The purpose of this study is to determine how well patients perform on a battery of tests of brain function before and after surgery to correct narrowing in the carotid artery. This study will serve as a pilot project (a) to determine incidence of neurologic neuropsychometric change in patients undergoing this type of surgery, and (b) to ascetain the time it takes for these changes to resolve. To determine that the changes seen in patients having carotid artery surgery are not due to the anesthesia, we will also study a control group consisting of patients having spine surgery. To verify brain injury, patients for carotid artery surgery will have three types of evaluations before and after carotid artery surgery: a clinical examination consisting of a neurological and neuropsychological evaluation, blood test consisting of enzymes normally localized to the brain, and an MRI scan to look for structural changes in the brain that confirm cerebral injury. To determine one of the possible causes of brain injury, a transcranial Doppler ultrasound will be applied to the side of the head to examine a major vessel in the brain and see particles in these vessels called emboli.