Posterior communicating artery hypoplasia as a risk factor for acute ischemic stroke in the absence of carotid artery occlusion.

Posterior communicating artery (PCoA) hypoplasia is a fetal variant of the Circle of Willis. According to angiograms and autopsy reports, this congenital variation is found in 6-21% of the general population. PCoA hypoplasia only becomes a risk factor for ischemic stroke in the presence of ipsilateral internal carotid artery (ICA) occlusion. The aim of our study was to determine the role of PCoA hypoplasia in acute ischemic stroke in the absence of ICA occlusion. We examined 310 acute ischemic stroke patients (mean age+/-standard deviation; 68.9+/-15.6 years). Cerebral magnetic resonance angiography was performed within 72 hours of ischemic stroke onset. For comparison, a risk factor-matched control group was recruited. Conditional logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CI) to estimate the independent effect of potential risk factors. The overall incidence of PCoA hypoplasia in our experimental group was 19.35% (n=60), which was significantly higher than in the control group (8.20%, n=22, p=0.036, OR, 3.21; 95% CI, 1.43-9.62). The most common ischemic event was ipsilateral thalamic lacunar infarctions with or without occipital lobe involvement. Based on our results, PCoA hypoplasia appears to be a contributor to the risk of ischemic stroke, even in the absence of ICA occlusion. This risk is especially pronounced for strokes involving arteries that penetrate the thalamus.