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(Stroke. 2008;39:3003.)
© 2008 American Heart Association, Inc.

Original Contributions

Assessment of the Contribution of the External Carotid Artery to Brain Perfusion in Patients With Internal Carotid Artery Occlusion

Peter Jan van Laar, MD, PhD; Jeroen van der Grond, PhD; Jochem P. Bremmer, MD; Catharina J.M. Klijn, MD, PhD Jeroen Hendrikse, MD, PhD

From the Departments of Radiology (P.J.v.L, J.v.d.G., J.H.) and Neurology (J.P.B., C.J.M.K.), University Medical Center Utrecht, Utrecht, The Netherlands; the Department of Radiology (P.J.v.L.), Meander Medical Center Amersfoort, Amersfoort, The Netherlands; and the Department of Radiology (J.v.d.G.), Leiden University Medical Center, Leiden, The Netherlands.

Correspondence to Peter Jan van Laar, MD, PhD, University Medical Center Utrecht, Department of Radiology, PO Box 85500, 3508 GA Utrecht, The Netherlands. E-mail p.j.vanlaar{at}umcutrecht.nl

Background and Purpose— The purpose of this study was to prospectively investigate the contribution of the ipsilateral external carotid artery (ECA) to cerebral perfusion in patients with internal carotid artery occlusion.

Methods— Institutional Review Board approval and informed consent were obtained. Thirty functionally independent patients (24 men, 6 women; mean age, 63 years) with an angiographically proven unilateral internal carotid artery occlusion and transient or minor disabling ischemic attacks ipsilateral to the side of the internal carotid artery occlusion were included. Grading of ECA collateral flow was performed with intraarterial digital subtraction angiography. The contribution of the ECA to regional cerebral blood flow was assessed with selective arterial spin labeling MRI. Differences in regional cerebral blood flow were analyzed with Student t test.

Results— Twenty percent of the patients had ECA Grade 0 collateral flow (no filling of ophthalmic artery), 20% Grade 1 (filling of carotid siphon), and 60% Grade 2 (filling of anterior and/or middle cerebral artery) as demonstrated on digital subtraction angiography. Although in the Grade 1 group, the ECA supplied a smaller region of the brain compared with the Grade 2 group, the mean regional cerebral blood flow of the perfusion territory supplied by the ECA is similar (P=0.70) in the Grade 1 group (mean±SD 57±16 mL/min/100 g) and the Grade 2 group (60±12 mL/min/100g).

Conclusion— In patients with symptomatic internal carotid artery occlusion, focal brain regions may strongly depend on the contribution to cerebral perfusion of the ECA ipsilateral to the side of the internal carotid artery occlusion, even in patients with limited ECA collateral supply as demonstrated on digital subtraction angiography.

Key Words: carotid artery occlusion • cerebral hemodynamics • collateral circulation • magnetic resonance imaging