Purpose: Extracranial atherosclerotic carotid stenosis is associated with inadequate cerebral blood flow (CBF) and cognitive dysfunction. The impact of extracranial carotid revascularization on cognition and how any cognitive change relates to changes in CBF are less clear. This review examines the effects of revascularization of extracranial carotid disease by carotid endarterectomy (CEA) or carotid stenting (CAS) on cognition, and how this relates to changes in CBF.
Methods: A systematic review of existing reports in the Medline, Embase, and Cochrane databases was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis statement recommendations. All original retrospective or prospective studies and clinical trials that compared pre- and postoperative cognitive function and CBF in patients with extracranial carotid stenosis who underwent CEA or CAS versus a control group, published between January 1985 and December 2022, were identified and considered eligible for inclusion in this study.
Findings: Seven studies (661 participants; 460 CEA or CAS) were identified. All were observational studies and of moderate to good methodologic quality. Six studies (619 participants; follow-up range 1 month to 2 years) demonstrated improvement in some cognitive domains following CEA or CAS, improvement in CBF following revascularization, and correlated some of these cognitive changes with changes in CBF. One study (42 participants; 3 months follow-up) found cognitive improvement following CEA, but found no improvement in CBF or any correlation between cognitive and CBF change. The literature however represented heterogenous study populations examining asymptomatic and/or symptomatic carotid stenosis, differing in treatment modality and criteria for control groups ranging from healthy volunteers to those with stenosis but not who underwent surgical revascularization, and finally, differing reporting methods. This heterogeneity precluded meta-analysis.
Implications: Definitive conclusions are limited by variation in cognitive function assessment, timing of testing, and how these are correlated to CBF. However, research suggests a potential improvement in cognition which may be associated with improvement in CBF, particularly in those patients who have more significant CBF deficit at baseline. Further studies are required to better understand this association and provide a clearer picture of the cognitive effects of carotid revascularization.
Keywords: carotid atherosclerosis; cerebral blood flow; cognition; extracranial carotid revascularization.
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