Variation and Anomalies of the Posterior Cerebral Artery: Review and Pilot Study.

Variations and anomalies of the posterior cerebral artery (PCA) have several clinical implications, including assisting in understanding the clinical signs of a stroke. Anomalies have been described previously; however, few reports mention the origins, absence, duplication and triplication of the cortical branches. Furthermore, the PCA branching pattern has not been adequately described. The aim of this study was to describe the anatomy and anomalies of the PCA. Results of a pilot study were additionally included. The quantity, origin, diameter and length of the PCA cortical branches were described in this review, as well as the branching pattern and the anomalies. Accordingly, the pilot study reported on these aspects. In the pilot study it was evident that the description of the branching pattern is not the "normal" pattern, since it was only observed in one case. This pattern was re-evaluated and three groups were described; monofurcation, bifurcation and trifurcation. Furthermore, one case of a fenestration was observed. Aneurysms tend to form at branching points, thus knowledge of the branching pattern can aid in detection of ruptured and unruptured aneurysms in this region. This review outlined several gaps in the literature, and a pilot study was included to fill some of these gaps. Future research should especially focus on the branching pattern of the PCA. Possible sex, age and population differences may also exist.