Vein of Galen ligation in the primate

✓ The vein of Galen was ligated in 16 Rhesus monkeys and six mongrel dogs, and the animals followed for periods up to six months. Ventricular size was determined preoperatively by pneumoencephalography. Angiography was performed prior to surgery and at intervals from the immediate postoperative period to 6 months following vein ligation. After sacrifice, all brains were serially sectioned and examined by light microscopy. In no case was hydrocephalus found to follow vein of Galen ligation. Consequences were limited to angiographic dilatation of major draining sinuses and cortical veins and microscopic dilatation of diencephalic and choroidal vessels. These changes were evident in the immediate postoperative period and persisted for as long as the animals were followed.