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.

Colloid Cyst: Revision of Third Ventricular Zones for Risk Stratification of Hydrocephalus.

OBJECTIVE: We sought to reclassify the "anatomic risk zones of colloid cysts" as proposed by Beaumont et al, by proposing newer landmarks, and to assess predictive value for the risk of occurrence of hydrocephalus with the new classification compared with the old. METHODS: A retrospective cohort of 122 cases of colloid cyst of third ventricle were categorized into zones 1, 2, or 3 based on Beaumont's classification (old zone) and our classification (new zone) based on radiologic images. We attempted to recategorize these zones by assigning new anatomic landmarks. The difference in zonal distribution of colloid cyst and association with hydrocephalus was studied using the 2 methods of zonal classification. RESULTS: Per the old zone classification, 3/122 patients were in zone 2, whereas 21/122 were in zone 2 per the new zone classification. The new zone method had a higher specificity (36.21% vs. 5.263 %) and positive predictive value (63.37% vs. 54.23%) for occurrence of hydrocephalus in patients with colloid cyst. The Spearman correlation showed better correlation with the new method for occurrence of hydrocephalus (rho = 0.4 [P < 0.00000] vs. 0.2 [P = 0.011]). CONCLUSIONS: Symptomatic colloid cysts are more likely to develop hydrocephalus and sudden acute deterioration. The colloid cyst risk score is a step towards objective decision making, with scope for modification such as the one that we have attempted with new zone classification to achieve superior prognostic ability.