Morphological Variations of the Vertebral Artery: Clinical Implications

The vertebrobasilar system is associated with morphological variations such as hypoplasia, duplication, tortuosity, fenestration, asymmetry of the vessels, and a variable posterior inferior cerebellar artery (PICA) origin. Deviation from typical morphologic configuration can predispose or aggravate the development of cerebrovascular diseases such as vertebrobasilar insufficiency, posterior circulation stroke, and aneurysms. In addition, morphologic variations can predispose the arterial system to iatrogenic injuries during endovascular or surgical intervention. This chapter examined the anatomical features of the extracranial (V1–V3) and intracranial (V4) components of the vertebral artery (VA), highlighting the clinical management of pathologies associated with anatomical variations. Using computed tomography and digital subtraction angiography images, we illustrated five clinical cases of VA morphologic variations and associated pathologies. For each type of variation, we describe the clinical management of associated pathologies. Due to the unpredictable characteristics of vascular variations, this information will contribute significantly to the management of VA pathology associated with variation and help in decision-making for surgical intervention around each segment of the VA and the principal branch, PICA.