Carotid artery disease and cognitive impairment

The term neurologic symptom usually relates to the loss of motor or sensory functions; cognitive deficit is mostly unrecognized in patients with severe carotid stenosis. In large population studies carotid stenosis has been shown as independent risk factor for mild cognitive impairment (MCI) and it was not due to underlying vascular risk factors. The term MCI refers to a transitional stage between cognitive changes of normal aging and vascular dementia. At this stage, cognitive decline is not severe enough to constitute dementia, but also it is beyond the cognitive functioning deficit which is expected in normal aging. Carotid stenosis detected in population older than 65 is 75% for men and 62% for women, with prevalence of stenosis ≥ 50% in this population 7% for men and 5% for women. There are two possible underlying pathomorphological mechanisms of cognitive changes in patients with carotid disease - cerebral emboli and hypoperfusion with or without silent brain infarctions. In both cases loss of regional cerebral autoregulation can be recognized by means of neurosonology (transcranial Doppler ultrasonography). Most of the studies which evaluated cognitive functions before and after CEA/CAS have shown improvement or no changes in cognitive functions, but no deteriorations. There are still no clear recommendations about using CEA/CAS in treating cognitive deficit in otherwise asymptomatic patients. It is important to recognize cognitive changes as a symptom of carotid disease in order to follow up such patients and include cognitive deficit as one of the criteria in calculating perioperative risk and benefit from CEA/CAS.