Meningeal collateralization to normal cerebral vessels associated with intracerebral arteriovenous malformations: Functional angiographic considerations

External carotid arteries can provide collateral supply to anatomically normal brain tissue, made functionally ischemic by proximal vascular occlusion, or by fistulous shunting of blood through an arteriovenous malformation. The occlusion of such a meningeal collateral at angiography in a case of arteriovenous malformation demonstrated the delicate balances and rapid shifts in flow which may occur in such lesions. Selective injections of contrast materials into external carotid arteries are essential for the investigation of intracerebral arteriovenous malformations, particularly in patients undergoing evaluation for intravascular embolotherapy.