[Surgical and pathological study of the approach to the superior choroid plexus of the 3 rd ventricle. One case of posterior choroid arteriovenous aneurysm (author's transl)].

The authors describe a case of an arterio venous malformation of the tela choroidea of the third ventricle which was feeding by the postero medial choroidal artery and draining by the internal cerebral vein. This A-V malformation was microsurgically excluded in sitting position by an occipital interhemispheric, transtentorial and transversal transcallosal approach without any postsurgical clinical signs. An anatomical study of this region shows an easy recognition of the choroidal postero medial artery by the regular presence of an arterial loop which concavity is crossed by the terminal segment of the basilar vein of Rosenthal. The knowledge of the occipital internal veins drained in the callosal posterior vein to form a common trunk, the cuneo limbic vein drained itself into the vein of Galen is important to know. This venous system is to preserve at the time of retraction of the occipital lobe to not give rise to infarction and therefore hemianopsia. At least the transverse section of the posterior part of corpus callosum permits a good approach of the roof of the third ventricle and is clinically very harmless if the protection of the cuneo limbic vein is assumed.