Diaphragma sellae orifice ratio, is it an applicable anatomical index to determine the direction of the growth of pituitary macroadenomas?

Abstract

ObjectiveThis study aimed to assess the morphology of the diaphragma sellae, its orifice, and calculation of an anatomical index: the diaphragma sellae orifice surface area to the diaphragma sellae surface area ratio (SAO/SAD) as a hypothetical measure that may affect the direction of the growth of pituitary macroadenomas. Methods:In this anatomical study, fresh cadavers (age > 26 years) with intact skull base, in whom craniotomy was mandatory for identifying the reason of their death were included. After craniotomy, a photograph at the level of the diaphragma sellae was taken, and anatomical landmarks of the diaphragma sellae and its orifice were measured by Osiris software (Version 2.2; Digital Imaging Unit, University Hospital of Geneva, Switzerland). Descriptive statistics were expressed for anatomical parameters using the Statistical Package for the Social Sciences (SPSS, Version 11.5. Chicago, SPSS Inc.). ResultsOf the 210 cadavers, 153 met the inclusion criteria (130 males, 23 females) and were dissected. The average anteroposterior diameter of the orifice was 4.75 ± 1.92 mm, the average lateral-to-lateral diameter was 5.26 ± 2.33 mm, and the average surface area of the orifice was 20.82 ± 15.70 mm2. The average anteroposterior diameter of the diaphragma was 8.26 ± 1.59 mm, the average lateral-to-lateral diameter was 11.07 ± 2.65 mm, and the average area of diaphragma sellae was 72.11 ± 23.54 mm2. Findings were categorized into four groups according to the SAO/SAD, and group A with the ratio of (SAO/SAD ≤ 0.25) was the most frequent ratio comprising 56% of the specimens. ConclusionDiaphragma sellae with small openings was the most frequent type of diaphragma sellae. Among a wide range of factors affecting the direction of adenoma transgression, diaphragma sellae with small openings (SAO/SAD ratio ≤ 0.25) might have a contributing role on the deviation of the pituitary macroadenomas caudally and laterally; however, this is a hypothesis based on anatomical measurements of subjects who did not harbor pituitary adenoma, hence further complementary evaluations are necessary to assess the validity and applicability of this anatomical index.