Sponsor: NINDS

Principle Investigator: William J Powers, MD, University of North Carolina, Department of Neurology

Site P.I.: Randolph S. Marshall, MS, MD, Columbia University Medical Center, Department of Neurology

The Carotid Occlusion Surgery Study (COSS) is an NIH-sponsored randomized clinical trial to test the hypothesis that intracranial-extracranial (EC-IC) bypass surgery can reduce by 40% the chance of stroke at two years in patients with recently symptomatic internal carotid artery occlusion and ipsilateral increased oxygen extraction fraction as measured by PET.

Patients must have an occlusion of 1 carotid artery as documented by Doppler, magnetic resonance angiography (MRA), computed tomographic angiography (CTA) or conventional angiography, and have had symptoms (TIA or stroke) within 120 days of enrollment in the study. In the trial patients first undergo positron emission tomography (PET) to determine whether their cerebral blood flow is significantly impaired. If the blood flow is shown to be low by PET, patients are randomized (like a flip of a coin) to receive either EC-IC bypass or best medical therapy alone. Patients in both treatment groups are followed every 3 months for examinations, blood work, ultrasound, and maximization of their medical care. The study duration is 2 years for each patient.

Dr. Randolph Marshall is the Columbia Site PI for a study to determine the effectiveness of extracranial-intracranial bypass surgery in reducing the chance of stroke in someone who has complete blockage in one main artery in the neck (the carotid artery) that supplies blood to the brain. The technique of extracranial-intracranial arterial bypass surgery was developed in the late 1960s 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.

Eligible Participants: Adults between the ages of 18-85 inclusive with: (1) vascular imaging demonstrating occlusion of one internal carotid artery and less than 50% stenosis of the contralateral extracranial internal carotid artery; (2) transient ischemic attack (TIA) or ischemic stroke in the hemispheric territory of the occluded carotid artery within 120 days of enrollment.

Participation Includes: Qualified patients receive a PET Scan to determine eligibility for randomization into the surgical or medical arm.

If you are interested in participating or have any questions about research studies, please e-mail or call