建立侧颅底表面坐标系定位乙状窦-横窦交汇区的解剖与临床研究

目的 探讨准确定位横窦-乙状窦交汇区内下点（IMTS）侧颅底表面坐标系统的建立方法及该坐标系统在乙状窦后入路开颅术中的应用价值。方法 收集成人颅骨标本42例（男20例，女22例），以颧骨额突与颧弓上缘交点（A点）、颧弓上缘与乳突上嵴交点（B点）和乳突尖（C点）为基本点；连接A、B两点，并向枕部方向在侧颅骨表面作一延长线，定义为X轴，向后（枕部方向）为正方向；经C点在颅骨表面作X轴的正交垂线，定义为Y轴，向下为正方向；定义两线的交点为原点。定义IMTS点到X轴的垂直距离为IMTS-y（mm），到Y轴的垂直距离为IMTS-x（mm）。2014年7月至2015年3月采用上述坐标系统定位IMTS，并开展乙状窦后入路开颅术9例，其中听神经瘤5例，面肌痉挛3例和桥小脑角区表皮样囊肿1例。结果 IMTS-x:男性左侧为（21.76±3.14）mm，右侧为（24.28±4.19）mm；女性左侧为（22.25±2.72）mm，右侧为（24.41±3.52）mm。IMTS-y:男性左侧为（4.27±2.27）mm，右侧（4.58±2.36）mm；女性左侧为（2.38±2.48）mm，右侧为（3.65±3.67）mm。统计分析显示，男性右侧IMTS-x明显大于左侧（P<0.05）；男性左侧IMTS-y明显小于女性（P<0.05）；其余均无统计学差异（P>0.05）。本组9例患者术中均准确暴露出横窦下缘和乙状窦后缘。结论 在乙状窦后入路开颅手术中，该坐标系统能准确定位IMTS，有实用价值。

Anatomic and clinical study of localization of the transverse-sigmoid sinus junction using a coordinate system on the lateral surface of the cranial base

Objective To establish a coordinate system to locate precisely the inferomedial point of the transverse-sigmoid sinus junction (IMTS) for craniotomy via retrosigmoid approach. Methods Forty-two adult skulls (84 sides; male, 20; female, 22) were used in this study. The X-axis was defined by point A, which was the point of intersection of the upper edge of the zygomatic arch and the frontal process of the zygomatic bone, and point B, which was the point of intersection of the upper edge of the zygomatic arch and the supramastoid crest. The Y-axis was defined by the line which was perpendicular to the X-axis and extended across the tip of the mastoid. The x and y coordinates of IMTS (IMTS-x and IMTS-y) were measured in this coordinate system. Then the data were used for the localization of the IMTS in the surgery via the retrosigmoid approach. Results IMTS-x of male left side was (21.76±3.14)mm and right (24.28±4.19)mm. IMTS-x of female left side was (22.25±2.72)mm and right (24.41±3.52)mm. IMTS-y of male left side was (4.27±2.27)mm and right (4.58±2.63)mm. IMTS-y of female left side was (2.38±2.48)mm and right (3.65±3.67)mm. There was significant difference in IMTS-x between the right and left sides in the male skulls (P<0.05). There was significant difference in left side IMTS-y between the male and female skulls (P<0.05). During the craniotomy, the coordinate system helped to locate the IMTS correctly. Conclusion This novel reference coordinate system is a reliable and practical method to identify the IMTS during the craniotomy via the retrosigmoid approach.