Volumetric study of nonfunctioning pituitary adenomas: predictors of gross total resection

ABSTRACT Objective Despite the efforts made to determine the achieved resection grade after pituitary adenoma surgery, there is a high level of disagreement among all the available classifications and measurement methods used. Our objective is to identify the factors that preoperatively could predict a GTR of an NFPA through an endoscopic endonasal approach. Methods Across 100 surgeries, we analyzed epidemiological and clinical data, radiological relevant data, extent of resection (EOR) and postoperative outcomes. The EOR was measured objectively through an accurate volumetric analysis. Results The median presurgical volume was 8.58 ml (range 0.5-58 cm3), the median maximum diameter was 27.3 mm (range 7-67 mm), and the Knosp grade was 0 in 1 case, 1 in 23%, 2 in 31%, 3 in 23% and 4 in 22% of cases. In the multivariate logistic regression analysis, we found three factors that significantly predicted the chances of a successful GTR: previous sellar surgery, Knosp grade and tumor signal in the T2-weighted MRI scan. Another ten radiologic variables were analysed and had no effect on the EOR. Conclusions Knosp grade (p