Posterior Cerebral Artery Perfusion Is Associated With Cognitive Prognosis After Endarterectomy in Patients With Asymptomatic Severe Carotid Stenosis

Severe carotid stenosis patients with declined baseline cognition has been reported in the CREST-2, and the question of whether cognition can be improved after carotid endarterectomy (CEA) remains unanswered. Alterations in cerebral blood flow are the direct physiological changes after CEA. This study investigated the relationship between cerebral blood perfusion and cognitive function after CEA in patients with severe asymptomatic carotid artery stenosis, with the aim of identifying target populations that may benefit from improved cognition after CEA. This is a prospective observational cohort study. Patients with unilateral, severe, asymptomatic carotid stenosis were included. Computerized tomography cerebral perfusion, cognitive tests, and quantitative electroencephalogram (qEEG) analysis were performed preoperatively and 6 months postoperatively (Fig 1). Regions of interest (ROIs) were selected based on the blood supply areas of the anterior, middle, and posterior cerebral arteries. Using the contralateral hemisphere as a reference, we determined preoperative impaired perfusion and the postoperative improvement status of each region on the severe stenosis side and compared the cognitive test scores and qEEG characteristics of patients with different perfusion status. A total of 52 individuals were included in the analysis to date (Fig 1), with 75.0% male patients and a mean age of 60.4 ± 7.1 years (Table I). Preoperatively, 61.5%, 55.4%, and 30.4% of patients exhibited impaired perfusion in the anterior, middle, and posterior artery supply ROIs, respectively. Among them, patients with impaired posterior perfusion demonstrated significantly poorer baseline cognitive scores (Table II). In addition, individuals with impaired posterior circulation perfusion exhibited a characteristic reduction in ipsilateral occipital γ-band activity (Fig 2). Six months postoperatively, there was an improvement in perfusion for 56.7%, 45.4%, and 21.8% of cases in the anterior, middle, and posterior artery supply regions, respectively. Patients with improved posterior perfusion showed a significant improvement in cognitive scores, particularly in the memory test (Rey Auditory Verbal Learning Test Z score change: 0.67 vs −0.14, P = .002) (Table III). Moreover, postoperative occipital γ-band activity was restored to the symmetrical levels of the contralateral hemisphere. Clinical analysis showed that severe stenosis of the vertebral/basilar arteries was higher in patients with posterior perfusion impairment (78.6% vs 28.9%, P = .002) and was significantly associated with improved cognitive test scores after CEA (β coefficient = 1.36, 95% CI: 0.33-2.38, P = .01). Severe asymptomatic carotid stenosis patients with impaired posterior perfusion may be the population that benefits from cognitive function after CEA. The presence of concomitant vertebrobasilar artery stenosis and lower γ-band activity may serve as predictive factors.Fig 2Patients with impaired posterior cerebral artery perfusion showed a reduction in γ-band activity on the ipsilateral occipital region. *indicates a significant decrease in power spectral density on the ipsilateral hemisphere compared with the contralateral side.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Table IDemographic data and carotid lesion characteristics (N = 52)CharacteristicValueAge, years60.4 ± 7.1Male39 (75.0)Education years8.3 ± 2.1Tobacco25 (48.1)Hypertension26 (50.0)Coronary disease20 (38.5)Type 2 diabetes24 (46.2)Hyperlipidemia42 (80.8)Ipsilateral lacunar infarction14 (26.9)Carotid artery lesions Right lesion10 (19.2) Ipsilateral degree of stenosis, %≤70070-9024 (46.2)≥9028 (53.9) Contralateral degree of stenosis, %≤3038 (73.1)30-5014 (26.9)≥500Data are presented as number (%) or mean ± standard deviation. Open table in a new tab Table IIBaseline cognitive scores at different preoperative ipsilateral perfusion status in cerebral arteries supply regions of interest (ROIs)Anterior cerebral arteryMiddle cerebral arteryPosterior cerebral arteryImpaired perfusion groupsymmetrical perfusion groupImpaired perfusion groupsymmetrical perfusion groupImpaired perfusion groupsymmetrical perfusion groupTMT-A45.1 ± 1150.3 ± 18.844.8 ± 10.651 ± 19.457.8 ± 23.2a45.5 ± 12.7TMT-B66.4 ± 17.172.3 ± 21.665.3 ± 16.873.8 ± 14.692.3 ± 19.4a64.1 ± 15.5VFT35.5 ± 10.936.1 ± 1436.2 ± 10.835.4 ± 14.327 ± 14.4a37.9 ± 11.3SDMT18 ± 5.618.6 ± 4.518.1 ± 5.318.6 ± 4.714.5 ± 6.519.3 ± 4.1RAVLT42.3 ± 11.737 ± 10.941.9 ± 11.337.9 ± 11.429.5 ± 5.9a41.8 ± 11.3BNT22.3 ± 2.220.4 ± 3.224.0 ± 2.821.3 ± 3.221.2 ± 3.223.6 ± 2.2Zsum−0.290.120.110.21−1.04a0.25Zsum value is obtained by averaging the sum of Z scores from all cognitive tests.aIndicates a significant difference in cognitive scores compared with the symmetrical perfusion group, P < .05. Trial making test-A/B (TMT-A/B): attention, visuospatial, executive. Verbal fluency test (VFT): language, semantic memory, executive. Symbol digit modalities test (SDMT): working memory, information processing. Boston Naming Test (BNT): language, Visual naming. Rey Auditory Verbal Learning Test (RAVLT): memory. Open table in a new tab Table IIICognitive scores change according to different postoperative perfusion status in cerebral arteries supply regions of interest (ROIs)Anterior cerebral arteryMiddle cerebral arteryPosterior cerebral arteryPerfusion Improvement groupPerfusion unchanged groupPerfusion Improvement groupPerfusion unchanged groupPerfusion Improvement groupPerfusion unchanged groupTMT-A△–.0100.080.090.08–0.110.02TMT-B△–0.200.160.020.170.27a–0.06VFT△0.010.00–0.01–0.040.03–0.07DSCT△0.02–0.020.12–0.110.22–0.05RAVLT△–0.010.09–0.040.030.67a–0.14BNT△0.110.22–0.03–0.040.030.05Zsum△–0.190.310.120.190.83a–0.17BNT, Boston Naming Test; RAVLT, Rey Auditory Verbal Learning Test; TMT-A/B, trial making test-A/B; VFT, verbal fluency test.The change in each test is represented by Δ, calculated as the difference between postoperative Z values and preoperative Z values. The overall change in cognitive scores (ZsumΔ) is determined by averaging the differences between postoperative and preoperative Z scores across all cognitive tests.aIndicates a significant difference in cognitive scores compared with the symmetrical perfusion group, P < .05. Open table in a new tab