探讨症状性及无症状性脑小血管病变（SVD）颅内血流动力学变化，寻找经颅多普勒超声检查（TCD）诊断SVD的血流参数截断值。

连续性纳入2013年6月至2014年12月广州中医药大学第二临床医院收治的经头颅磁共振成像证实的SVD患者。所有患者均行磁共振血管成像（MRA）、颈部血管超声及TCD检查。记录脑白质病变程度、梗死灶数目与脑血流动力学参数。采用χ²检验比较症状性与无症状性SVD组患者脑白质病变程度；采用t检验比较症状性与无症状性SVD组患者脑血流参数；绘制脑血管搏动指数（PI）诊断症状性SVD患者的受试者工作特征（ROC）曲线。

无症状性SVD组患者脑白质疏松程度以0级、1级为主，分别34.6%（28/81）及35.8%（29/81），3级、4级均分别占14.8%（12/81）；症状性SVD组患者脑白质疏松程度以0级为最少，占15.7%（31/198），1级、2级、3级分别占29.8%（59/198）、29.3%（58/198）、25.3%（50/198）。无症状性SVD组患者脑白质疏松程度0级者比例多于症状性SVD组患者，而脑白质疏松程度2级、3级者比例少于症状性SVD组患者，且差异均有统计学意义（χ²=13.574，P=0.001；χ²=6.423，P=0.040；χ²=8.265，P=0.005）。症状性SVD组患者椎动脉、基底动脉平均流速均低于无症状性SVD组患者［（23.6±7.3）cm/s vs（27.8±7.0）cm/s，（31.9±10.3）cm/s vs（35.3±9.3）cm/s］，且差异均有统计学意义（t=4.269，P<0.001；t=2.500，P=0.013），而2组患者大脑前、中、后动脉平均流速差异均无统计学意义。症状性SVD组患者大脑前、中、后动脉、椎动脉、基底动脉PI指数均高于无症状性SVD组患者（0.99±0.17 vs 0.93±0.14，1.03±0.18 vs 0.96±0.15，0.98±0.17 vs 0.92±0.14，1.10±0.18 vs 1.04±0.23，1.09±0.21 vs 1.00±0.18），且差异均有统计学意义（t=-2.945，P=0.008；t=-2.616，P=0.003；t=-2.724，P=0.007；t=-3.323，P=0.025；t=-2.896，P=0.004）。ROC曲线显示，PI为1.05时，PI诊断症状性SVD的敏感度为37.9%，特异度为78.7%，曲线下面积为0.590；PI为1.10时，PI诊断症状性SVD的敏感度为22.6%，特异度为82.5%，曲线下面积分别为0.534。

症状性SVD组患者PI高于无症状性组SVD患者，但作为TCD对SVD的早期筛查指标可能缺乏敏感性。

To investigate the changes of intracranial hemodynamics of symptomatic and asymptomatic in patients with the small vessel disease (SVD), to find the cut off value for the diagnosis of SVD by TCD.

Form June 2013 to December 2014, a total of 279 SVD patients were recruited confirmed by magnetic resonance imaging (MRI) in the Second Clinical Hospital of Guangzhou University of Traditional Chinese Medicine. All patients underwent magnetic resonance angiography (MRA), color Doppler ultrasound and TCD examination. The white matter lesions, number of infarcts and hemodynamic parameters were recorded. The cerebral vascular risk factors, stroke number, degree of cerebral white matter lesions and hemodynamic parameters were compared between symptomatic and asymptomatic in patients with SVD. The sensitivity and specificity of pulsatility index (PI) in the diagnosis of SVD were calculated, and the receiver operating characteristic (ROC) curve was plotted.

There was statistically difference in degree of white matter lesion between the asymptomatic and symptomatic group (P<0.05). The degree of leukoaraiosis in asymptomatic SVD group was mainly grade 0~1 accounting for 34.6% (28/81) and 35.8% (29/81) respectively, and grade 3~4 accounting for 14.8% (12/81). In symptomatic SVD group, grade 0 accounted for 15.7% (31/198), grade 1~3 for 29.8% (59/198), 29.3% (58/198) and 25.3% (50/198), respectively. The proportion of leukoaraiosis with grade 0 in asymptomatic SVD was higher than in symptomatic group, while the grade 2~3 was lower than that in symptomatic SVD, and the difference was statistically significant (χ²=13.574, P=0.001; χ²=6.423, P=0.040; χ²=8.265; P=0.005). The mean flow velocity of vertebral artery (VA) and basilar artery (BA) in the symptomatic group was lower than that in asymptomatic group [(23.6±7.3) cm/s vs (27.8±7.0) cm/s, (31.9±10.3) cm/s vs (35.3±9.3) cm/s], and the difference was statistically significant (t=4.269, P<0.001; t=2.500, P=0.013). There was no significant difference in mean velocity of anterior cerebral artery (ACA), middle cerebral artery (MCA) and posterior cerebral artery (PCA) between the two groups. PI were higher in patients with symptom group than asymptomatic group (P<0.05). The mean flow velocity of vertebral and basilar artery of symptom group were lower than those in the asymptomatic group (P<0.05). The optimum cut-off values of PI in diagnosing symptomatic SVD were 1.05 and 1.10, and their sensitivity, specificity and area under the ROC curve was 37.9%, 78.7%, 0.590 and 22.6%, 82.5%, 0.534 respectively.

It may be lack of sensitivity to screen SVD by TCD, although the PI were higher in patients with the symptomatic SVD than the asymptomatic SVD.