Transnasal endoscopic anatomy and approaches to the cavernous sinus

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The goal of the current study is to describe the transnasal endoscopic anatomy of the cavernous sinus and to provide the surgical approaches to this area. Six silicon-injected adult cadaveric heads (12 sides) were dissected through endoscopic endonasal approach. The cavernous sinus and adjacent structures were exposed; detailed anatomies were demonstrated. High-quality pictures were produced. The cavernous sinus had four walls, namely medial, lateral, posterior and superior walls. Five venous spaces within the sinus were identified by their relation to the carotid artery; those were the medial, lateral, posterosuperior, posteroinferior and anterolateral compartments. Three branches arising from the cavernous segment of internal carotid artery from proximal to distal were meningohypophyseal trunk, inferolateral trunk and McConnell capsular artery. Cavernous sinuses communicated each other by intercavernous sinuses, as well as basilar sinus in middle line, and connected with superior and inferior petrosal sinuses. The third and fourth nerves coursed in superior part of the lateral wall of the cavernous sinus; Meckel's cave located in the posteroinferior part of the lateral wall of the cavernous sinus; V1 sloped to the superior orbital fissure along the lateral wall; the sixth nerve entered the posteroinferior compartment then passed through the internal carotid artery and reached to superior orbital fissure. The approaches to the cavernous sinus included trans-sphenoid-sellar-medial cavernous sinus (medial to the internal carotid artery) and trans-ethmoid-pterygoid-sphenoid-lateral cavernous sinus (lateral to the internal carotid artery). Trans-sphenoid-sellar-medial cavernous sinus approach was able to expose medial compartment and posterosuperior compartment and part of posteroinferior compartment. Trans-ethmoid-pterygoid-sphenoid-lateral cavernous sinus approach was able to expose anteroinferior compartment, lateral cavernous sinus and cranial nerves in lateral wall. An understanding of the complex relationships of the cavernous segment of internal carotid artery and cranial nerves in cavernous sinus is paramount for surgically dealing with the disease involved cavernous sinus and adjacent region.