Endoscopic endonasal transsphenoidal surgery for sellar lesion:an anatomic study

Objective The endoscopic surgical anatomy of sphenoidal sinus and sellar region was studied to establish an anatomic basis for endoscopic endonasal transsphenoidal surgery. Methods The posterior wall of sphenoidal sinus and sellar region were dissected and observed under endoscope via an endonasal transsphenoidal approach on 8 adult cadaveric heads. Results The posterior bony wall of the sphenoidal sinus is subdivided into 9 compartments with # shape line. The three compartments in the midline are named as optic chiasm, the sella and clivus from the superior to the inferior. The two symmetrical bilateral compartments are named as optic canal, parasellar cavernous sinus and paraclival cavernous sinus from the superior to the inferior. The common anatomic landmarks in the posterior bony wall of sellar-type sphenoidal sinus contain the clival indentation, the optic canal protuberance, the internal carotid artery protuberance and the optic nerve-internal carotid artery recess. Optic-carotid recess is a consistent bony anatomic landmark, which is bordered by the optic nerve, the cavernous sinus, the internal carotid artery in the cavernous sinus, and the orbital apex. The connecting line between bilateral optic-carotid recesses is the projection of the tuberculum sellae. The bony defects are frequently found in the parasellar or cavernous sinus compartment. Conclusions The # shape subdivision for the posterior wall of the sphenoidal sinus is suitable for bony layer, dural layer and intracranial layer. This classification simplifies the complicated anatomical structure of the posterior wall and the identification and orientation of lesion in this area. Optic-carotid recess is a very important anatomic landmark.