Application of the "three points and three lines" method to accurately open sellar floor in microscopic transsphenoidal surgery of pituitary adenomas.

OBJECTIVE: This study proposes to analyze the sellar floor morphology of patients with pituitary adenoma, and to find a simple yet reliable method to determine the location of bone window opening. METHOD: Clinical information of 144 consecutively admitted patients was retrospectively analyzed. Enhanced MR image of the mid-sagittal plane was selected as the reference for classifying the sellar floor. Intra-operative tumor locating, extent of tumor resection, and follow-up results were analyzed for different types of sellar floor. Briefly, the tuberculum sellae, lowest point of the sphenoid sinus, and the lowest point of the sellar floor and three lines related to them were used to classify the sellar floor. This is being refer to as "three points and three line" method. RESULTS: Based on its location in the sphenoid sinus, the sellar floor can be classified into four types: 12 (8.3%) patients with high sellar, 70 (48.6%) with medium sellar, 30 (20.8%) with low sellar, and 32 (22.8%) with steep sellar. The maximum tumor diameter, maximum sellar floor diameter, and the intercarotid distance were all significantly different between patients with different types of sellar floor (P<0.001). For all patients, quick intra-operative locating of the sellar floor opening was achieved. 104 (72.2%) patients had total tumor resection, 28(19.40%) had subtotal tumor resection, and four (2.8%) had partial tumor resection. 20 (13.9%) patients experienced cerebrospinal fluid (CSF) leak, and there was no significant difference in CSF leak rate between groups. CONCLUSIONS: Pre-surgical classification and locating of the sellar floor is critical for understanding and assessing the transsphenoidal approach. Different types of sellar floor appeared in the surgery with different morphological features, the "three points and three lines" method helps the surgeon to pre-determine location of sellar floor opening and to shorten surgical time.