A Morphometric Study of the Foramen of Diaphragma Sellae and Delineation of Its Relation to Optic Neural Pathways through Computer Aided Superimposition

Abstract

The diaphragma sellae (DS) is a fold of dura that forms a partial roof over the pituitary gland. The foramen of the diaphragma sellae (FDS) is thereby a pathway for suprasellar extension of pituitary tumors. The purpose of this study was to describe the anatomical dimensions of the DS and FDS and to understand the relationship of FDS with the overlying optic chiasma. The study was conducted in 100 autopsy cases. Measurements were taken using vernier calipers. Photographs, taken before and after removal of optic pathway, were superimposed using image processing software. The results showed that the mean A-P dimension of DS was 1.17 ± 0.48 cm; the lateral dimension of DS was 1.58 ± 0.60 cm. The mean A-P dimension of FDS was 0.66 ± 0.42 cm; the lateral dimension of FDS was 0.82 cm ± 0.54 cm. The shapes of FDS were irregular (40%), transversely oval (29%), circular (13%), sagittally oval (11%), or trapezoid with posterior dimension more than the anterior one (6%) or anterior dimension more than the posterior one (1%). The margins of FDS were either well defined (31%) or ill defined (69%). The positional relation of FDS to optic chiasma was also found out.

Predicting Arachnoid Membrane Descent in the Chiasmatic Cistern in the Treatment of Pituitary Macroadenoma

“…The average area of the medial opening was 147.9 mm 2 (range, 6.8 to 397.5 mm 2 ); this was substantially larger than the normal opening, which was estimated to be between 34.2 and 82.8 mm 2 (calculated from the reported range of average maximal diameter between 6.6 and 8.2 mm and the assumption that the morphology was oval). The mean area of the DS, which was previously reported to be between 130.4 to 184.9 mm 2 in the literature [ 2 , 9 , 17 ], also clearly increased and was 336.7 mm 2 on average in this study. These increases were significantly correlated with arachnoid membrane descent through the medial opening after removal of the pituitary tumor.…”

“…In the center, there is an opening that allows the pituitary stalk to pass from the hypothalamus to the posterior pituitary gland. This opening has been attributed varying terminology, including medial opening [ 2 ], central opening [ 7 , 8 ], foramen of DS [ 17 ], and diaphragm opening [ 14 , 15 ]. Previous anatomical studies of the medial opening reported that the average maximal diameter of the medial opening was between 6.6 and 8.2 mm [ 2 , 8 , 17 ], and most are located in the posterior middle portion of the DS [ 2 , 8 ].…”

“…This opening has been attributed varying terminology, including medial opening [ 2 ], central opening [ 7 , 8 ], foramen of DS [ 17 ], and diaphragm opening [ 14 , 15 ]. Previous anatomical studies of the medial opening reported that the average maximal diameter of the medial opening was between 6.6 and 8.2 mm [ 2 , 8 , 17 ], and most are located in the posterior middle portion of the DS [ 2 , 8 ]. As a pituitary adenoma grows to fill the sella turcica, the likely space into which the adenoma further expands would be the chiasmatic cistern through the medial opening of the DS or cavernous sinus via the medial wall of the cavernous sinus because there are sturdy barriers composed of bony structures on the anterior, inferior, and posterior surfaces of the sella turcica.…”

The Five Diaphragms in Osteopathic Manipulative Medicine: Myofascial Relationships, Part 2

“…Its coating is dural and bilaminar (in adults) [13]. The diaphragma sellae derives from the dural continuation of the tentorium cerebelli; the optic chiasm passes over the diaphragma sellae, sharing dural fibers ( Figure 1) [14]. There is a close dural relationship between the tentorium cerebelli and the optic nerve.…”

“…There is a close dural relationship between the tentorium cerebelli and the optic nerve. Images reproduced with permission of Dr. Doris George Yohannan [14].…”