A New Perspective on the Cavernous Sinus as Seen through Multiple Surgical Corridors: Anatomical Study Comparing the Transorbital, Endonasal, and Transcranial Routes and the Relative Coterminous Spatial Regions

Abstract

Background: The cavernous sinus (CS) is a highly vulnerable anatomical space, mainly due to the neurovascular structures that it contains; therefore, a detailed knowledge of its anatomy is mandatory for surgical unlocking. In this study, we compared the anatomy of this region from different endoscopic and microsurgical operative corridors, further focusing on the corresponding anatomic landmarks encountered along these routes. Furthermore, we tried to define the safe entry zones to this venous space from these three different operative corridors, and to provide indications regarding the optimal approach according to the lesion’s location. Methods: Five embalmed and injected adult cadaveric specimens (10 sides) separately underwent dissection and exposure of the CS via superior eyelid endoscopic transorbital (SETOA), extended endoscopic endonasal transsphenoidal-transethmoidal (EEEA), and microsurgical transcranial fronto-temporo-orbitozygomatic (FTOZ) approaches. The anatomical landmarks and the content of this venous space were described and compared from these surgical perspectives. Results: The oculomotor triangle can be clearly exposed only by the FTOZ approach. Unlike EEEA, for the exposure of the clinoid triangle content, the anterior clinoid process removal is required for FTOZ and SETOA. The supra- and infratrochlear as well as the anteromedial and anterolateral triangles can be exposed by all three corridors. The most recently introduced SETOA allowed for the exposure of the entire lateral wall of the CS without entering its neurovascular structures and part of the posterior wall; furthermore, thanks to its anteroposterior trajectory, it allowed for the disclosure of the posterior ascending segment of the cavernous ICA with the related sympathetic plexus through the Mullan’s triangle, in a minimally invasive fashion. Through the anterolateral triangle, the transorbital corridor allowed us to expose the lateral 180 degrees of the Vidian nerve and artery in the homonymous canal, the anterolateral aspect of the lacerum segment of the ICA at the transition zone from the petrous horizontal to the ascending posterior cavernous segment, surrounded by the carotid sympathetic plexus, and the medial Meckel’s cave. Conclusions: Different regions of the cavernous sinus are better exposed by different surgical corridors. The relationship of the tumor with cranial nerves in the lateral wall guides the selection of the approach to cavernous sinus lesions. The transorbital endoscopic approach can be considered to be a safe and minimally invasive complementary surgical corridor to the well-established transcranial and endoscopic endonasal routes for the exposure of selected lesions of the cavernous sinus. Nevertheless, peer knowledge of the anatomy and a surgical learning curve are required.

Transorbital neuroendoscopic surgery for treatment of sphenoid wing meningiomas extending to the cavernous sinus: clinical implications and a technical illustration

“…8,[20][21][22] To address these challenges, radiosurgery and endoscopic methods have been increasingly adopted, offering less invasive alternatives. 12,[22][23][24] Notably, stereotactic radiosurgery, while effective, may be limited as a primary treatment due to tumor size and proximity to sensitive neurovascular structures. [16][17][18] The evolution of minimally invasive surgical techniques has revolutionized skull base surgery, with endoscopic approaches offering smaller incisions, reduced tissue trauma, and quicker recoveries.…”

“…[27][28][29] This approach, coupled with endoscopic transorbital surgery, forms the crux of modern skull base procedures. 15,21,23,24…”

Spheno-Orbital Meningiomas: The Rationale behind the Decision-Making Process of Treatment Strategy

“…The endoscopic endonasal technique affords great visualization of the orbital apex and optic canal and allows for the resection of tumors extended medially to the optic canal, pterygopalatine fossa, and the infratemporal fossa. The endoscopic transorbital approach (ETOA), first mainly adopted by ophthalmologists, allows for lesions affecting the paramedian aspect of the anterior and middle cranial fossae to be accessed [ 47 , 63 , 64 , 65 , 66 , 67 ]. This route addresses a similar anatomical target of the OC to the microsurgical transcranial approach, including lateral orbitotomy, but with different angles of attack, surgical freedom, and carrying peculiar benefits and limits [ 15 ].…”

Commentary: Transorbital approach to the cavernous sinus: an anatomical study of the related cranial nerves

“…For a long time, the cavernous sinus (CS) has been considered the “anatomical jewel box” and surgical “no man's land” due to the vital and highly functional neurovascular structures hosted within its boundaries and the high risks associated with surgery. Nevertheless, since the first pioneering study of Parkinson ( 1965 ), this deep-seated venous space in the central skull base has attracted great interest among neurosurgeons, who have investigated additional surgical routes from different access perspectives, including, more recently, the endoscopic transorbital approach (Dallan et al, 2017 ; Jung et al, 2022 ; Corvino et al, 2023d ; Evins et al, 2024 ).…”