Neurocognitive changes after carotid revascularization according to perfusion parameters: a meta-analysis of current literature

Abstract Background and Purpose Although the clinical outcomes continue to be scrutinized, there are few data summarizing the changes in perfusion parameters in postoperative patients. The objective was to undertake a systematic literature review and perform a meta-analysis to assess the effects of cerebral perfusion changes in cognitive and functional status. Methods A systematic search was conducted in July 2018 identifying articles comparing perfusion parameters changes before and after carotid revascularization in patients with carotid artery stenosis. Combined overall effect sizes were calculated using random effects models. Results The literature search identified 1031 unique articles was eligible for analysis. Sixteen studies, including 755 patients were identified. The studies were different for many methodological factors, e.g., sample size, type of patients, statistical measure, type of test, timing of assessment, and so on. There were no differences in cerebral blood volume (CBV), cerebral metabolic rate of oxygen (CMRO 2 ), and relative cerebral blood volume (rCBV) between pre- and post-intervention, but there was a significant increase of cerebral blood flow (CBF) (95% CI Std. MD: -0.83[-1.27, -0.40]; P = 0.0002; I 2 =68%) and relative cerebral blood flow (rCBF) (95% CI Std. MD: -0.72[-1.61, -0.27]; P 2 =48%) after operation. In addition, the perfusion of mean transit time (MTT) (95% CI Std. MD: 1.26[0.62, 1.90]; P=0.0001; I 2 =84%), oxygen extraction fraction (OEF) (95% CI Std. MD: 0.78[0.24, 1.33]; P=0.005; I 2 =0%), time to peak (TTP) (95% CI Std. MD: 0.46[0.16, 0.77]; P=0.003; I 2 =47%) and relative mean transit time (rMTT) (95% CI Std. MD: 0.41[0.33, 0.50]; P 2 =67%) was higher before than after operation. Conclusions The changes in CBF and rCBF increase and the decrease in MTT, OEF, TTP and rMTT after operation may indicate the improvement of cognition in the short term. Intraoperative perfusion parameters could be an important adjuvant monitoring method in neurocognitive changes after carotid revascularization.