Twelve cases of intracranial aneurysm associated with cerebral arteriovenous malformation were found in a total of 130 cases of cerebral AVM (9.2%). Hemorrhages, including intracerebral hematoma, were found in 10 cases. The source of bleeding was presumed to be the AVM in five cases and the aneurysm in three cases. Convulsion occurred in two cases. The aneurysm was situated in the main feeding artery to the AVM in five cases, proximal to the origin of the main feeding artery in nine and unrelated to the AVM in two. These findings strongly indicate the importance of hemodynamic stress in aneurysm formation.
Aneurysms and associated AVMs should both be treated surgically, preferably in one operative stage. The aneurysm should be treated first, if it is the source of hemorrhage. It should be treated first, if it lies proximally to the AVM, even if the source of hemorrhage is unclear or the source is the AVM. The AVM should be removed in advance of the aneurysm only when each lesion is situated in a different arterial region and the AVM is the source of hemorrhage.
