频比高频更为明显。
