Recurrent stroke in patients with symptomatic carotid artery occlusion is associated with high-volume flow to the brain and increased collateral circulation

Background and Purpose-To investigate whether the risk of recurrent ipsilateral ischemic stroke in patients with symptomatic carotid artery occlusion (CAO) is related to (1) volume flow in the contralateral internal carotid artery (ICA), basilar artery ( BA), and middle cerebral arteries (MCAs), and ( 2) intracranial collateral flow to the symptomatic side, measured in the first 6 months after the qualifying symptoms occurred. Methods-We prospectively studied 112 patients with symptomatic CAO. Quantitative volume flow was measured with magnetic resonance angiography (MRA) and collateral flow via the circle of Willis with MRA, via the ophthalmic artery (OA) with transcranial Doppler sonography, and via leptomeningeal anastomoses with conventional angiography. Results-During 49 +/- 14 months of follow-up (mean +/- SD), 7 patients had recurrent ipsilateral ischemic stroke. Compared with patients without recurrent stroke, these patients had significantly higher total flow to the brain, ie, ICA + BA flow (mean 536 mL/min versus 410 mL/min; P < 0.05), and significantly higher contralateral ICA flow (355 mL/min versus 209 mL/min; P < 0.001), whereas BA and MCA flow showed no significant differences. Also, they more often had Willisian collateral flow (P < 0.05), mainly caused by increased collateral flow via the posterior communicating artery (PCoA; 71% versus 28%; P < 0.05), whereas collateral flow via the OA and leptomeningeal anastomoses did not differ significantly. Conclusions-Recurrent ipsilateral ischemic stroke in patients with symptomatic CAO is associated with high volume flow to the brain and increased collateral PCoA flow.