Current Concept of Vascular Structures of Spinal Arteriovenous Lesions

Understanding of current concepts of spinal arteriovenous lesions strictly depends on understanding of spatial vascular anatomy and visualization of focal vascular structures. Most classifications up to date are based on either topical localization of fistula or arteries that form arteriovenous shunt. Regardless of the implied classification, the major point of discrimination of the pathology is the possibility to treat it weighted against certain possibility to cause neurological symptoms. Hence, understanding of angiographic findings is the most crucial skill that neurovascular specialist should develop. Multiple classification systems are proposed nowadays, but the so-called “combined effort” system is the most widely used one. According to this classification, all spinal AV lesions are divided into the following subgroups: type I, radicular arteriovenous fistulas; type II, glomus AVMs; type III, juvenile AVMs; type IV, perimedullary pial fistulas; and type V, extradural shunts. Type V comprise of heterogeneous group that is slightly out of the scope of this chapter. While established classification system somewhat lacks in risk stratification and decision-making, it is the best tool in the development of understanding of complex pathological anatomy. Despite rapid development of noninvasive imaging techniques, catheter spinal angiography is still the gold standard of spinal vascular lesion visualization. Thus, the most important skill that neurovascular specialist is ought to have is the ability to “read” spinal angiogram, to differentiate normal structures from pathology. This ability comes with a lot of diligence, as spinal angiography is more tricky and tedious than cerebral DSA. Experience in open spinal surgery is also a valuable asset.