Growth of Flow-Related Aneurysms Following Occlusion of Cerebral Arteriovenous Malformation.

Background:  Flow-related aneurysms (FRAs) associated with cerebral arteriovenous malformations (AVMs) pose a significant therapeutic challenge. Both their natural history and management strategy are still unclear and underreported. FRAs generally increase the risk of brain hemorrhage. However, following AVM obliteration these vascular lesions are expected to disappear or remain stable.

Methods: We present two cases where growth of FRAs was detected following complete obliteration of an unruptured AVM.

Results:  The first patient presented with proximal middle cerebral artery (MCA) aneurysm growth after spontaneous and asymptomatic thrombosis of the AVM. In our second case, a very small aneurysmal-like dilation located at the basilar apex enlarged to a saccular aneurysm following complete endovascular and radiosurgical obliteration of the AVM.

Conclusion:  The natural history of flow-related aneurysms is unpredictable. In the cases where these lesions are not managed first, there should be close follow-up. When aneurysm growth is evident, active management strategy seems mandatory.