Anatomical variations of the posterior circulation: case reports and a review of literature.

INTRODUCTION The intracranial vascular anatomical variations, although rare, represent a interesting field of research, since many anomalous variants are possible and in most cases they remain asymptomatic. The capability of the cerebral circulation to adapt to several flow changes is confirmed by the fact that in several cases these anatomical variation compensate for an eventual unsuccessful development of the normal circulation, expecially in the posterior section of cerebral circulation. MATERIALS AND METHODS A comprehensive review of PubMed literature was performed and three clinical cases have been analyzed. RESULTS Several angiographic and MR-angiography reports have been evaluated, regarding general and specific anatomical variants of the posterior circulation. DISCUSSION Although rare, the anatomical variations of the posterior intracranial circulation represent an interesting field of investigation in order to achieve a better comprehension of the embryological development of the circulatory system.