Safe Corridor to Access Clivus for Endoscopic Trans-Sphenoidal Surgery: A Radiological and Anatomical Study

PurposePenetration of the clivus is required for surgical access of the brain stem. The endoscopic transclivus approach is a difficult procedure with high risk of injury to important neurovascular structures. We undertook a novel anatomical and radiological investigation to understand the structure of the clivus and neurovascular structures relevant to the extended trans-nasal trans-sphenoid procedure and determine a safe corridor for the penetration of the clivus.MethodWe examined the clivus region in the computed tomographic angiography (CTA) images of 220 adults, magnetic resonance (MR) images of 50 adults, and dry skull specimens of 10 adults. Multiplanar reconstruction (MPR) of the CT images was performed, and the anatomical features of the clivus were studied in the coronal, sagittal, and axial planes. The data from the images were used to determine the anatomical parameters of the clivus and neurovascular structures, such as the internal carotid artery and inferior petrosal sinus.ResultsThe examination of the CTA and MR images of the enrolled subjects revealed that the thickness of the clivus helped determine the depth of the penetration, while the distance from the sagittal midline to the important neurovascular structures determined the width of the penetration. Further, data from the CTA and MR images were consistent with those retrieved from the examination of the cadaveric specimens.ConclusionOur findings provided certain pointers that may be useful in guiding the surgery such that inadvertent injury to vital structures is avoided and also provided supportive information for the choice of the appropriate endoscopic equipment.研究目的：脑干手术入路需穿透斜坡（clivus）。经内镜斜坡入路手术难度较高，且存在损伤重要神经血管结构的高风险。本研究开展了一项创新性的解剖学与放射学调查，旨在明确与扩大经鼻经蝶窦手术相关的斜坡及神经血管结构特征，并确定穿透斜坡的安全通道。 研究方法：本研究对220名成人的计算机断层血管造影（computed tomographic angiography, CTA）图像、50名成人的磁共振（magnetic resonance, MR）图像以及10具成人干性颅骨标本的斜坡区域进行观测。对CT图像实施多平面重建（multiplanar reconstruction, MPR），并在冠状位、矢状位及轴位平面上分析斜坡的解剖学特征。利用影像数据测算斜坡及颈内动脉、岩下窦等神经血管结构的解剖学参数。 研究结果：对入组受试者的CTA及MR图像分析显示，斜坡厚度可用于确定手术穿透深度，而矢状中线至重要神经血管结构的距离则决定了穿透宽度。此外，CTA与MR影像数据与尸体标本检查结果具有一致性。 研究结论：本研究结果可为手术操作提供指导参考，有助于避免对关键结构造成意外损伤，同时可为内镜手术器械的选型提供支持性依据。