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OBJECTIVE: During carotid interventions there is a risk of distal cerebral embolization. Here we prospectively investigate whether subclinical microembolization seen on post-operative MRI leads to cognitive deficits in a cohort of patients undergoing either carotid endarterectomy (CEA) or carotid artery stenting (CAS).
METHODS: Patients undergoing carotid interventions and eligible for MRI scanning were recruited to participate. Among 247 patients who received both preoperative and postoperative MRI evaluations, a total of 51 patients also completed neuropsychological testing prior to the procedure and at one month following. Demographic data and MRI with diffusion weighted sequence (DWI) were collected for all patients. MRI with DWI was performed preoperatively and within 48 hours after the procedure. Cognitive function was evaluated using the Rey Auditory Verbal Learning Test (RAVLT) to evaluate memory and the Mini-Mental State Examination (MMSE) to screen for general cognitive impairment.
RESULTS: All 51 patients (16 CAS and 35 CEA) were male with a mean age of 71 years, ranging 54 to 89 years. Among them, 26 patients (51%) were symptomatic including 11 patients who had prior stroke and 15 patients who had prior TIA. The majority of the patients had significant medical comorbidities including hypertension (92%), diabetes (31.3%), coronary artery disease (47%), and COPD (15.7%). Thirteen patients (25%) had prior CEA and 7 had contralateral carotid occlusion (13.7%).
Memory decline evident on RAVLT was identified in 21 patients including 8 CAS patients and 13 CEA patients. There was no significant difference in baseline cognitive function or memory change between CEA and CAS cohort. Eleven patients had evidence of procedure-related microemboli. Multivariate regression analysis showed that procedure-related microembolization was associated with memory decline (P=0.016) as evident by change in RAVLT. Prior history of neurologic symptom was significantly associated with poor baseline cognitive function (MMSE) (P=0.03) and overall cognitive deterioration (change in MMSE) (P=0.026) as determined by Wilcoxon Rank Sum test and linear regression analysis respectively.
CONCLUSIONS: Although both CEA and CAS are effective in stroke prevention with minimal neurologic complication, neurocognitive effects remain uncertain. Procedure-associated microembolization and pre-existing neurologic symptoms are associated with poor baseline cognitive function and memory decline following the procedures. Further comprehensive cognitive evaluation to determine the benefit of carotid interventions is warranted.