Pituitary Adenoma Extended to the Basilar Sinus: Lessons from Anatomical and Radiological Study（An Experimental Research）

Purpose Pituitary adenoma (PA) with basilar sinus extension has been neglected in previous literature. In this study, 47 cases of such a subset of PAs were introduced, and the surgery-related anatomy and strategies were discussed. Methods The medical records of patients with basilar sinus extension were analyzed retrospectively. Four human head specimens were used for epoxy sheet plastination, and five were used for endoscopic endonasal dissection. Results The connection between the cavernous sinus (CS) and the basilar sinus is located in the superomedial space of the gulfar segment abducens nerve and beneath the petrosphenoidal ligament. The characteristic manifestation on enhanced sagittal MR images is the “triangle” sign, which means that the high signal in the basilar sinus disappears and is replaced by triangular-like tumor protrusions without destruction of the clivus or dorsum sellae. The most common symptom was endocrine dysfunction (17 patients; 36.2%), with 88.2% of patients experiencing remission postoperatively. According to the dataset, 83% of patients achieved total resection through the endoscopic endonasal approach. Abducens nerve palsy (3 patients, 6.4%) were the most common postoperative complications, but two patients were alleviated during postoperative follow-up. Conclusion The basilar sinus can serve as a potential breakthrough path through the CS compartments for PA invasion. With a clear anatomical understanding of the invasion corridor for this subset of PAs and corresponding surgical techniques, PAs can be safely removed without increasing surgical risk.