2026 Proffered Presentations
S024: MICROSURGICAL AND ENDOSCOPIC CHARACTERIZATION OF THE ANTEROINFERIOR WALL OF THE CAVERNOUS SINUS: A CADAVERIC STUDY AT THE INTERSECTION OF ANATOMICAL FOSSAE
Hao Tang, MD; Chiara Angelini, MD; Marco Obersnel, MD; Roberto Rubio, MD; Neurological surgery department of UCSF
Background: Conventionally, the boundaries of the cavernous sinus (CS) have been described as five walls: the roof, posterior, medial, lateral, and anterior. However, with the increasing use of inferolaterally expanded trans-cavernous approaches, the anatomical characteristics of the transition zone between the anterior wall (AWCS) and lateral wall (LWCS) — an area anatomically situated at the intersection of the middle cranial fossa, the superior orbital fissure, and the pterygopalatine fossa — remain insufficiently defined.
Methods: Five latex-injected cadaveric heads (10 sides) underwent expanded endoscopic endonasal exploration (inferolateral expanded trans-CS approach) of the AWCS and its anterior extension to the anteromedial temporal lobe. Microsurgical dissections of the middle cranial fossa were performed in two axial and two coronal specimens to identify anatomical landmarks corresponding to endoscopic findings. With the aid of a neuronavigation system, quantitative measurements were obtained for relevant structures.
Results: The study delineated the transitional configuration between the LWCS and AWCS, confirming the presence and boundaries of a sixth wall: the anteroinferior wall of the cavernous sinus (AIWCS). Its junction line with the AWCS, the annulus Zinn–prelingual ligament (ZLL), was consistently identified, serving as the basis for defining an “enhanced anteromedial triangle”. Quantitative analysis revealed that the AIWCS had a surface area of approximately 82.0 ± 9.1 mm², while the ZLL measured 13.8 ± 1.4 mm in length (Figs. 1–3). The composition and extent of the LWCS were further clarified, demonstrating that its inner layer lacks a continuous periosteal dura. These findings refine the anatomical model of the LWCS and enhance spatial understanding of the CS. In addition, a novel three-dimensional schematic model of the CS region was generated with transparent rendering to visualize complex relationships (Fig. 4).
Conclusion: Detailed anatomical characterization of the AIWCS within the transition zone between the LWCS and AWCS, together with an improved conceptual model of adjacent structures, provides more precise surgical localization through the enhanced anteromedial triangle endoscopic endonasal approach. These insights may help minimize unnecessary exposure and reduce the risk of iatrogenic injury during cavernous sinus surgery.
