Luntz M, Malatskey S, Braun J
Department of Otolaryngology-Head and Neck Surgery, Bnai Zion Medical Center, Faculty of Medicine, Haifa, Israel.
Am J Otol. 2000 Sep;21(5):686-9.
This study defines the three-dimensional location of the posterior-most point of the tympanic segment of the facial nerve (TSFN) relative to the posterior-most point of the short process of the incus, using ultrahigh-resolution computed tomography (CT) of the temporal bone.
STUDY DESIGN, SETTING, AND PATIENTS: Included were patients who had been referred for CT of the temporal bone for various reasons other than suspected pathologic conditions of the middle ear. The decision whether to include a patient in the study was based on the referring physician's referral note for the examination.
All of the patients underwent axial CT of the temporal bone, with consecutive slices of 1.1 mm width and 0.5-mm increments.
The posterior-most point of the short process of the incus was identified on axial CT and was superimposed onto a lower axial slice in which the posterior-most point of the TSFN was identified. Its shortest distance to the TSFN was measured. Afterward, the length of the TSFN that remained posterior to the perpendicular of the posterior-most point of the short process of the incus was measured by measuring the length of TSFN that could be seen posterior to the point of bisection of the line marking the shortest distance between the posterior-most point of the short process of the incus and the FN in the previous measurement. The measurements were performed on 30 normal temporal bones.
The shortest distance measured between the posterior-most point of the short process of the incus and the TSFN was, on average, 3.31 mm for all 30 ears (range 2-4.8 mm). The length of TSFN that could be seen posterior to the perpendicular of the most posterior point of the short process of the incus was, on average, 2.70 mm (range 1.80-3.90 mm).
In addition to defining the spatial location of the posterior-most point of the TSFN, this study also offers a practical method by which the surgeon can evaluate, preoperatively, how far medial to the incus and how much posterior to the posterior-most point of the short process of the incus the facial nerve is located.
本研究利用颞骨超高分辨率计算机断层扫描（CT）确定面神经鼓室段（TSFN）最后端相对于砧骨短突最后端的三维位置。
研究设计、地点和患者：纳入因中耳可疑病理状况以外的各种原因转诊进行颞骨CT检查的患者。是否将患者纳入研究的决定基于转诊医生的检查转诊记录。
所有患者均接受颞骨轴向CT扫描，连续切片宽度为1.1mm，增量为0.5mm。
在轴向CT上确定砧骨短突的最后端，并将其叠加到较低的轴向切片上，在该切片上确定TSFN的最后端。测量其到TSFN的最短距离。之后，通过测量在先前测量中标记砧骨短突最后端与面神经之间最短距离的线的二等分点后方可见的TSFN长度，来测量砧骨短突最后端垂线后方剩余的TSFN长度。对30个正常颞骨进行测量。
30只耳朵中，砧骨短突最后端与TSFN之间测量的最短距离平均为3.31mm（范围为2 - 4.8mm）。在砧骨短突最后点垂线后方可见的TSFN长度平均为2.70mm（范围为1.80 - 3.90mm）。
除了确定TSFN最后端的空间位置外，本研究还提供了一种实用方法，外科医生可通过该方法在术前评估面神经位于砧骨内侧多远以及砧骨短突最后端后方多远的位置。
