Characteristics and significance of the medial wall of cavernous sinus

Objective: To provide anatomic data of the medical wall of cavernous sinus(CS) for extended transsphenoidal approach. Methods: 20 cadaveric heads were studied under operating microscope, while HE and Mason staining were used to studied the structures of the medial wall of CS. MRI was used to analyze structures of normal sella region and compared with the results of specimens. Results: Sagittal dural layers were not found between the hypophysis and internal carotid artery (ICA) under the microscope, with the distance of them about 2.2 mm averagely. The upper part of the medial wall of the CS was the capsule of the hypophysis, along with loose circular fibrous tissue and adipose. The lower part of the medial wall of the CS was the periosteum covering the sphenoidal bone. On MRI images, we were unable to identify the dural wall separating the pituitary gland from the CS. Conclusions: The incomplete separation between the pituitary fossa and the cavernous sinus explains the high incidence of the extension of pituitary tumours to the CS, which is anatomic basis for the extension of the transsphenoidal approach to the CS.