Classification of vascular malformations of the central nervous system.

The ability to systematically and meaningfully classify a disease is in many ways a reflection of our overall understanding of it. Over time, nosologic schemes applied to any disease typically undergo a characteristic evolution from purely descriptive, to pathoanatomic and/or embryologic, to finally biological definitions. With the recent developments in further elucidating the pathophysiology, histopathology, natural history, and cellular biology of various vascular malformations occurring within the central nervous system, it is time to derive a more comprehensive and "universal" classification system that integrates classic pathoanatomic schemes with a biologically defined scheme previously developed for systematic vascular malformations. Such a system is proposed and discussed, including detailed review of important subtypes.