Volumetric Study of Nonfunctioning Pituitary Adenomas: Predictors of Gross Total Resection

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 gross total resection (GTR) of a clinically nonfunctioning pituitary adenoma through an endoscopic endonasal approach. METHODS: Across 100 surgeries, we analyzed epidemiologic and clinical data, radiologic 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 cm(3) (range, 0.5-58 cm(3)), the median maximum diameter was 27.3 mm (range, 7-67 mm), and the Knosp grade was 0 in 1 patient, 1 in 23%, 2 in 31%, 3 in 23% and 4 in 22% of patients. In the multivariate logistic regression analysis, we found 3 factors that significantly predicted the chances of a successful GTR: previous sellar surgery, Knosp grade, and tumor signal in the T2-weighted magnetic resonance imaging scan. Another 10 radiologic variables were analyzed and had no effect on the EOR. CONCLUSIONS: Knosp grade (P < 0.001; odds ratio [OR], 25.65; 95% confidence interval, 7.19-91.52) is the most predictive factor for performing a GTR of nonfunctioning pituitary adenoma. Previous pituitary surgery (P = 0.023;OR, 5.81) and an isointense T2-weighted signal (P = 0.034; OR, 3.75) also negatively influenced the chances of GTR. We highlight the influence of T2-weighted signal in the chances of GTR.

Automated summary

Knosp grade is the most predictive factor for achieving a gross total resection of nonfunctioning pituitary adenoma, while previous pituitary surgery and an isointense T2-weighted signal negatively influence the chances of success. The T2-weighted signal plays a significant role in determining the likelihood of a successful gross total resection.