Indications for cerebral revascularization for patients with atherosclerotic carotid occlusion

Abstract

Patients with complete carotid occlusion and recent ischemic symptoms are at high risk for subsequent stroke, particularly those with evidence of severe hemodynamic impairment due to poor collateral flow. Treatment options for these patients include direct extracranial to intracranial arterial bypass, or interventions aimed at improving collateral sources of flow such as endarterectomy or angioplasty and stenting of the ipsilateral external carotid artery, the contralateral carotid artery, or the vertebral arteries. The evidence supporting the use of these procedures for patients with complete occlusion of the carotid artery will be the focus of this article. The use of physiologic imaging to select subgroups of patients at high risk due to hemodynamic factors will also be discussed.

Figure 1

Fluid attenuated inversion recovery (FLAIR) magnetic resonance (MR) image of a 35-year-old woman with moyamoya disease demonstrating bilateral centrum semiovale white matter infarctions. This pattern of infarction is associated with hemodynamic impairment. A small right motor cortex infarction is also present, corresponding to a minor stroke affecting her left hand.

Figure 2

Compensatory increase in OEF as identified by PET. These images are from a neurologically normal patient with a unilateral carotid occlusion due to atherosclerosis. CBF is reduced on the left image (CBF, arrows). Oxygen metabolism is normal, however (CMRO₂, middle image), owing to a compensatory increase in oxygen extraction (OEF, right image, arrows). OEF, oxygen extraction fraction; PET, positron emission tomography; CBF, cerebral blood flow.

Figure 3

The frequency of stroke may be higher during the first 2 years of follow-up for the 81 symptomatic patients with atherosclerotic carotid artery occlusion enrolled in the St. Louis Carotid Occlusion Study. The left axis is the left-to-right hemispheric ratio of OEF. The dotted lines indication the normal range—values above or below the line indicate increased OEF beyond the normal range. The x-axis indicates the duration of follow-up after enrollment for patients without stroke and the time of stroke after enrollment for patients suffering stroke during the follow-up period. OEF, oxygen extraction fraction.