Introduction: To determine if patients with extracranial carotid stenosis have improved blood flow and cognitive function following carotid revascularization.
Methods: Asymptomatic unilateral high grade carotid stenosis patients were included. Cerebral blood flow was measured pre-operatively and 1 month post-operatively using phase contrast qMRA. Pre-operative flow impairment was defined as an ipsilateral flow at least 20% less than contralateral flow. Improvement in flow was defined as an absolute increase of at least 0.10 in flow ratio from pre to post-operative assessment. Patients underwent cognitive testing pre-operatively and 1, 6, and 12 months post-operatively.
Results: A total of 84 patients were enrolled (59 carotid endarterectomy, 12 carotid stent, and 13 medical management). 78% completed follow-up at 6 months and/or 1 year. Mean age was 72 years, 61% were male. At last follow-up, statistically significant improvements in all four cognitive domains tests (Trail Making A, Trail Making B, Verbal Fluency, and HVLT) were observed following revascularization (P < 0.01). Medical management was not associated with flow improvement. For those who underwent revascularization, pre-operative flow impairment was associated with significant improvements in flow post-operatively in the ICA, MCA, and MCA+A2 vessels (P = 0.05) (Figure 1). Patients with flow improvement in the MCA + A2 vessels following revascularization were more likely to demonstrate clinically significant executive cognitive improvement (Trail Making B). In particular, 92% of patients with improvement in MCA+A2 flow demonstrated a clinically significant improvement in Trail Making B compared to only 40% of patients who did not demonstrate MCA + A2 flow improvement (P = 0.002) (Figure 2).
Conclusions: Carotid stenosis patients with baseline blood flow impairment were more likely to have improvement in flow following revascularization. Improvement in blood flow in MCA +A2 was associated with clinically significant improvement in executive cognitive function.
Patient Care: Understanding how carotid revascularization improves cerebral blood flow and the association between blood flow and cognitive function may make it possible to stratify populations of patients with carotid stenosis in terms of degree of flow impairment to better understand which patients stand to benefit cognitively from carotid revascularization.
Learning Objectives: 1. Describe how carotid revascularization affects cognitive outcome in patients with carotid artery stenosis.
2. Discuss improvement in cerebral blood flow among patients who undergo carotid revascularization for carotid artery stenosis.