The results of the recently published Carotid Occlusion Surgery Study, which failed to show a benefit of extracranial-intracranial (EC-IC) bypass over medical therapy in patients with symptomatic hemodynamically significant carotid occlusion, have been interpreted by some as the end of the line for EC-IC bypass in the management of stroke. Despite being carefully conceived and executed, several aspects of the trial design, study population, and underlying assumptions deserve further examination to determine how best to translate these results into clinical practice. Although a general expansion of EC-IC bypass use in this population would not be supported by the trial results, a select subset of patients with medically refractory hemodynamic symptoms may well benefit from surgery performed with sufficiently low perioperative morbidity. The potential for beneficial functional or cognitive impact of revascularization also remains under investigation. Limited application and further study with an eye to future developments, rather than complete abandonment, is warranted.
ABBREVIATIONS: COSS, Carotid Occlusion Surgery Study
MCA, middle cerebral artery
OEF, oxygen extraction fraction
PET, positron emission tomographic
STA, superficial temporal artery