Endoscopic Endonasal Transsphenoidal Approach to Large and Giant Pituitary Adenomas: Institutional Experience and Predictors of Extent of Resection

Objective: While the use of endoscopic approaches has become increasingly accepted in the resection of pituitary adenomas, limited evidence exists regarding the success of this technique for patients with large and giant pituitary adenomas. This study presents the outcomes of a large cohort of patients with large and giant pituitary adenomas who underwent endoscopic endonasal transsphenoidal surgery (EETS) at our institution. It focuses on identifying factors that can predict extent of resection, and hence aid in developing guidelines and indications for the use of EETS versus open craniotomy approaches to large and giant pituitary adenomas.

Methods: We reviewed 487 patients who underwent EETS resection of sellar masses. From this group, 73 consecutive patients with large and giant pituitary adenomas (defined as maximum diameter ≥ 3 cm and tumor volume ≥ 10 cm³) who underwent EETS between January 2006 and May 2012 were included in the study. Clinical presentation, radiographic studies, laboratory investigations, tumor pathology data, clinical outcomes, extent of resection measured by volumetric analysis, and complications were analyzed.

Results: Mean preoperative tumor diameter in this series was 4.1 cm and volume was 18.43 cm³. The average resection rate was 82.9%, corresponding with a mean residual volume of 3.15 cm³. Gross total resection was achieved for 16 patients (24.2%), near total in 11 (16.7%), subtotal in 24 (36.4%), and partial in 15 (22.7%). In 73.0% of patients, visual acuity improved, and 23.8% were unchanged. Visual fields were improved in 61.8% and unchanged in 38.2%. Overall, 27 patients (37.0%) experienced a total of 32 complications. The most common complications were sinusitis (13.7%) and CSF leak (9.6%). Six patients underwent subsequent radiation therapy due to aggressive tumor histopathology. No deaths occurred in this cohort of patients. Statistically significant predictors of extent of resection included highest Knosp Grade (P = 0.000), preoperative tumor volume (P = 0.025), preoperative maximum tumor diameter (P = 0.002), hemorrhagic component (P = 0.049), posterior extension (P = 0.000), and sphenoid sinus invasion (P = 0.005). Anterior extension, lateral extension beyond the carotids in the intracranial component, optic nerve compression, cystic components, cell type, and tumor markers were not statistically significant predictors of extent of resection.

Conclusions: EETS is an effective treatment method for patients with giant pituitary adenomas, which results in high (>80%) rates of resection and improvement in visual function. It is not associated with high rates of major complications and is safe when performed by experienced surgeons. The preoperative Knosp Grade, tumor volume, tumor diameter, hemorrhagic components on MRI, posterior extension, and sphenoid sinus invasion may allow prediction of extent of resection.