经乳突后锁孔入路磨除部分岩骨显露中颅窝的内镜解剖学研究

Endoscopic anatomic study of the middle fossa via retromastoid keyhole approach through drilled petrous ridge

目的探讨神经内镜下经乳突后锁孔入路密除部分岩骨显露中颅窝的范围、可行性及适应证。方法采用苏州大学附属第二院神经外科解剖实验室提供的不分性别、完整、无缺损的成人尸头标本8具（16侧），模拟神经内镜下经乳突后锁孔入路磨除内听道上结节及岩尖显露中颅窝，观察最大的显露范围，标识Parkinson三角的边界，显露Meckel囊、海绵窦外侧壁包含的解剖结构，并测量乙状窦后缘中点至中颅窝各重要解剖结构的距离、Parkinson三角的边长。结果经乳突后锁孔入路可显露小脑脑桥角、脑干腹外侧、小脑幕切迹间隙、岩斜区及海绵窦外侧壁；可显露的中颅窝解剖标志包括：三叉神经节、滑车神经及外展神经海绵窦段、动眼神经岩床段、颈内动脉海绵窦后曲部及交通段、后交通动脉。乙状窦后缘中点至内听道上结节、三叉神经半月节、颈内动脉海绵窦后曲段的距离分别为（34．4±2．1）inin、（54．5±2．9）mm、（65．2±3．1）mm；Parkinson三角边长分别为（19．0±2．9）mm、（16．2±2．0）mm、（8．0±2．3）mm。结论神经内镜下经乳突后锁孔入路磨除部分岩骨增加中颅窝的有效显露，适合处理大部分后颅窝肿瘤、动脉瘤等病变，并能够完成主体位于后颅窝，小部分侵及中颅底病变的处理。

Objective To observe the range of exposure, indications and feasibility of retromastoid keyhole approach through drilled petrous ridge to the middle fossa. Methods The eight adult eadareric heads in this study were provided by the anatomy laboratory of the second affiliated hospital of Soochow Univer sity. Simulated surgeries via retromastoid keyhole approach with assistance of neuroendoscope were performed on 8 adult cadaverie heads （16 sides） fixed by formalin and the maximal ranges of exposure were observed. The neuroendoscope was used to observe anatomical structures in the middle fossa and identify the limits of the Parkinson＇s triangle. The distances from the posterior border of junction of lateral sinus and sigmoid sinus to middle fossa and the length of all sides of Parkinson＇s triangle were measured. Results Identified under endoscope, the exposure range of this approach included cerebellopontine angel （CPA）, ventrolateral brainstem, tentorial incisure, petroclival region and lateral wall of cavernous sinus. The exposed anatomical structures in the middle fossa included trigeminal ganglion, cavernous segment of trochlear and abducent nerve, petroclinoid segment of oculomotor nerve, posterior curve segment of internal carotid artery （ICA） in cavernous sinus, communicating segment of 1CA and posterior communicating artery （PCoA）. Measurement results suggested that the distances from the midpoint of posterior border of sigmoid sinus to suprameatal tubercle, trigeminal ganglion, posterior curve segment of ICA were 34.4±2. 1 mm, 54. 5±2. 9 mm and 65.2±3.1 ram, respectively. The lengths of all sides of Parkinson＇ s triangle were 19.0±2.9 mm, 16. 2±2. 0 mm and 8.0±2.3 mm, respectively. Conclusion The retromastoid keyhole approach via drilled petrous ridge leads to feasible exposure of the middle fossa under neuroendoscope, which could be applied in operations of most lesions in the posterior fossa such as tumors and aneurysms as well as those mainly in the posterior fossa and minorly affecting the middle fossa.