Extended endoscopic endonasal approach to the suprasellar parachiasmatic cisterns: anatomic study

The objective of this study is to recognize the available endoscopic routes during approaches to the suprasellar region and the surgical endoscopic anatomy of the related neurovascular structures. Extended endoscopic endonasal approach to the suprasellar region (EEASR) through the planum sphenoidale was performed in five fresh adult cadavers. The anatomic characteristics of the suprasellar parachiasmatic cisterns were studied and documented following the resection of the planum sphenoidale and opening the dura to expose the anterior incisural space. Two separate surgical corridors could be used during EEASR: one above and the other below the chiasm. The suprachiasmatic route exposed the gyrus recti, interhemispheric fissure, anterior cerebral artery complex, the lamina terminalis, and through this structure the anterior recess of the third ventricle. The subchiasmatic route exposed the pituitary stalk, superior hypophyseal artery, supraclinoidal internal carotid artery, origin of the ophthalmic artery, anterior choroidal artery, posterior communicating artery, uncus, optic tract, basilar artery and its bifurcation, pons, posterior cerebral artery, superior cerebellar artery, and oculomotor nerve. The EEASR, a minimally invasive route to suprasellar parachiasmatic area, provided wide exposure of the basal cisterns. The surgical areas that were accessed through the subchiasmatic corridor could be divided into a medial part that included the interpeduncular and prepontine cisterns and a lateral part that contained carotid and sylvian cisterns superiorly and the crural and ambient cisterns inferiorly.