Impact of posterior communicating artery on basilar artery steno-occlusive disease

Background: Acute brainstem infarction with basilar artery ( BA) occlusive disease is the most fatal type of all ischaemic strokes. This report investigates the prognostic impact of the posterior communicating artery (PcoA) and whether its anatomy is a safeguard or not. Methods: Consecutive patients who had acute brainstem infarction with at least 50% stenosis of BA upon CT angiography (CTA) were studied. The configuration of PcoA was divided into two groups upon CTA: "textbook'' group (invisible PcoA with good P1 and P2 segment) and "fetal-variant of PcoA'' group (only visible PcoA with absent P1 segment). Baseline demographics, radiological findings and stroke mechanisms were analysed. A multiple regression analysis was performed to predict clinical outcome at 30 days (modified Rankin disability Scale (mRS <= 2)). Results: Among all 95 patients, 58% (n=55) had good prognoses (mRS <= 2). Interestingly, 44 patients (46.3%) had at least one fetal-variant PcoA (26 bilateral, 18 unilateral). By multiple logistic regression analysis, the atherosclerotic mechanism (OR 18.0; 95% CI 3.0 to 107.0) and presence of fetal- variant PcoA (OR 5.1; 95% CI 1.4 to 18.8) were independent predictors for good prognosis and initial NIH stroke scale score (OR 1.24 per one-point increase; 95% CI 1.1 to 1.4) for poor prognosis. Conclusions: Fetal-variant PcoA appears to act as a safeguard against ischaemic insult in acute stroke victims involving the brainstem with BA occlusive disease. This result can be explained by the fact that patients with fetal- variant PcoA have a smaller area of posterior circulation and a possibility of retrograde filling into the upper brainstem through the fetal- variant PcoA.