Endoscopic endonasal transsellar approach for laterally extended pituitary adenomas: volumetric analysis of cavernous sinus invasion

The authors conducted a statistical analysis of surgical results of the endoscopic endonasal transsellar approach to provide quantitative indices for selection of the approach in the treatment of laterally extended pituitary adenomas. Surgical results of 25 patients with laterally extended pituitary adenomas of Knosp grade 3 or 4 were retrospectively analyzed. The removal rate was evaluated by the volumetric change of the lateral tumor compartment. The transsellar approach was used exclusively in all cases. Gross total removal of the lateral tumor compartment was achieved in 14 (56.0 %). Factors affecting the tumor removal through the transsellar approach were lateral tumor volume (p = 0.006), maximal distance to the cavernous sinus outer wall (p = 0.004) and history of previous surgery (p = 0.017). The cut-off values for the lateral tumor volume and maximal distance to the cavernous sinus outer wall predicting the gross total removal were 0.479 ml and 8.1 mm, respectively. The surgical complications of the transsellar approach included each case of anterior lobe function insufficiency and liquorrhea. The transsellar approach is adequate for removal of lateral tumor compartment in the majority of cases with laterally extended pituitary adenomas. The tumor compartments dorsal and ventral to the horizontal portion of the intracavernous carotid artery are amenable to the removal. But for removal of the tumor compartment lateral to the carotid siphon requires additional use of the parasellar approach.