We found a series of Knosp grade 3A–4 pituitary adenomas in the posterior areas of the cavernous sinus (CS), a triangular-like structure on axial MRI. In this study, we dissected the surrounding neurovascular structure, discussed the surgical approach, and analyzed outcomes for patients with this invasion into this area. Eight embalmed adult cadaveric specimens were prepared for this study to demonstrate in detail the surgical anatomy related to this triangular-like structure. We used the “two points and one line” method to determine the surgical approach, and 35 cases with this area invasion were retrospectively reviewed. According to the endoscopic and microsurgical anatomy, the triangular-like structure appearing on the axial MRI is correlated with a square-based pyramid structure in the CS, and the upper surface is the posterior portion of the oculomotor triangle. A total of 37 posterior areas of the CS were involved in 35 patients. The accuracy of the “two points and one line” method in predicting the surgical approach is 86.5% (32/37). All three patients with Knosp 3A underwent gross total resection (GTR). Twenty (62.5%) patients with Knosp 4 underwent GTR, 9 (28.1%) patients underwent subtotal resection, and 3 (9.4%) patients underwent partial resection. Preoperative symptoms were alleviated to varying degrees, and no worsening occurred. Postoperative complications included two (5.7%) cases of cerebrospinal fluid leakage, one (2.9%) case of meningitis, two (5.7%) cases of permanent diabetes insipidus, and three (8.6%) cases of transient cranial nerve palsy. The “two points and one line” method is of great value in predicting the surgical approach of pituitary adenomas with CS invasion. The anatomic description of this particular square-based pyramid structure in the CS refines the understanding of pituitary adenomas with CS invasion.

我们在海绵窦 (CS) 的后部区域发现了一系列 Knosp 3A-4 级垂体腺瘤，这是轴向 MRI 上的三角形结构。在这项研究中，我们解剖了周围的神经血管结构，讨论了手术方法，并分析了侵入该区域的患者的结果。为这项研究准备了八个经过防腐处理的成人尸体标本，以详细展示与这种三角形结构相关的手术解剖结构。我们采用“两点一线”方法确定手术入路，回顾性分析了35例侵犯该区域的病例。根据内窥镜和显微外科解剖学，轴向 MRI 上出现的三角形结构与 CS 中的方形金字塔结构相关，上表面是动眼神经三角的后部。35 名患者共涉及 CS 的 37 个后部区域。“两点一线”法预测手术入路的准确率为86.5%（32/37）。所有三名患有 Knosp 3A 的患者都接受了全切除术 (GTR)。20 名（62.5%）Knosp 4 患者接受了 GTR，9 名（28.1%）患者接受了次全切除术，3 名（9.4%）患者接受了部分切除术。术前症状均有不同程度的缓解，未见加重。术后并发症包括脑脊液漏2例（5.7%）、脑膜炎1例（2.9%）、永久性尿崩症2例（5.7%）和短暂性脑神经麻痹3例（8.6%）。“两点一线”法对预测CS浸润垂体腺瘤手术入路具有重要价值。CS 中这种特殊的基于方形的金字塔结构的解剖学描述完善了对 CS 侵袭的垂体腺瘤的理解。