Introduction: Low cerebral blood flow can affect cognition in patients with high-grade asymptomatic internal carotid artery stenosis. Current clinical algorithms use stroke risk to determine which patients should undergo revascularization without considering cognitive decline. Although correlations between low-flow and cognitive impairment have been reported, it is not known whether a threshold exists below which such a correlation expresses itself. Such information would be critical in treatment decisions about whether to intervene in patients with high-grade carotid artery stenosis who are at risk for cognitive decline. Objective: To determine how reduced blood flow correlates with lower cognitive scores. Methods: Patients with ≥80% unilateral internal carotid artery stenosis with no history of stroke were recruited from inpatient and outpatient practices at a single, large, comprehensive stroke center. Patients underwent bilateral insonation of middle cerebral arteries with standard 2-Hz probes over the temporal windows with transcranial Doppler. Cognitive assessments were performed by an experienced neuropsychologist using a cognitive battery comprising 14 standardized tests with normative samples grouped by age. Z-scores were generated for each test and averaged to obtain a composite Z-score for each patient. Multivariable linear regression examined associations between mean flow velocity (MFV) and composite Z-score, adjusting for age, education, and depression. The Davies test was used to determine if there was a breakpoint for a non-zero difference in slope of a segmented relationship over the range of composite Z-score values. Results: Forty-two patients with unilateral high-grade internal carotid artery stenosis without stroke were enrolled (26 males, age = 74 ± 9 years, education = 16 ± 3 years). Average composite Z-score was –0.31 SD below the age-specific normative mean (range –2.8 to +1.2 SD). In linear regression adjusted for age, education, and depression, MFV correlated with cognitive Z-score (β = 0.308, p = 0.043). A single breakpoint in the range of composite Z-scores was identified at 45 cm/s. For MFV #x3c;45 cm/s, Z-score decreased 0.05 SD per cm/s MFV (95% CI: 0.01–0.10). For MFV #x3e;45 cm/s, Z-score change was nonsignificant (95% CI: –0.07 to 0.05). Conclusions: In high-grade, asymptomatic carotid artery stenosis, cognitive impairment correlated linearly with lower flow in the hemisphere fed by the occluded internal carotid artery, but only below a threshold of MFV = 45 cm/s. Identifying a hemodynamic threshold for cognitive decline using a simple, noninvasive method may influence revascularization decision-making in otherwise “asymptomatic” carotid disease.
Cerebrovasc Dis Extra 2020;10:21–27

中文翻译：

---

认知障碍与经颅多普勒平均血流速度线性相关的阈值以下。

简介：脑血流量低会影响高度无症状颈内动脉狭窄患者的认知。当前的临床算法使用中风风险来确定哪些患者应进行血运重建而不考虑认知能力下降。尽管已经报道了低血流与认知障碍之间的相关性，但尚不知道是否存在阈值，低于该阈值便会表现出这种相关性。这些信息对于决定是否干预患有认知功能下降风险的高级别颈动脉狭窄患者的治疗决策至关重要。目的：确定血流量减少与较低的认知评分之间的关​​系。方法：从单一的大型综合性卒中中心的住院和门诊实践中招募≥80％的单侧颈内动脉狭窄且无卒中史的患者。患者使用经颅多普勒在颞窗上用标准的2 Hz探头对中脑动脉进行双侧声波检查。认知评估是由经验丰富的神经心理学家使用认知电池进行的，该认知电池包括14种标准化测试，并按年龄对标准样本进行了分组。为每个测试生成Z分数，并取平均值以获取每个患者的复合Z分数。多变量线性回归检查了平均流速（MFV）与复合Z评分之间的关​​联，并针对年龄，学历和抑郁进行了调整。结果：招募了42例无卒中的单侧高级别颈内动脉狭窄患者（男26例，年龄= 74±9岁，学历= 16±3岁）。平均综合Z值比特定年龄的规范平均值低–0.31 SD（范围为–2.8至+1.2 SD）。在根据年龄，教育程度和抑郁进行了线性回归后，MFV与认知Z评分相关（β= 0.308， p = 0.043）。确定复合Z值范围内的单个断点为45 cm / s。对于MFV＃x3c； 45 cm / s，Z分数每cm / s MFV降低0.05 SD（95％CI：0.01–0.10）。对于MFV＃x3e； 45 cm / s，Z值变化不明显（95％CI：–0.07至0.05）。结论：在高度，无症状的颈动脉狭窄中，认知障碍与受阻颈内动脉供血的半球血流减少呈线性相关，但仅低于MFV = 45 cm / s的阈值。使用简单，无创的方法确定认知功能减退的血流动力学阈值可能会影响否则为“无症状”的颈动脉疾病的血运重建决策。
Cerebrovasc Dis Extra 2020; 10：21–27