Correlation Study On Vertebral Artery Stenosis And Cerebrovascular Reactivity Of Posterior Circulation

Part ⅠCerebrovascular reactivity evaluation in the posterior circulation infarction patients without carotid and cerebrovascular stenosisObjective:We evaluated the hemodynamic features in patients without stenosis of cerebral artery by assessing cerebrovascular reactivity in middle cerebral artery (MCVR) and vertebral arteries (VCVR), in order to draw the difference between MCVR and VCVR in predicts posterior circulation infarction (PCI).Methods:We investigated 27 patients with posterior circulation infarction (PCI group). Healthy age-matched subjects during the study period were included (Controls). Transcranial Doppler (TCD) combined with CO2 inhalation test was done to assess and compare the MCVR and VCVR in all subjects.Results:Compared with controls, a significant impairment of the MCVR (left and right) was observed (25.96±15.90% vs 34.63±8.60%,26.40±14.54% vs 34.49±9.08%, P<0.05); Thus, the VCVR showed a gradual impairment but did not reach statistical significance (P> 0.05). Multivariate linear regression analysis adjusting for age, hypertension and diabetes et al revealed diabetes as an independent determinant of reduced MCVR (p=-0.116, P= 0.035).Conclusions:Impaired MCVR may be an independent predictor of posterior circulation stroke, but not VCVR, suggesting an independent cerebral vascular reserve capacity of the posterior circulation.Part ⅡCorrelation between severity of vertebral stenosis and cerebrovascular reactivityObjective:Cerebrovascular reactivity (CVR) is a commonly accepted indicator reflecting the hemodynamic reserve of the cerebral circulation. Previous studies have evaluated the correlation between MCVR and stenosis of internal carotid artery (ICA) or MCA, whereas the relationship between the degree of vertebral artery (VA) stenosis and VCVR is not well studied. We aimed to investigate the association between CVR and the stenosis severity of VA.Methods:Hemodynamic features by assessing VCVR and MCVR of consecutive patients with or without VA stenosis confirmed by the digital substraction angiography (DSA) were evaluated with transcranial Doppler (TCD) and the CO2 inhalation test. The degree of the stenosis of the extracranial or intracranial VA was calculated with the NASCET method or the WASID technique respectively.Results:VCVR on the side of VA stenosis is significantly lower than contralateral side (28.82± 12.91% vs 31.52±14.09%, P< 0.05), no differences in MCVR was found (27.07±15.77%vs 29.12±17.16%, P> 0.05). Decrease of VCVR was well correlated with the degree of VA stenosis (correlation coefficient=-0.470, P< 0.01). Multiple linear regression analysis revealed VA stenosis and diabetes mellitus as an independent determinant of reduced VCVR (P=-0.432, P= 0.009, p=-0.405, P= 0.013).Conclusion:In this study, VCVR but not MCVR in the stenotic side was significantly conversely correlated with degree of VA stenosis, suggesting an independent CVR capacity of the posterior circulation.Part IIIEffect of vertebral artery stenting on cerebrovascular reactivityObjective:Vertebral artery stenting (VAS) has become an important method of treating severe VA stenosis. But whether it is the choice of operation indications or assess the curative effect of postoperative, we assessing the degree of stenosis confined radiological and clinical symptoms currently. In our study, we aimed to investigate VCVR changes after VAS.Methods:24 symptomatic patients with VA stenosis who received VAS treatment were selected as the operated group.22 hospitalized posterior stroke patients without VA stenosis or VA stenosis<50% at the same period served as the control group. Transcranial Doppler ultrasonography (TCD) combined with CO2 inhalation test was used to assess the changes of VCVR before and after VAS.Results:Compared with the control group, preoperative VCVR of the operated and contralateral sides significantly reduced in the operated group (25.37±9.42% vs 31.51± 10.59%,28.84±7.07% vs 35.98±15.48%, P< 0.05); the operated side VCVR was significantly impaired than the contralateral side (25.37±9.42% vs 28.84±7.07%, P< 0.05). After stenting, both the operated and contralateral VCVR increased, but did not reach statistical significance.Conclusions:VAS may not improve compromised VCVR on both the operated and contralateral sides in the short term. Further studies with a longer follow-up period are needed to confirm our findings.