Endoscopic Endonasal Transsphenoidal Transcavernous Transoculomotor Triangle Approach for Resection of an Invasive Pituitary Adenoma Extending Into the Parapeduncular Space Through the Cavernous Sinus.

BACKGROUND AND IMPORTANCE: A subset of invasive pituitary adenomas invade not only the medial wall of the cavernous sinus but can progress superiorly through the cavernous sinus roof at the oculomotor triangle and reach the subarachnoid parapeduncular space. We describe a series of 2 of 3 cases where an endoscopic endonasal approach was used to reach the parapeduncular space through the oculomotor triangle for tumor decompression. Images of the third case are presented.

CLINICAL PRESENTATION: Case 1: We present a 2-dimensional surgical video of a recurrent corticotroph adenoma post gamma knife radiotherapy which was invading the left cavernous sinus and extending into the left parapeduncular space. Histopathological examination revealed densely granulated corticotrophin adenoma. The patient had reduction in the serum cortisol level postoperatively and was induced into remission medically. Postoperative third nerve palsy recovered partially, and sixth nerve palsy recovered completely at the 3-month follow-up. Case 2: A case of recurrent silent corticotrophin adenoma invading the right parapeduncular space through the right cavernous sinus was operated through the same approach as case 1. Only a subtotal excision of the tumor in the cisternal space was possible. The patient developed a complete right third cranial palsy in the immediate postoperative period with near total recovery at the 6-month follow-up.

CONCLUSION: Endoscopic endonasal approach to the parapeduncular space through a transcavernous transoculomotor route is reasonably safe and effective, as long as key anatomic landmarks and structures are identified and preserved while using natural tumor corridors to achieve tumor clearance.