Is foetal variant of posterior cerebral artery a risk factor for ischemic stroke?

Context: Posterior cerebral artery (PCA) derives its blood supply from the vertebrobasilar system. However, in 10% of the population, they get blood supply from the internal carotid artery via a posterior communicating artery. This variant is called as fetal type of PCA (fPCA). Whether fPCA is an anatomical variant or a predisposing factor for a cerebrovascular event remains an enigma. Aims: The aim is to assess if fPCA is associated with increased risk of ischaemic stroke or other vascular anomalies. Settings and Design: It is a retrospective cross-sectional observational study. Subjects and Methods: Patients who underwent MR or CT angiography, over 5 years for various neurological illnesses were screened for fPCA. Those patients were assessed for vascular anomalies and ischaemic stroke. Statistical Analysis Used: Chi-square in the Statistical Package for the Social Sciences v23. Results: On analysis of 250 patients, five had aneurysms; three had AV malformation, one with Fenestration and one with vascular loop. And 51% were found to have an ischaemic stroke, in which 34% had large vessel disease, 41% had lacunar infarct, 7% had a cardioembolic stroke and 18% had an embolic stroke of unknown source with predominantly middle cerebral artery territory infarct (55%). Among 127 patients with ischaemic stroke, 45% had infarcts ipsilateral to fPCA vs 28% on the opposite side of fPCA. Conclusions: We conclude that patients with fPCA had increased risk of MCA infarct probably due to poor collaterals from posterior circulation and fPCA is not associated with increased risk of aneurysms or AV malformations.