Microsurgical anatomy of the diaphragma sellae and its role in directing the pattern of growth of pituitary adenomas

OBJECTIVE: To evaluate the anatomic aspects of the diaphragma sellae and its potential role in directing the growth of a pituitary adenoma. METHODS: Twenty cadaveric heads were dissected and measurements were taken at the level of the diaphragma sellae. RESULTS: The diaphragma sellae is composed of two layers of dura mater. There is a remarkable variation in the morphology of the diaphragm opening. The average anteroposterior distance of the opening was 7.26 mm (range, 3.4-10.7 mm) and the average lateral-to-lateral distance was 7.33 mm (range, 2.8-14.1 mm). CONCLUSION: The variability in the diameter of the opening of the diaphragma sellae could explain the growth of pituitary tumors toward the cavernous sinus or toward the suprasellar region.