Patients will undergo an intraprocedural transcranial Doppler ultrasonograph (TCD). TCD monitoring probes will be placed on the patient's head with a standard head frame after sedation, one probe on each side to measure the cerebral blood flow (CBF) velocity and determine the presence of emboli in the middle cerebral artery (MCA) on either side of the brain (Spencer Technologies, Seattle, WA). We hypothesize that there may be a relationship between emboli and subtle cognitive decline as ascertained by the battery of neuropsychometric exams. An electroencephalogram (EEG) will be applied to monitor for significant hemispheric cerebral ischemia which may occur when the balloon is inflated and occludes the artery. We routinely use EEG monitoring during carotid endarterectomy and its use exposes the patient to no risk.