Arteriovenous malformation of the vein of Galen.

Vein of Galen aneurysm may be caused by a spectrum of abnormal arteriovenous connections ranging from extensive malformations involving the tentorial dura and upper brain stem vessels to the rarer condition of a simple end to end fistulous connection. The diagnosis of the latter condition of a simple arteriovenous fistula is important because it may be effectively managed by surgical interruption of the feeding fistulous vessels. Two cases with the direct fistulous connections are presented.