Regional anatomy of the diaphragmatic foramen and its clinical significance

Objective To perform an anatomical study of the structures around the diaphragmatic foramen and analyze the mechanism of cerebrospinal fluid leak and empty sella(ES).Methods With HE and Masson staining,the structures around the diaphragmatic foramen were observed microscopically on serial histological sections of 8 fetal specimens.The transsphenoidal approach was then simulated in 10 adult cadaver heads,and the structures around the diaphragnmatic foramen were observed under an operating microscope.Results The suprasellar arachnoid adhered tightly to the pia mater covering the upper part of the pituitary stalk,and folded into the sella through the diaphragmatic foramen.On the upper surface of the pituitary gland,the diaphragm adhered to the pia mater of the gland around the foramen,and their histological boundaries could not be distinctly identified on the serial sections.The suprasellar cistern terminated above the foramen due to the restriction by the arachnoid,pia mater and sellae diaphragma.Conclusion The close anatomic relationship between the sellae diaphragm,pia mater,and suprasellar arachnoid is critical to prevention of cerebrospinal fluid leak,and the breach of this anatomic relation,especially in the transsphenoidal approach for pituitary adenoma management that causes excessive traction of the tumor,results in separation or rupture of the arachnoid and pia mater,which can be an important factor contributing to cerebrospinal fluid leak.The separation of the sellae diaphragm,pia mater and the upper surface of the pituitary gland may also play an important role in the occurrence of ES. Key words: Neuroanatomy; Diaphragmatic foramen; Membranous structures; Cerebrospinal fluid leak; Empty sella