Tahir E, Bajin M D, Atay G, Mocan B Ö, Sennaroğlu L
Department of Otolaryngology - Head and Neck Surgery,Hacettepe University,Ankara,Turkey.
Department of Radiology,Hacettepe University,Ankara,Turkey.
J Laryngol Otol. 2017 Aug;131(8):676-683. doi: 10.1017/S0022215117001141. Epub 2017 Jun 1.
The bony cochlear nerve canal is the space between the fundus of the internal auditory canal and the base of the cochlear modiolus that carries cochlear nerve fibres. This study aimed to determine the distribution of bony labyrinth anomalies and cochlear nerve anomalies in patients with bony cochlear nerve canal and internal auditory canal atresia and stenosis, and then to compare the diameter of the bony cochlear nerve canal and internal auditory canal with cochlear nerve status.
The study included 38 sensorineural hearing loss patients (59 ears) in whom the bony cochlear nerve canal diameter at the mid-modiolus was 1.5 mm or less. Atretic and stenotic bony cochlear nerve canals were examined separately, and internal auditory canals with a mid-point diameter of less than 2 mm were considered stenotic. Temporal bone computed tomography and magnetic resonance imaging scans were reviewed to determine cochlear nerve status.
Cochlear hypoplasia was noted in 44 out of 59 ears (75 per cent) with a bony cochlear nerve canal diameter at the mid-modiolus of 1.5 mm or less. Approximately 33 per cent of ears with bony cochlear nerve canal stenosis also had a stenotic internal auditory canal and 84 per cent had a hypoplastic or aplastic cochlear nerve. All patients with bony cochlear nerve canal atresia had cochlear nerve deficiency. The cochlear nerve was hypoplastic or aplastic when the diameter of the bony cochlear nerve canal was less than 1.5 mm and the diameter of the internal auditory canal was less than 2 mm.
The cochlear nerve may be aplastic or hypoplastic even if temporal bone computed tomography findings indicate a normal cochlea. If possible, patients scheduled to receive a cochlear implant should undergo both computed tomography and magnetic resonance imaging of the temporal bone. The bony cochlear nerve canal and internal auditory canal are complementary structures, and both should be assessed to determine cochlear nerve status.
骨蜗神经管是内耳道底与蜗轴基部之间的空间，容纳蜗神经纤维。本研究旨在确定骨蜗神经管及内耳道闭锁和狭窄患者中骨迷路异常与蜗神经异常的分布情况，然后比较骨蜗神经管和内耳道直径与蜗神经状态。
本研究纳入了38例感音神经性听力损失患者（59耳），其中蜗轴中部的骨蜗神经管直径为1.5mm或更小。分别检查闭锁和狭窄的骨蜗神经管，中点直径小于2mm的内耳道被视为狭窄。回顾颞骨计算机断层扫描和磁共振成像扫描以确定蜗神经状态。
59耳中，蜗轴中部骨蜗神经管直径为1.5mm或更小的耳中有44耳（75%）出现耳蜗发育不全。约33%的骨蜗神经管狭窄耳同时伴有内耳道狭窄，84%有蜗神经发育不全或未发育。所有骨蜗神经管闭锁的患者均有蜗神经缺如。当骨蜗神经管直径小于1.5mm且内耳道直径小于2mm时，蜗神经发育不全或未发育。
即使颞骨计算机断层扫描结果显示耳蜗正常，蜗神经仍可能发育不全或未发育。如有可能，计划接受人工耳蜗植入的患者应同时进行颞骨计算机断层扫描和磁共振成像检查。骨蜗神经管和内耳道是互补结构，两者均应进行评估以确定蜗神经状态。
