Angioarchitecture predicting hemorrhage in cerebral arteriovenous malformations

To find out lesions responsible for hemorrhage in arteriovenous malformations (AVMs), a retrospective study of angioarchitecture around the nidus was conducted in 27 patients who underwent conservative treatment. Comparison of angiograms revealed disappearance of an intranidal aneurysmal dilatation after the hemorrhagic events in two cases. The hematomas were adjacent to the dilatation, and no subarachnoid hemorrhage was evident. Obstruction of venous drainage, noticed in a case of spontaneous regression of AVM, was not demonstrated in the cases of hemorrhage. The intranidal aneurysmal dilatation is likely to have caused the hemorrhage in our cases. Careful endovascular embolization using proper materials should be indicated for an intranidal aneurysmal dilatation to prevent subsequent hemorrhage.