Translated Abstract
Background：The operational technique of endoscopic third ventriculostomy (ETV) had made considerable great improvements over the last few years, of which indications were continuously widened. It was played an more and more important role in treatment of obstructive hydrocephalus. However the floor of third ventricle where ETV was carried out is in the very deep location of hemicerebrum, between two diencephalons and is close to important nerves and blood vessles such as hypothalamus and Willis circle The pathway which passed neuroendoscope is long in operation. So in order to lessen the trauma to peripheral structure and make better use of the technique, we should familiar with important anatomical structure in ETV and avoid to hurt important structure ,which would be applied to the objective index for the clinical ETV.Objective To study the neuroendoscopic anatomic features of lateral ventricle、third ventricle and interpeduncular cistern and discuss the technique of endoscopic third ventriculostomy via cortex-ventricle approach. To offer anatomical applied basis for the clinical endoscopic operation in ventricle and interpeduncular cistern. 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 distance of important structure was measured.Results：① The important anatomic road marks in ETV are as follows: choroid plexus，thalamostriata vein、septal vein、interventricular foramen、mamillary body、infundibular recess and dorsum sellae. ② When the neuroendoscope was inserted into the lateral ventricle ，the overall frontal angle、overall caudomedial part and partial occipital angle could be observed clearly. The medial wall of the frontal angle and caudomedial part is composed of the septum pellucidum. On the surface of it there are several veins to gather towards posterior of the interventricular foramen. The choroid plexus is located on the floor of the lateral ventricle and gather forward into the interventricular foramen. The thalamostriata vein lies on the surface of the thalamostriate sulcus and goes forward into internal cerebral veins. ③ On the floor of the third ventricle, the optic chiasma infundibulum recess, mammilary body and the aqueduct can be seen in order. It is very thin where is between infundibular recess and mamillary body in the floor of the third ventricle, which is the area of ETV .The length of this area is 5.5±0.9（3.5~7.6）mm. ④ Liliequist membrane covers the roof of the interpeduncular cistern . The anterior wall of cistern is composed of the dorsum sellae and clivus. The posterior wall of the cistern is composed of ventral brain stem. Basilar artery lies on the surface of the basilar sulcus which be on the ventral brain stem. Extremity branch of basilar artery comprises the posterior cerebral artery and superior cerebellar artery. On the lateral wall of the cistern there are the posterior communicating artery and oculomotor nerve which go forward into the middle cranial fossa in approximation parallel.Conclusion：① ETV coincide with physiological cerebrospinal fluid circulation, its operation is simple without embedded extraneous material. So ETV is the first choice for the management of obstructive hydrocephalus now. ② Neuroendoscope through the cortex-ventricle is an ideal approach to third ventriculostomy. ③ It is the natural anatomic gap between cerebral ventricle and basal cistern that provides enough operational space for ETV. Neuroendoscope can provide clear visual field、less trauma and better operational outcome. ④ Familiaring with the road marks of operation passway and related anatomical data help to reach the floor of third ventricle and guarantee the accuracy and security of operation.
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