Introduction: There is conflicting data on the effect of carotid revascularization on cognitive function. This study examines cerebral blood flow and cognitive function.

Methods: Patients with unilateral asymptomatic >80% carotid stenosis were eligible. Cerebral blood flow was measured preoperatively and 1 month postoperatively using quanititative phase contrast magnetic resonance angiography. Preoperative flow impairment was defined as ipsilateral flow at least 20% less than contralateral flow (i.e. an ipsilateral/contralateral flow ratio <0.8). Improvement in blood flow was defined as a 0.15 increase in flow ratio from pre- to postoperative. Revascularization was via carotid endarterectomy (CEA) or stent (CAS). A control group was managed medically. Four cognitive domains (Trails A, Trails B, verbal fluency, and memory) were assessed at baseline and 6-12 postoperatively.

Results: Seventy five patients were enrolled at 6 sites; 53 CEA, 11 CAS, and 11 control patients. ICA flow limitation was observed in 57% of the population. Revascularization significantly improved ICA flow in 68% of surgical patients, and in only 9% (1/11) control patients (p=0.0002). For patients with ICA flow improvement, 26 % also exhibited ipsilateral MCA flow improvement. Analysis focused on Trails B because other cognitive assessments improved in both control and revascularization groups. Preoperative Trail B scores were similar between groups (p=0.14). Revascularization was associated with significant improvement in executive function (Trails B) while no improvement was noted in controls (p=0.007). Of patients with improvement in MCA flow, 90% improved Trails B scores, while only 46.5% without MCA flow improvement improved in Trails B (p=0.01). Greater improvement in Trail B scores was observed in patients with MCA flow improvement compared to those without (48.6s ± 41.3 vs. 10.49s ± 24.7, p=0.001). (Figure 1).

Conclusions: In a cohort of patients with asymptomatic carotid stenosis, improvement in MCA flow following carotid revascularization is associated with improvement in executive functioning.

Patient Care: Learners will consider cognitive function when advising patients with unilateral carotid stenosis about revascularization or not.

Learning Objectives: 1) To understand qMRA flow assessment in the brain 2) To understand cognitive assessment in patients with carotid stenosis

References: Ghogawala Z, Amin-Hanjani S, Curran J, et al. The effect of carotid endarterectomy on cerebral blood flow and cognitive function. Journal of stroke and cerebrovascular diseases : the official journal of National Stroke Association. Oct 2013;22(7):1029-1037.