Birns J, Jarosz J, Markus H S, Kalra L
Department of Stroke Medicine, Academic Neurosciences Centre, PO41, Institute of Psychiatry, King's College London, London, UK.
J Neurol Neurosurg Psychiatry. 2009 Oct;80(10):1093-8. doi: 10.1136/jnnp.2009.174607. Epub 2009 Jun 16.
It has been suggested that impaired cerebral autoregulation and vasodilatory capacity may play in role in the pathogenesis of the leukoaraiosis seen in small vessel disease. Adequate perfusion of the deep white matter of the brain depends on the relationships between blood pressure (BP), cerebral vasoreactivity and autoregulation.
24 h ambulatory BP measurement, quantitative volumetric MRI analysis of white matter lesion (WML) volume and transcranial Doppler ultrasound assessments of CO(2) reactivity in response to hypercapnia and dynamic cerebral autoregulatory index (ARI) were undertaken in 64 patients with cerebral small vessel disease.
Subjects had mean 24 h BP 133/76 mm Hg (SD 13/9), median WML volume 7169 (IQR 20497) mm(3), mean CO(2) reactivity 83.6 (SD 37.4)% and mean ARI 5.6 (SD 1.4) (range 0-9). In multivariate models, after adjusting for age, gender, vascular risk profile and WML volume, ARI correlated with 24 h mean BP levels (R(2) = 0.127, t = 2.440, p = 0.019) and CO(2) reactivity correlated with duration of hypertension (R(2) = 0.085, t = -2.244, p = 0.029). In individuals with hypertension for more than 10 years, ARI also correlated with nocturnal BP dipping (r = 0.806, p = 0.002). ARI and CO(2) reactivity were unaffected by WML volumes, and ARI and CO(2) reactivity were unrelated.
Cerebral autoregulation and CO(2) reactivity are two distinct processes which are not related to WML volume but are related to BP levels and duration of hypertension, respectively. Greater nocturnal dipping was associated with higher ARI values, suggesting preservation of autoregulation in patients with increased vulnerability to reduced cerebral perfusion.
有人提出，脑自动调节功能受损和血管舒张能力可能在小血管疾病中白质疏松症的发病机制中起作用。脑深部白质的充分灌注取决于血压（BP）、脑血管反应性和自动调节之间的关系。
对64例脑小血管疾病患者进行24小时动态血压测量、白质病变（WML）体积的定量容积磁共振成像分析以及对高碳酸血症反应的经颅多普勒超声评估二氧化碳反应性和动态脑自动调节指数（ARI）。
受试者的24小时平均血压为133/76 mmHg（标准差13/9），WML体积中位数为7169（四分位间距20497）mm³，平均二氧化碳反应性为83.6（标准差37.4）%，平均ARI为5.6（标准差1.4）（范围0 - 9）。在多变量模型中，在调整年龄、性别、血管风险状况和WML体积后，ARI与24小时平均血压水平相关（R² = 0.127，t = 2.440，p = 0.019），二氧化碳反应性与高血压持续时间相关（R² = 0.085，t = -2.244，p = 0.029）。在高血压超过10年的个体中，ARI也与夜间血压下降相关（r = 0.806，p = 0.002）。ARI和二氧化碳反应性不受WML体积的影响，且ARI与二氧化碳反应性无关。
脑自动调节和二氧化碳反应性是两个不同的过程，它们与WML体积无关，但分别与血压水平和高血压持续时间有关。更大的夜间血压下降与更高的ARI值相关，提示在脑灌注减少易感性增加的患者中自动调节功能得以保留。
