Improvement of cognitive function after carotid endarterectomy--a new strategy for the evaluation of cognitive function.

Significant carotid stenosis is known to cause ischemic stroke and cognitive impairment. However, it remains controversial whether carotid endarterectomy (CEA) can improve cognitive function in patients with carotid stenosis. We used the Montreal Cognitive Assessment (MoCA) and Mini-Mental State Examination (MMSE) to compare cognitive function between before and after CEA. Patients were prospectively registered to evaluate cognitive function from October 2011 to December 2012 after we determined them to have significant carotid stenosis. Patients were examined by 3-dimensional computed tomographic angiography or digital subtraction angiography. Although symptomatic cases were included, their modified Rankin Scale was grade 0 or 1 before CEA. All CEA procedures were performed by the same neurosurgical team. Cognitive function was evaluated by MoCA and MMSE performed before and after surgery. Data were analyzed statistically using the Wilcoxon signed rank test. Thirty-six patients were included in this study. The MoCA score after surgery, whereas the MMSE score was not. After surgery, the MoCA score improved in patients who were 73 years or younger, who underwent CEA in the left side of their carotid lesion, who had severe carotid stenosis of more than 80%, who had bilateral lesion, who did not have abnormal lesion on diffusion-weighted imaging after surgery, or who had cerebral blood flow of pre-CEA over 34.5 mL. In conclusion, MoCA was feasible in patients soon after undergoing CEA. Using MoCA not MMSE, CEA may improve cognitive function in patients with significant carotid stenosis.