The number of microembolic signals (MES) detected in the middle cerebral artery (MCA) downstream to a symptomatic carotid stenosis by transcranial Doppler sonography (TCD) has been shown to predict the stroke risk, and is dramatically reduced in patients with acute ischemic stroke not caused by carotid artery disease during the administration of the GP IIb/IIIa inhibitor tirofiban. These data suggest that the monitoring of MES in the MCA distal to a symptomatic carotid stenosis before and after the administration of abciximab may be a useful surrogate marker to assess the efficacy of this drug to prevent MES and stroke in patients with symptomatic carotid stenosis. Diffusion-weighted MR imaging (DWI) has a high sensitivity for detecting acute brain ischemia, and recent DWI studies have assessed the incidence of asymptomatic ischemic brain lesions in patients who underwent CEA.