Data_Sheet_2_Developing a Method to Precisely Locate the Keypoint During Craniotomy Using the Retrosigmoid Keyhole Approach: Surgical Anatomy and Technical Nuances.xlsx

Objective: To explore the precise location of the keypoint during craniotomy using the retrosigmoid keyhole approach.
Methods: This study included 20 dry skulls and 10 wet cadaveric specimens. On the inner surface of dry skulls, the junction between the inferior margin of the transverse sinus (ITS) and the posterior margin of the sigmoid sinus (TSJ) was marked. The keypoint (D) was identified as the TSJ's corresponding point on the external surface of the temporal mastoid process (MP). The distance from the keypoint to the top point of the digastric groove, mastoidale, and asterion were noted (AD, BD, CD, respectively). A method to accurately locate the keypoint was developed based on these relationships. The developed method was used on the wet cadaveric specimens to evaluate its accuracy, safety, rapidity, and minimal invasion.
Results: No significant difference was found between the AD, BD, and CD of the left and right sides. The drilling point was oriented on a straight line 12 mm above the top point of digastric groove, perpendicular to the Frankfort horizontal plane (FHP). In the cadaveric specimens, the operative area was clearly exposed. No venous sinus rupture occurred. The average craniotomy time was 28.74 ± 3.89 min.
Conclusions: A potentially safe, accurate, and rapid craniotomy procedure was developed with the added advantage of preserving the visibility of the operating field and preventing venous sinus injury.

研究目的：探索乙状窦后锁孔入路（retrosigmoid keyhole approach）开颅术中关键点的精准定位方法。
研究方法：本研究纳入20具干性颅骨标本及10具湿性尸体标本。在干性颅骨内表面，标记横窦下缘（inferior margin of the transverse sinus, ITS）与乙状窦后缘的交汇点（transverse-sigmoid junction, TSJ）；将关键点（D）定义为颞乳突部（temporal mastoid process, MP）外表面上与TSJ对应的点位。记录该关键点至二腹肌沟顶点、乳突点及星点的距离（分别记为AD、BD、CD）。基于上述测量关系建立了精准定位该关键点的方法，并将该方法应用于湿性尸体标本，以评估其准确性、安全性、快速性与微创性。
研究结果：左右侧的AD、BD、CD均无显著统计学差异。钻孔位点位于二腹肌沟顶点上方12mm的连线上，且与法兰克福水平面（Frankfort horizontal plane, FHP）垂直。在尸体标本实验中，手术区域显露清晰，未出现静脉窦破裂情况，平均开颅时长为28.74±3.89分钟。
研究结论：本研究成功建立了一种兼具安全性、精准性与快速性的开颅手术方案，其额外优势在于可维持手术视野清晰度，同时避免静脉窦损伤。