Patterns of invasion of the medial wall of the cavernous sinus by pituitary adenomas.

Objective: With their growing experience in endoscopic transcavernous approaches, the authors have observed that pituitary adenomas have distinct patterns of invasion into the medial wall of the cavernous sinus (MWCS). In this study, they aimed to describe the different patterns of MWCS invasion and their relevance for pituitary surgery.

Methods: Based on a review of 144 patients with 159 cavernous sinus (CS) explorations, the authors described three patterns of MWCS invasion: focal invasion, wall thickening, and wall destruction. Demographics, previous surgery, size, hormonal status, consistency, CS compartment invasion, invasion of the carotico-clinoid ligament (CCL), carotid adherence, gross-total resection (GTR) of intracavernous tumor, endocrinological remission (ER), and complications (vascular injury, cranial nerve palsy, CSF leakage, and hematoma) were evaluated.

Results: The most frequent pattern of MWCS invasion was wall destruction (47.2%), followed by wall thickening (28.9%) and focal invasion (23.9%). All cases of focal invasion were contained within the wall, whereas 59% of the wall-thickening and 100% of the wall destruction cases had intracavernous tumor (p < 0.001). Overall, GTR was achieved in 87.4% of cases and ER was achieved in 80.6% with surgery alone. Focal invasion was most associated with functioning adenomas (92%) and low Knosp grade (95%). Invasion of the CCL, adherence of the MWCS to the carotid artery, and fibrous consistency were found in 15%-20% of cases. GTR was achieved in all cases and ER in 93% with no complications associated with MWCS resection. Wall thickening was also found predominantly in functioning adenomas (83%) with low Knosp grade (72%), and often in recurrent cases (46%). Carotid adhesion was significantly more frequent (61%), as was CCL invasion (44%) and fibrous consistency (46%). GTR was achieved in 98% and ER in 82%, with transient postoperative diplopia in 7% of cases, all with intracavernous tumor. Wall destruction occurred almost exclusively in macroadenomas (96%) with high Knosp grades (59%) and no hormonal secretion (55%). Invasion of the CCL, fibrous consistency, and carotid adherence were found in less than one-third of the cases. GTR was achieved in 75% and ER in 65%, with postoperative diplopia in 11% of cases.

Conclusions: Pituitary adenomas may invade the MWCS in three distinct patterns, each with particular tumor characteristics and a differential degree of technical difficulty and clinical outcomes.