Cerebral aneurysms associated with arteriovenous malformation (AVM) have often been reported with special reference to the hemodynamic effect of aneurysm formation. In this paper, we surveyed 15 cases with such combinations and discussed the etiologic aspects and suitable therapeutic plans.
The mean age of our patients was older than that of patients with AVM's alone. This suggests that the duration of the hemodynamic effect was important in the formation of aneurysms associated with AVM's. Seventy-two percent of the aneurysms were located on the arteries hemodynamically related to the AVM. When the size of the nidus was larger, aneurysms tended to be located more peripherally on the feeding arteries close to the nidus.
Though both AVM's and aneurysms cause hemorrhagic cerebrovascular diseases, their natural histories differ, especially in the rate and timing of rebleeding. It is important to determine which lesion is responsible for the bleeding. When there is subarachnoid hemorrhage (SAH) but no intracerebral (ICH) or intraventricular hemorrhage (IVH) are shown on the CT scan, the bleeding source will be a ruptured aneurysm. On the other hand, ICH or IVH with or without SAH is mainly due to AVM rupture.
In treatment of cases where aneurysms are associated with an AVM, both lesions should be operated on simultaneously, and if this is impossible, the responsible lesion should be operated on first. In cases with aneurysm rupture, considering its high risk of rebleeding in the acute stage, the aneurysm should be clipped as soon as possible. Even if the aneurysm is not ruptured but is located on an artery where aneurysms usually develop, such aneurysms should also be operated on because of the high risk of bleeding.
