Microembolization is commonly associated with carotid artery stenting (CAS), but our understanding of subclinical microembolization is superficial. Through collaborative effects of multidisciplinary team-experts, novel approaches, and longitudinal evaluations, we hope to better understand the clinical significance and long-term cognitive effects of microemboli. This proposal may change our current clinical practice by providing a better outcome measure for carotid interventions and improving outcomes of CAS procedures through risk factor stratification. Our central hypothesis is that development of subclinical microemboli is associated with decline in cognitive function following CAS and that the risk of development of microemboli themselves is associated with patient- and procedure-related factors. We hope that this prospective study will help to clarify these important issues in the era of rapidly evolving percutaneous interventions.

Inclusion Criteria:

• Patient is male or female >40 yrs of age.
• Patient has occlusive extracranial carotid stenosis (≥70%)
• Patient is scheduled to undergo an endovascular intervention of a lesion in the extracranial carotid artery
• Patient agrees to voluntarily participate and signs an informed consent.
• Patient agrees to be available for follow-up and is able to participate in all study testing procedures.
• Patient has sufficient visual and auditory acuity for cognitive testing.

Exclusion Criteria:

• Patient is unable to safely and comfortably undergo magnetic resonance imaging procedures (e.g., claustrophobia, implanted medical devices that are MRI incompatible such as pacemaker, defibrillator, neural stimulator etc)
• Patient has an untreated or unsuccessfully controlled psychiatric disease (schizophrenia, bipolar disorder).
• Patient has prominent suicidal or homicidal ideation.
• Patient has acute illness or unstable chronic illness (e.g. uncontrolled hypertension, hepatic encephalopathy, portal hypertension, ascites, and esophageal varices, pancreatitis).
• Patient with a history of neurological (e.g., multiple sclerosis, seizure disorder, Parkinson's disease) or systemic illness affecting central nervous system function.
• Patient has prior closed head injury with ≥24 hours of amnesia.
• Patient is unable to understand or sign the informed consent.

Patients undergoing carotid intervention