Embolization is used as a radical therapy, as well as an adjunctive therapy with surgery for cerebral arteriovenous malformations (AVM). Eight patients underwent endovascular embolization and then surgical resection for cerebral AVM. In two cases, although AVM was embolized completely on the digital subtraction angiographical (DSA) evaluation, slight arterial blood filling into the nidus of AVM was observed on the surgical exploration. Postoperative computerized tomography (CT) demonstrated extent infarction area which was seemed secondary to occlusion of feeding arterial trunk due to retrograde thrombosis from nidus, although new neurological deficits were not recognized because of infarction in the non-dominant temporal lobe. In three cases, embolization of AVM was partial, because catheterization into the all feeding arteries was difficult. But, in two cases who had AVM in the right temporal and in the left occipital lobe respectively, surgical removal of AVM was performed completely without excessive hemorrhage. In another case who had AVM in the corpus callosum, although AVM was smoothly removed, the patient died of postoperative pulmonary embolism. In three cases, AVM could not be embolized at all because of impossible catheterization into feeding arteries. Histological findings of removed AVM which was completely embolized angiographically demonstrated that embolus mainly existed in the nidus and draining veins, and existence of blood around the embolus in these vessels.
These histological findings and the our intraoperative obseravation of slight arterial blood inflow into the nidus in the angiographically complete embolized AVMs imply that AVM should be removed surgically, even if it is embolized sufficiently. We must not forget that angiographical complete embolization of AVMs may provoke infarction of the normal brain around them, although they can be removed surgically without difficulty by the embolization.