OBJECTIVE To quantitatively measure surgical degree of freedom (SDF) to the anterior communicating artery (AComA) complex via removal of the orbital rim. Comparisons of SDF quadrants were made between a supraorbital and standard frontotemporal pterional craniotomy according to the surgeons' geometric microscope compass-based views. METHODS Eleven latex-injected formalin-fixed cadaveric heads; 14 sides (eight unilateral and three bilateral) were dissected. Standard frontotemporal pterional and subsequent supraorbital craniotomy approaches were conducted in each specimen. Point "0" was allocated as a point 1 cm distal to the ipsilateral A1 and A2 junction of AComA. The tip of a 10-cm long pointer was used to locate point 0. The base of the pointer stick was maneuvered outside the craniotomy in eight compass directions, with the most peripheral points expressed as target points 1-8. The center of this octagon was attributed point C. A pyramid was established by connecting the points 0, C, and 2 neighboring target points. A frameless stereotaxic instrument was used as a three-dimensional digitizer to measure pyramid volume. Each neighboring two pyramids form a hexagonal cone and was expressed as a surgical freedom quadrant (cm3). The quadrants are depicted counterclockwise (surgeons view) as orbital-nasal, vertex-nasal, vertex-temporal, and orbital-temporal. RESULTS Total SDF obtained via supraorbital and pterional approaches were 122.8 ± 109.66 and 159.94 ± 93.65, respectively (mean ± SD cm3; supraorbital < pterional by 30.2%). Supraorbital to pterional, in the orbital-nasal quadrant was 21.9 ± 35.5 and 13.04 ± 8.7, vertex-nasal 31.3 ± 28.5 and 16.7 ± 13.7, vertex-temporal 39.5 ± 42.14 and 60.4 ± 4.7, and orbital-temporal 30.14 ± 42.14 and 70.01 ± 42.14, respectively (mean ± SD cm3). In the vertex-nasal quadrant, the supraorbital approach provides a 47.3% increase in SDF compared to the standard frontotemporal pterional craniotomy approach. CONCLUSION Given that the AComA complex is located more nasally and the surgeon's view is more vertex, we propose that a supraorbital craniotomy allows a more contralateral portion of the AComA complex to be visualized during dissection.

中文翻译：

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定量测量前交通动脉复合体手术自由度-额颞ter肌和眶上颅骨开颅术的比较研究；实验室研究。

目的通过去除眼眶边缘来定量测量前交通动脉（AComA）复合体的手术自由度（SDF）。根据外科医生基于几何显微镜指南针的观点，在眶上和标准额颞颞部开颅手术之间比较了SDF象限。方法十一只乳胶注射的福尔马林固定尸体头。解剖了14个侧面（8个单侧和3个双侧）。在每个标本中进行标准的额颞p肌和随后的眶上开颅手术。将点“ 0”分配为距AComA的同侧A1和A2交汇点1厘米远的点。用一个10厘米长的指针的尖端来定位点0。在8个指南针方向上，在开颅手术之外操纵指针杆的底部，最外围的点表示为目标点1-8。该八边形的中心归因于点C。通过连接点0，C和2个相邻目标点建立了金字塔。使用无框立体定位仪作为三维数字化仪，以测量金字塔的体积。每个相邻的两个金字塔形成一个六边形锥，并表示为手术自由象限（cm3）。象限沿逆时针方向（外科医生视图）描绘为鼻-眶，鼻-顶点，颞-颞和眶-颞。结果通过眶上和肋骨入路获得的总SDF分别为122.8±109.66和159.94±93.65（平均值±SD cm3；眶上<眼睑部30.2％）。眶上至翼状，在眼眶鼻象限中为21.9±35.5和13.04±8.7，对鼻鼻窦为31.3±28.5和16.7±13.7，顶点时态分别为39.5±42.14和60.4±4.7，轨道时态为30.14±42.14和70.01±42.14（均值±SD cm3）。与标准额颞颞部开颅手术相比，在眶鼻象限中，眶上入路的SDF增加了47.3％。结论鉴于AComA复合体位于鼻侧，外科医生的视野更靠近顶点，因此我们建议眶上开颅手术可在解剖过程中可视化AComA复合体的更多对侧部分。