Pituitary adenoma extended to the basilar sinus: Lessons from anatomical and radiological studies (Experimental Research).

Pituitary adenoma (PA) with basilar sinus extension has often been overlooked in previous studies. In this study, 47 cases of such a subset of PAs were introduced, and the surgery-related anatomy and strategies were discussed.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.The connection between the cavernous sinus (CS) and the basilar sinus is 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%), including 12 cases of limb hypertrophy, 3 cases of central obesity, and 2 cases of menstrual changes, 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%) was the most common postoperative complication, but it was alleviated in two patients during postoperative follow-up.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.