Brain injury after carotid revascularization: outcomes, mechanisms, and opportunities for improvement

The most worrisome complication of carotid revascularization is neurologic injury, typically manifesting as a perioperative stroke. However, patients undergoing these procedures are at risk for a broad spectrum of neurologic injury. We sought to perform a systematic review of neurologic injury after carotid revascularization to guide future quality improvement efforts focused on reducing potentially preventable events.

Using a specified search strategy, we evaluated the mechanisms of neurologic injury, the measurement of neurobehavioral outcomes, and use of neuroimaging to evaluate carotid revascularization outcomes, and the application of these techniques in current registries and clinical trials of carotid revascularization.

We found that neurologic injury after carotid revascularization results from three broad etiologies: atheroembolic, thrombotic, and hypo/hyperperfusion. Broad variation exists across studies examining neurobehavioral outcomes. Of the 47 studies examining the effect of carotid endarterectomy on neurobehavioral functioning, 25 found that some aspect of cognition improved, 12 revealed no change in cognition, and 10 revealed declines in some aspect of cognition. There is a wide variation in the measurement of neurologic outcomes in clinical registries and trials. In reviewing 13 industry-sponsored registries of carotid artery stenting and 10 randomized trials of carotid endarterectomy and carotid artery stenting, registries were less likely to use validated neurologic assessment scales, independent neurologic examinations, and neuroimaging to establish outcomes than randomized trials.

Despite a considerable body of evidence, there is a lack of consensus in determining optimal strategies for the assessment and characterization of neurologic injury and its effect on neurobehavioral outcomes after carotid revascularization, especially among industry-sponsored trials. As a result, rates of neurologic outcomes varied considerably across studies, registries, and clinical trials. Future efforts to correlate neuroimaging with cognitive outcomes may offer insight into methods to decrease neurologic injury after carotid revascularization.