Anatomical variations in posterior part of the circle of Willis and their associations with brain infarct in different vascular territories

Abstract Background The relationship between anatomical variations in circle of Willis and brain infarction is controversial. The purpose of this study was to evaluate the relationship between anatomical variations in posterior portion of the circle of Willis assessed by MR angiography (MRA) and ischemic infarction in different brain territories. Methods This cross-sectional study was conducted on consecutive patients who underwent brain MRI and MRA for suspected cerebrovascular accident. The frequency of anatomical variations including persistent fetal origin of posterior cerebral artery (fPCA) and hypoplastic/aplastic posterior communicating artery (PCoA) and their association with infarction in different intracranial vascular territories was assessed. Results In total, 298 patients (155 male/143 female with mean age ± SD of 57 ± 15) were enrolled in the study and categorized into two groups with infarction (n = 142) and without infarction (n = 156). Sixty-three patients (21/1%) had fPCA and 231 (77.5%) had PCoA hypoplasia/aplasia. No significant correlation was identified between fPCA or PCoA hypoplasia/aplasia and presence of infarction. However, regarding the territories involved by infarction, the frequency of thalamus infarction was higher in subgroup with PCoA hypoplasia/aplasia, 17/101 (16.8%) compared to 1/41(2.4%) in the subgroup without ipsilateral PCoA hypoplasia/aplasia (p = 0.024). In two subgroups with and without ipsilateral fPCA variation, frequency of infarction in brain territories was not different significantly. Conclusions In patients with brain infarction, aplastic/hypoplastic ipsilateral PCoA is associated with higher incidence of thalamic territory infarction.