Is a fetal origin of the posterior cerebral artery a risk factor for TIA or ischemic stroke? A study with 16-multidetector-row CT angiography.

BACKGROUND AND PURPOSE: Fetal origin of the posterior cerebral artery (PCA) is not uncommon. Whether patients with this anomaly have a higher risk of ischemic stroke in the territory of the PCA is not known. The clinical benefit of screening for a fetal origin in patients with TIA or stroke in the territory of the PCA and an ipsilateral atherosclerotic carotid stenosis is not clear. This study assessed the frequency of a fetal origin of the PCA in patients with a TIA or infarct in the territory of the PCA with 16-multidetector-row CT angiography (CTA).

METHODS: 82 patients (52 male; mean age = 64; range 19 to 90 years) with isolated homonymous hemianopia and/or a PCA infarct underwent CTA of the carotid artery and circle of Willis.

RESULTS: A fetal origin of the PCA at the symptomatic side was present in 14 patients (17 %) and at the asymptomatic side in 18 patients (22%) (OR: 0.7; 95 % CI: 0.3 to 1.7). Severity of stenosis (NASCET criteria) of the ICA at the symptomatic side was < 30%, 30-49% and > or = 50% in 72, 2 and 8 patients, respectively. Number and frequency of a fetal origin in these groups were 12 (17 %), 0 (0%) and 2 (25 %), respectively. There was no association between a severe carotid stenosis and a fetal origin of the PCA at the symptomatic side.

CONCLUSION: This study does not provide arguments for an increased risk of ischemic stroke in the territory of the PCA in patients with a fetal origin of the PCA. A few patients with a TIA or infarct in the territory of the PCA have a fetal origin of the PCA in combination with a high-grade stenosis of the ipsilateral ICA, but not more often than one would expect from chance. Nevertheless, these patients may benefit from carotid endarterectomy.