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AJNR - American Journal of Neuroradiology

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American Journal of Neuroradiology 26:2086-2094, September 2005
© 2005 American Society of Neuroradiology

HEAD AND NECK

Identification, Prognosis, and Management of Patients with Carotid Artery Near Occlusion

Allan J. Fox^a, Michael Eliasziw^d, Peter M. Rothwell^e, Matthias H. Schmidt^c, Charles P. Warlow^f, Henry J.M. Barnett^b for the North American Symptomatic Carotid Endarterectomy Trial and European Carotid Surgery Trial Groups

^a Department of Medical Imaging, Sunnybrook and Women’s College Health Sciences Center, University of Toronto, Toronto
^b John P. Robarts Research Institute, London, Ontario, Canada
^c Department of Diagnostic Imaging, IWK Health Centre, and Department of Radiology, Dalhousie University, Halifax, Nova Scotia, Canada
^d Departments of Community Health Sciences and Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada
^e Stroke Prevention Research Unit, University Department of Clinical Neurology, Radcliffe Infirmary, University of Oxford, Oxford, United Kingdom
^f Department of Clinical Neurosciences, Western General Hospital, University of Edinburgh, Edinburgh, United Kingdom

Address correspondence to Allan J. Fox, MD, Neuroradiology, Sunnybrook and Women’s College Health Sciences Center, 2075 Bayview Avenue, Room AG31b, Toronto, Ontario M4N 3M5, Canada

BACKGROUND AND PURPOSE: Two large trials indicated that endarterectomy was less beneficial for symptomatic patients with internal carotid artery (ICA) near occlusion than for patients who had severe stenosis without near occlusion. Near occlusions complicate ratio calculations of ICA stenosis and require attention to detail for identification. The goal is to provide diagnostic criteria, illustrate identifying features, estimate accuracy of identification, and assess prognosis for patients with near occlusion.

METHODS:We re-reviewed 1216 patients with severe (70%) stenosis on angiography in the North American Symptomatic Carotid Endarterectomy Trial and European Carotid Surgery Trial. One of 5 (n = 262) had 2 or more criteria for near occlusion: (1) delayed cranial arrival of ICA contrast compared with external carotid artery (ECA); (2) intracranial collaterals seen as cross-filling of contralateral vessels or ipsilateral contrast dilution; (3) obvious diameter reduction of ICA compared with opposite ICA; or (4) ICA diameter reduction compared with ipsilateral ECA.

RESULTS: Interrater agreement, sensitivity, and specificity were excellent (0.88, 90.6%, and 93.8%, respectively). By intention to treat, 3-year risks of ipsilateral stroke for medically treated patients with near occlusion was 15.1% versus 10.9% for surgically treated (absolute risk reduction [ARR] = 4.2%; P value = .33). Patients who continued to receive treatment in the medical arm for the trial’s duration had a 3-year risk of 18.3% (ARR = 7.4%; P value = .13). Medically treated patients with severe stenosis but without near occlusion had a 3-year risk of 26.0% versus surgically treated of 8.2% (ARR = 17.8%; P value < .001).

CONCLUSION: It is crucial to identify near occlusions on vascular imaging. Although it still is reasonable to consider endarterectomy for these patients, the benefit is muted.

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