The pathology of arteriovenous malformations of the brain treated by embolotherapy. II. Results of embolization with multiple agents.

Light microscopic and immunohistochemical examination was undertaken of intracranial arteriovenous malformations (AVMs) surgically resected from 18 patients, each of whom had undergone preoperative angiographic embolization with multiple agents. Distinct patterns of tissue reaction to these agents were noted, even when more than one substance was present in a vascular lumen. Avitene produced the mildest tissue response but resulted in relatively early endothelialization and recanalization. Cyanoacrylates were longer-lasting but associated with more acute and chronic (including granulomatous) inflammation and vessel wall changes. Polyvinyl alcohol foam/ethanol mixture had intermediate properties. Endothelial proliferation over embolization material was confirmed using immunohistochemical application of an antibody to cell proliferation-specific proteins. The significance of these findings for combined endovascular and surgical treatment of cerebral vascular malformations is discussed.