椎动脉发育不良患者后循环血流量和管壁剪切力的变化及其意义

Changes and significance of the posterior circulation blood flow and wall shear stress in patients with vertebral artery hypoplasia

目的应用经颅多普勒超声(TCD)评估椎动脉发育不良(VAH)患者后循环血流量、管壁剪切力等参数变化,了解VAH促发后循环梗死(PCI)的可能机制。方法前瞻性连续入组2014年10月至2016年1月郑州人民医院神经内科住院的可疑为血管性眩晕患者261例,采用眩晕症状量表(VSS)评价眩晕严重程度。患者均于入院3 d内完成TCD和高场强MR检查[T1、T2加权成像,液体衰减反转恢复(FLAIR),扩散加权成像(DWI),MR血管成像(MRA),对比剂增强MRA(CEMRA)],并根据椎动脉直径大小结合VAH诊断标准,分为VAH组和非VAH组,分析两组间后循环血流速度[收缩期血流速度(V_s)、舒张期血流速度(V_d)、平均血流速度(V_m)]、搏动指数(PI)、阻力指数(RI)、平均血流量(MFV)及管壁剪切力(WSS)的差异。应用SPSS19. 0进行统计学分析,计量资料组内或组间比较分别采用配对、独立样本t检验或非参数秩和检验,计数资料组间比较采用χ~2检验。结果 261例患者中,VAH患者78例(29. 9%),合并基底动脉发育不良26例,合并胚胎型大脑后动脉37例,发生PCI 48例(18. 4%)。与非VAH组比较,VAH组患者眩晕程度更重[3(2,4)级比3(1,3)级,Z=2. 09],后循环梗死发生率明显升高[25. 6%(20/78)比13. 5%(28/183),χ~2=5. 34],差异均有统计学意义(均P <0. 05)。VAH组发育不良侧椎动脉V_s、V_d、V_m、MFV及WSS分别为(30±8)、(8±4)、(17±5) cm/s和(33±17) ml/min、(10±3) dyn/cm^2,较同组对侧和非VAH组左右侧明显减低(均P <0. 05),VAH组正常侧椎动脉MFV[(175±82) ml/min]较非VAH组左右侧代偿性轻度升高,差异有统计学意义(P <0. 05);双侧椎动脉总MFV较非VAH组明显降低[(207±98) ml/min比(291±112) ml/min,P <0. 05]。与非VAH组比较,VAH组基底动脉V_s、V_d、V_m及MFV、WSS降低[分别为(56±21) cm/s比(69±19) cm/s、(20±10) cm/s比(27±10) cm/s、(34±14) cm/s比(44±14) cm/s、(128±77) ml/min比(178±78) ml/min、(16±8) dyn/cm^2比(19±7) dyn/cm^2,t值分别为-4. 85、-5. 10、-5. 23、-4. 45、-3. 58],RI增高(0. 7±0. 2比0. 6±0. 1,t=4. 07),PI降低(0. 9±0. 2比1. 0±0. 3,t=-2. 78),差异均有统计学意义(均P <0. 05)。VAH组发育不良侧大脑后动脉的TCD各项参数与对侧及非VAH组左右侧比较,差异均无统计学意义(均P> 0. 05)。结论眩晕合并血管危险因素的患者VAH发生率较高,VAH影响后循环血流动力学,可能与PCI发生有关。

Objectives To evaluate the parameter changes of posterior circulation blood flow and wall shear stress in patients with vertebral artery hypoplasia(VAH)and to understand the possible mechanisms of VAH-induced posterior circulation infarction(PCI).Methods A total of 261 consecutive patients with suspected vascular vertigo admitted to the Department of Neurology,People's Hospital of Zhengzhou from October 2014 to January 2016 were enrolled.The vertigo symptom scale(VSS)was used to evaluate the severity of vertigo.All patients completed TCD and high field strength MR examination within 3 d of admission(T1,T2 weighted imaging,fluid attenuation inversion recovery[FLAIR],diffusion-weighted imaging[DWI],MR angiography[MRA],contrast-enhanced MRA[CEMRA]),and according to the diameter of the vertebral artery combined with the diagnostic criteria of VAH,they were divided into VAH group and non-VAH group,Posterior circulation blood flow velocity(systolic velocity[Vs],diastolic velocity[Vd],mean velocity[Vm]),pulsatility index(PI),resistance index(RI),mean flow velocity(MFV),and wall shear stress(WSS)between the two group were analyzed.The paired or independent sample t test,Mann-Whitney U test and the 2 test were conducted with SPSS19.0 for intra-group or inter-group comparisons.Results Of 261 patients,78(29.9%)had VAH,26 were complicated with basilar artery hypoplasia,37 were complicated with fetal type posterior circle of Willis,and posterior circulation infarction occurred in 48(18.4%).Compared with the non-VAH group,the degree of vertigo of patients was more severe in the VAH group(3[2,4]vs.3[1,3],Z=2.29),and the incidence of posterior circulation infarction was significantly increased(25.6%[20/78]vs.13.5%(28/183),χ2=5.34).The differences were statistically significant(all P<0.05).The Vs,Vd,Vm,MFV,and WSS of the dysplasia sides of the VAH group were 30±8,8±4,17±5 cm/s and 33±17 ml/min,10±3 dyn/cm2,respectively,compared with the contralateral side of the same group and the non-VAH group,the left and right sides were significantly reduced(all P<0.05).The vertebral artery MFV on the normal side(175±82ml/min)in the VAH group was compensatorily mildly increased on the left and right sides of the non-VAH group,but the total MFV of bilateral vertebral arteries was significantly lower than that of the non-VAH group(207±98 ml/min vs.291±112 ml/min,P<0.05).Compared with the non-VAH group,the Vs,Vd,Vm,MFV,and WSS of the basilar artery in the VAH group were decreased(56±21 cm/s vs.69±19 cm/s,20±10 cm/s vs.27±10)cm/s,34±14 cm/s vs.44±14 cm/s,128±77 ml/min vs.178±78 ml/min,16±8 dyn/cm2 vs.19±7 dyn/cm2,respectively,t=-4.85,-5.10,-5.23,-4.45 and-3.58 respectively,RI was increased(0.7±0.2 vs.0.6±0.1,t=4.07),and PI was decreased(0.9±0.2 vs.1.0±0.3,t=-2.78).The differences were statistically significant(all P<0.05).There were no significant differences in each TCD parameters of posterior cerebral artery on the dysplastic side between the contralateral side and the left and right sides of the non-VAH group(all P>0.05).Conclusions The incidence of VAH was higher in patients with vertigo and vascular risk factors.VAH affected the posterior circulation hemodynamics,which might be associated with the occurrence of PCI.