Endoscopic endonasal resection of the medial wall of the cavernous sinus: 2D operative video

Background: Resection of the medial wall of the cavernous sinus (MWCS) has been associated with improved outcomes and may be considered in selected cases. However, this procedure remains technically challenging due to complex anatomy of the cavernous sinus (CS) and its relationship with the cavernous internal carotid artery (ICA), oculomotor nerve, and venous plexus. The MWCS corresponds to the lateral portion of meningeal dural layer, whereas the periosteal dural layer covers the pituitary gland anteriorly and inferiorly and forms the anterior wall of the CS. This video demonstrates endoscopic endonasal resection of the MWCS. Case Description: A 51-year-old woman presented with clinical symptoms and laboratory findings consistent with endogenous hypercortisolism. Preoperative MRI demonstrated an 8 mm right-sided sellar lesion (Knosp grade 3A on the right side, grade 0 on the left side). During surgery, the MWCS was explored due to suspected invasion on preoperative MRI and intraoperative concern for tumor attachment. A binostril endoscopic endonasal approach was performed. After bilateral sphenoidotomy, sphenoid septations were drilled. The parasellar ICA was unroofed. The sellar floor was removed. Following middle clinoidectomy, the periosteal layer was identified. Using an anterior-to-posterior technique, the anterior wall of the CS was opened first, and the durotomy was extended medially toward the sella. The periosteal layer was then dissected from the meningeal layer, and the meningeal layer was sharply opened to expose the adenoma and pituitary gland. Venous bleeding was controlled with suction, warm irrigation, and powder hemostatics. The adenoma was dissected from the dura, and the lateral tumor margin was resected. The inferior hypophyseal artery and caroticoclinoidal ligament were coagulated and divided. The MWCS was mobilized and resected. Gross total resection was achieved. The postoperative course was uneventful, biochemical remission was achieved with no new pituitary hormone deficits, and the patient was discharged on postoperative day 1 without complications or cranial nerve deficits. Histopathological examination confirmed a corticotroph adenoma with invasion of the resected MWCS. At the 3-month follow-up, the patient’s preoperative symptoms had resolved, and she had lost approximately 35 lb. Conclusion: Identification of key structures and mastery of patient-specific anatomy are essential for safe and effective MWCS resection through an endoscopic endonasal approach.