Circle of Willis Variants: Fetal PCA

Abstract

We sought to determine the prevalence of fetal posterior cerebral artery (fPCA) and if fPCA was associated with specific stroke etiology and vessel territory affected. This paper is a retrospective review of prospectively identified patients with acute ischemic stroke from July 2008 to December 2010. We defined complete fPCA as absence of a P1 segment linking the basilar with the PCA and partial fPCA as small segment linking the basilar with the PCA. Patients without intracranial vascular imaging were excluded. We compared patients with complete fPCA, partial fPCA, and without fPCA in terms of demographics, stroke severity, distribution, and etiology and factored in whether the stroke was ipsilateral to the fPCA. Of the 536 included patients, 9.5% (n = 51) had complete fPCA and 15.1% (n = 81) had partial fPCA. Patients with complete fPCA were older and more often female than partial fPCA and no fPCA patients, and significant variation in TOAST classification was detected across groups (P = 0.023). Patients with complete fPCA had less small vessel and more large vessel strokes than patients with no fPCA and partial fPCA. Fetal PCA may predispose to stroke mechanism, but is not associated with vascular distribution, stroke severity, or early outcome.

Figure 1

MRI TOF demonstrating a complete fetal PCA (cfPCA) and partial fetal PCA (pfPCA). (a) Typical pattern of PCAs as terminus of basilar artery. (b) Partial fPCA on the right side. The arrow shows an atretic communication between the basilar artery and the posterior communicating artery forming the PCA. (c) Complete fPCA on the left side. The arrow shows lack of communication between the basilar artery and the PCA.