Cerebral Hemodynamics and Stroke Risk in Patients with Complete Carotid Artery Occlusion: Is There a Role for Cerebral Revascularization?

Abstract

Patients with complete carotid artery occlusion comprise approximately 15% of those with carotid territory transient ischemic attacks or infarction [1, 2, 3]. Prevention of subsequent stroke in patients with carotid artery occlusion remains a difficult challenge. The overall risk of subsequent stroke is 7% per year and the risk of stroke ipsilateral to the occluded carotid artery is 5.9% per year [4]. These risks persist in the face of platelet inhibitory drugs and anticoagulants [5]. The importance of hemodynamic factors in the prognosis of carotid occlusion and the role of surgical re-vascularization in the treatment of these patients has been a subject of controversy for many years. The technique of extracranial-intracranial (EC/IC) arterial bypass surgery was developed in the late 1960’s and applied to patients with carotid occlusion in an attempt to prevent subsequent stroke by improving the hemodynamic status of the cerebral circulation distal to the occluded vessel. The results of an international multicenter randomized trial to determine the efficacy of EC/IC arterial bypass for the prevention of subsequent stroke was reported in 1985. Among 808 patients with symptomatic carotid occlusion who were randomized, no benefit of superficial temporal artery — middle cerebral artery (STA-MCA) bypass surgery could be demonstrated [6]. Based on the results of this trial, EC/IC bypass was generally abandoned as a treatment for symptomatic carotid artery occlusion.