Radiological topography and classification of angioma-like arterial networks in cerebro-vascular collateral circulation.

The radiological appearance and localization of collateral cerebrovascular networks are described. The development and distribution of these arterial networks is due to the site of internal carotid artery stenoses. Including interposed arterial nets, the following types are classified: (1) basal arterial networks near the carotid siphon; (2) arterial networks in the region of the basal ganglia (Moyamoya syndrome); (3) ethmoid arterial networks; (4) arterial networks on the cerebral convexity representing transdural external-internal carotid anastomoses, and (5) circumscribed arterial networks interposed in the course of a major cerebral vessel. The differential diagnostic criteria and aetiological factors of these anastomotic intracranial networks are discussed.