Neuroendoscopic anatomy of third ventriculostomy

Objective To study the neuroendoscopic anatomic features of lateral ventricle, third ventricle and interpeduncular cistern so as to offer an applied anatomical basis for the clinical endoscopic third ventriculostomy via the anterior cortex-ventricle approach.Methods The third ventriculostomy was operated on 15 adult embalmed cadaveric heads,using neuroendoscope via the cortex-ventricle approach.We observed the important anatomic features and adjoining relationship in the lateral ventricle,third ventricle and interpeduncular cistern.The distances of important structures were measured.Results In the lateral ventricle,the overall frontal angle,overall caudomedial part and partial occipital angle could be observed clearly.On the floor of the third ventricle,optic chiasma, infundibular recess,tuber cinereum,mammillary body and aqueduct could be seen in order from anterior to posterior.The shape ofinterpeduncular cistern was inverse circular cone.Liliequist membrane covered the roof of the interpeduncular cistern.Basilar artery lied on the surface of the basilar sulcus which was on the posterior wall of the cistern.Extremity branches ofbasilar artery comprised the posterior cerebral artery and the superior cerebellar artery.On the lateral wall of the cistern,there were the posterior communicating artery and oculomotor nerve which went forward into the middle cranial fossa in almost parallel.Conclusion There is a natural anatomic gap between cerebral ventricle and basal cistern that provides enough operational space for endoscopic third ventriculostomy.Being familiar with the road marks of operation approach and the related anatomical data help to reach the floor of third ventricle and guarantee the accuracy and security of operation.