Clinical significance of hemodynamic cerebral ischemia on cognitive function in carotid artery stenosis: a prospective study before and after revascularization

BACKGROUND: Carotid stenosis is known to have negative impacts on cognitive function. However, it is still unclear through which mechanisms cognitive function is impaired in patients with carotid stenosis. This study was aimed to clarify the impact of cerebral hemodynamics on cognitive function in carotid stenosis. METHODS: This prospective study included totally 109 patients with carotid stenosis who underwent carotid endarterectomy (CEA) or carotid artery stenting (CAS). Using N-isopropyl-p-[I-123]-iodoamphetamine SPECT, cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) to acetazolamide were quantitatively measured in all patients before and after CEA/CAS. Based on preoperative data, the patients were categorized into three groups: Type 1 (CBF >= 32 mL/min/100 g, CVR >= 10%), Type 2 (CBF >= 32 mL/min/100 g and CVR <10%), and Type 3 (CBF <32 mL/min/100 g and CVR <10%). White matter lesions were categorized according to Wahlund grading. Cognitive function was evaluated with Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) before and 3 months after CEA/CAS. RESULTS: Before CEA/CAS, total RBANS score was significant lower than the age-matched controls, 84 +/- 14 in Type 1 group (N.=56), 82 +/- 12 in Type 2 group (N.=43), and 70 +/- 12 in Type 3 group (N.=10). Especially, Type 3 patients had further lower score than Type 1 (P=0.008) and Type 2 (P=0.039) patients. There were no significant differences in white matter lesions among three groups. Total RBANS scores significantly improved at 3 months after CEA/CAS in all three groups, and the difference among them completely disappeared. CONCLUSIONS: These findings strongly suggest that carotid stenosis itself impairs cognitive function and compromised hemodynamic ischemia further declines it. CEA/CAS significantly improve cognitive function. The beneficial effects are most notable in patients with reduced CBF/CVR.