Collateral flow and ischemic brain lesions in patients with unilateral carotid artery occlusion

Objective: To investigate the association between ischemic brain lesions and intracranial collateral blood flow in patients with unilateral occlusion of the internal carotid artery (ICA). Methods: Sixty-eight consecutive patients were included. Ischemic lesions on MRI were identified on hard copies, and volume measurements of the lesions were performed on an MR workstation. Intracranial collateral pathways were studied with MR angiography, digital subtraction angiography, and transcranial Doppler sonography. Results: The presence of collateral flow via the anterior communicating artery (ACoA) was associated with a reduction in prevalence (p = 0.01) and volume (p = 0.008) of internal border zone infarcts in the hemisphere ipsilateral to the occluded ICA. Absence of collateral blood flow via the circle of Willis was associated with an increase in prevalence (p = 0.007) and volume (p = 0.005) of internal border zone infarcts. No association between any collateral flow pattern in the circle of Willis and periventricular lesions or lacunar, territorial, or external border zone infarcts was found. No association between collateral flow via the ophthalmic artery or leptomeningeal vessels with any type of ischemic lesion was found. Conclusion: Collateral flow via the ACoA is associated with a reduction of the prevalence and volume of internal border zone lesions but not with any other type of ischemic lesion. The presence of a functional posterior communicating artery or secondary collateral pathways is not associated with the prevalence of any type of ischemic lesion.