Can we identify patients with carotid occlusion who would benefit from EC/IC bypass? Review.

Occlusion of the internal carotid artery (CAO) is associated with a high mortality rate and frequent disability in survivors. Even in patients with good clinical recovery there is a high risk of recurrent stroke, mainly in those with impaired cerebral vasomotor reactivity (CVR). Current evidence based therapeutic options for patients with symptomatic CAO include antithrombotic medication and control of vascular risk factors. For stenosis of the contralateral internal or ipsilateral external carotid artery, endarterectomy or percutaneous transluminal angioplasty may be considered. Ongoing symptoms may cease after tapering antihypertensive medications. Extracranial to intracranial (EC/IC) arterial bypass surgery has been used since 1967 in patients with CAO. However, the international randomized EC/IC Bypass Study (1985) failed to confirm the effectiveness of EC/IC bypass for preventing cerebral ischemia in patients with symptomatic CAO when compared to those assigned to the best medical care. Nevertheless, the conclusion of the EC/IC Bypass Study has several objections and downfalls. Since then, there has been a revival of interest in cerebral revascularization procedures owing to the substantial progression of surgical techniques and the use of more advanced diagnostic methods. Thus, it has recently been reported that EC/IC bypass surgery can be useful in preventing stroke in patients with hemodynamic compromise. The main problem is to identify the small subgroup of surgical candidates. Presently, single photon emission computed tomography (SPECT), positron emission tomography (PET), transcranial Doppler sonography (TCD), computed tomography (CT) with administration of (133)Xe, perfusion CT, near infrared spectroscopy (NIRS), and functional magnetic resonance imaging (fMRI) are being used for this purpose.