Abstract Background and aims The fetal type posterior cerebral artery (FTP) is the most common embryologically derived Circle of Willis (CoW) variation, holding a prevalence of up to 46% in the general population. It is defined as an aplasia or hypoplasia of the pre-communicating segment of the posterior cerebral artery. Currently, CoW variations are overlooked due to suspected clinically insignificance. However, combined with the increasing trend of cerebrovascular disease, the FTP can have significant outcomes. This literature review aims to evaluate the effects of this variation on ischaemic strokes and intracranial arterial aneurysms. Methods A comprehensive review of literature surrounding the FTP was undertaken. Google Scholar, Medline, and PubMed databases were searched. 104 papers whose abstracts mentioned the ‘fetal posterior cerebral artery’ were read and results were extracted. Results This variation significantly reduces collateral circulation in the brain which increases the incidence of ischaemic stokes and leads to worse clinical outcomes. Stroke aetiology can too be altered leading to changes in the typical treatment. FTP presence can also increase the formation, rupture, and recurrence rate of intracranial arterial aneurysms leading to haemorrhagic strokes. Conclusions This study demonstrates the clinical significance of the FTP and can be used to improve clinicians understanding of the importance of CoW variations. Large-scale studies are required to encourage revisions to cerebral pathology treatment pathways. Conflict of interest Dr Chloe Thomas: nothing to disclose
Chloe Thomas (Fri,) studied this question.