[Histopathology of the vein of Galen].

Histology of cerebral arteries and veins are reviewed to show variances with extracerebral blood vessels. Muscles fibers even in large cerebral veins are easily overlooked. The thick wall of the vein of Galen grossly and microscopically resembled dura mater fed by microscopic blood vessels and capillaries. The authors reported 4 cases of arteriovenous aneurysms of the great vein of Galen. When compared to the rest of the histological reports on this subject published till now, it is obvious that this new cases bring new facts. First is the presence of an irregular muscle coat in the aneurysmal wall suggesting early hemodynamic troubles. The second and most important data is the association of multiple malformations of the pineal gland, of the vascular elements of the tela choroidea of the third ventricle between which the aneurysm of the great cerebral vein is found. These unusual data suggested complex congenital malformation in the early stages of development.