Location of the stapedius muscle with reference to the facial nerve in patients with unilateral congenital aural atresia: implication for active middle ear implants surgery

Abstract

Background: Detailed investigations of the stapedial muscle (SM) in congenital aural atresia (CAA) patients have yet to be adequately conducted.

Objectives: To assess image variations in the mastoid segment of the facial nerve (FN) and SM in CAA.

Materials and methods: A total of nine patients comprising of 9 ears with unilateral CAA were studied. The courses of the FN and SM were evaluated from the basic point to 1 mm intervals between the mastoid portion of FN, and measured from the mean X and Y values in each group.

Results: The atresia side of FN among the Y values showed significant differences compared to the contralateral side. In terms of the SM, there were no significant differences in both the X and Y values. The stapedial muscle of the CAA patients was located medially to the FN. Conversely, the distance from the PSC to the FN revealed no significant differences with regard to the X and Y values for each group.

Conclusion: The current observations revealed that the SM is located more posterior to the FN in CAA patients, and this is mainly attributed to the laterally and anteriorly displaced FN.

Chinese abstract

背景：对先天性耳道闭锁（CAA）患者进行镫骨肌（SM）的详细研究尚待充分开展。

目的：探讨CAA患者的面神经乳突段（FN）和SM的影像变化。

材料与方法：对9例9耳单侧CAA患者的临床资料进行分析。FN和SM的病程从FN乳突部之间的基点到1 mm的间隔进行评估, 并根据每组的平均X和Y值进行测量。

结果：Y值中FN闭锁侧与对侧相比, 有显著性差异。至于SM, X和Y值均无显著差异。CAA患者的镫骨肌位于FN的内侧。相反, 从PSC到FN的距离显示, 各组的X和Y值没有显著差异。

结论：目前的研究显示, CAA患者的SM位于FN后方, 这主要是由于FN侧向和向前移位所致。

Keywords:

• Aural atresia
• unilateral
• facial nerve
• stapedial muscle
• computed tomography
• active middle ear implant

Informed consent

This study was approved by the Tohoku University Hospital Institutional Review Board (IRB protocol number: 2018-1-662).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Japan Society for the Promotion of Science grant number [18K16872].