上半规管裂综合征

Superior semicircular canal dehiscence syndrome

上半规管裂(SSCD)综合征是由于颅底上半规管骨质缺损所导致,特别是在弓状隆起处。骨迷路缺损导致在硬脑膜和膜迷路之间形成直接连通,形成可移动的第三窗,导致各种听觉和前庭症状。耳鸣和自听增强是最常见的听力学表现,头晕和不平衡是最常见的前庭表现。听力检查的结果根据疾病的严重程度而有所不同,低频传导性听力下降是常见的表现,骨传导阈值可能为负值。SSCD综合征患者患耳的前庭诱发肌源性电位(VEMP)反应阈值通常降低,也可能具有比正常VEMP更大的振幅。颞骨的高分辨率计算机断层(CT)扫描在确诊SSCD中起着重要作用。通常建议使用P9schl和Stenver重新格式化的视图。外科治疗适用于前庭症状和听力症状严重影响生活质量的患者,有两种主要的手术径路(颅中窝,乳突)和几种技术(封堵、加帽、重铺表面和组合法)。目前,没有足够的证据确切表明哪种手术方法或技术更好。通过颅中窝径路或经乳突径路的手术修复SSCD对听力和前庭症状的改善非常有效且并发症风险较低。

Superior semicircular canal dehiscence(SSCD)syndrome occurs as a result of a bony defect of the skull base involving the superior semicircular canal,particularly at the arcuate eminence.The bony labyrinthine defect creates a direct communication between the dura and the labyrinthine membranous structure and acts as a mobile third window which may result in various auditory and vestibular manifestations.Tinnitus and autophony are the most common audiological manifestations.Dizziness and disequilibrium are the most common vestibular manifestations.Audiometric findings vary based on the severity of the disease.Low-frequency conductive hearing loss is a common finding.Bone conduction thresholds may be negative.A patient with SSCD will typically have a lower Vestibular Evoked Myogenic Potentials(VEMP)threshold response in the affected ear and may also have a larger than normal VEMP amplitude.High-resolution computed tomography(CT)scan of temporal bone plays an important role in confirming the diagnosis of SSCD.P9 schl and Stenver reformatted views are often recommended.Surgical treatment is reserved for patients presenting with debilitating vestibular and auditory manifestations that substantially interfere with their quality of life.There are two main surgical approaches(middle fossa,trans-mastoid)and several techniques(plugging,capping,resurfacing and combination).Presently,there is insufficient evidence to clearly determine which surgical approach or technique is superior.Surgical repair of SSCD through either the middle cranial fossa approach or trans-mastoid approach is highly effective for auditory and vestibular symptom improvement and is associated with a low risk of complications.