CTandMRImagingoftheInnerEarandBraininChildrenwithCongenitalSensorineuralHearingLoss概要.ppt

CT and MR Imaging of the Inner Ear and Brain in Children with Congenital Sensorineural Hearing Loss 先天性感音神经性聋患儿内耳及脑部CT、MRI表现  PART Ⅱ第二部分 Complete Labyrinthine Aplasia 迷路未发育 Complete labyrinthine aplasia, also known as Michel aplasia (because it was first described by Michel in 1863), is the most severe form of inner ear deformity; it is caused by developmental arrest of the otic placode during the 3rd gestational week 迷路未发育又称为米歇尔畸形（Michel畸形），1863年由米歇尔首次提出，是最严重的内耳畸形，是由于妊娠第3周听基板发育停止引起的 The condition is extremely rare, accounting for only 1% of all inner ear malformations 这种畸形非常少见，占全部内耳畸形的1% Complete labyrinthine aplasia is defined by the complete absence of inner ear structures (Fig 4a) 内耳结构完全缺如确定为迷路未发育 A narrow, atretic IAC is seen on high-resolution CT images (Fig 4b), and the eighth cranial nerve is not visualized on MR images (Fig 4c) HRCT图像上可看到内耳道狭窄、闭锁，MRI上看不到第8对颅神经 These abnormalities may be unilateral or bilateral 这些异常可单侧或双侧发生 In patients with unilateral complete labyrinthine aplasia, the contralateral inner ear structures are often dysplastic 单侧迷路未发育的患者，对侧内耳结构常发育不良  Figure 4a Complete labyrinthine aplasia. (a) Axial high-resolution CT image shows the absence of inner ear structures . Note the flat medial wall of the middle ear cavity (arrow) and the hypoplastic petrous bone (*). 图4a 内耳未发育。（a）横轴位HRCT图像显示内耳结构缺如。中耳腔内侧壁平坦（箭）、颞骨岩部发育不全（星号）  Figure 4b Complete labyrinthine aplasia. (b) Coronal CT image shows an atretic IAC (arrow). 图4b 内耳未发育。（b）冠状位CT图像显示内耳道闭锁（箭）  Figure 4c Complete labyrinthine aplasia. (c) Sagittal MR image obtained in a plane perpendicular to the IAC depicts a single nerve (arrow) within the small IAC. Combined with the findings in a and b, this feature is suggestive of absence of the eighth cranial nerve图4c 内耳未发育。（c）垂直于内耳道平面重建的矢状位MRI图像显示细小的内耳道内只有一支神经（箭）。结合a、b，这个特征提示第8对颅神经缺如 Multiple associated abnormalities have been described in structures arising from the otic capsule 可出现听囊起源结构的多发伴随畸形 Hypoplasia of the petrous bone,