ABSTRACT
Normal anatomic variants encountered in the course of treatment are often identified as incidental findings. However, depending on the pathology, these variants may portend an increased treatment risk or, at worst, may lead to disastrous consequences. These variants are ubiquitous and can occur at any location in the vascular system. Furthermore, although not variants in the anatomical sense, the changes associated with aging can often make it challenging to access and treat cerebrovascular pathology. Detailed analysis of preoperative vascular imaging with either computerized tomographic angiography or magnetic resonance angiography is crucial to the identification of these variants and formulation of a successful management strategy. This chapter is therefore organized by vascular segments, from proximal to distal, and briefly describes the pertinent normal anatomy, true anatomical variants, and “acquired variants” (i.e., effects of aging and vascular disease). Recognition of these variants is the most important first step in their management. Where applicable, management techniques for these variants conclude each section.
