Dynamic Cerebral Autoregulation In Healthy Adults And Patients With Unilateral Middle Cerebral Artery Stenosis

Objective:We aimed to assess the dynamic cerebral autoregulation (dCA) in healthy adultsand patients with unilateral middle cerebral artery (MCA) stenosis. To see1) whetherthe dCA was gender-related and if the dCA between the anterior circulation andposterior circulation was different.2) whether the dCA can predict the risk of stenosisipsilateral stroke.3)whether and how the acute ischemic affected the dCA.Methods:Study1:100healthy adults (34.35±8.57years old;50males) were enrolled.Study2:Fifty-seven patients with asymptomatic mild, moderate, severe unilateralMCA stenosis and eight patients with symptomatic severe unilateral MCA stenosisdiagnosed by transcranial Doppler sonography (TCD) were enrolled. Twenty-fourhealthy volunteers were served as controls. Non-invasive continuous cerebral bloodflow velocityusing TCD on MCA bilaterally and arterial blood pressure wererecorded simultaneously from each subject in supine position. In study1, among of100healthy adults,30participants who were aging20to30years old were chosenonce again for the comparison between anterior and posterior circulations (located theTCD probe on the left MCA and right posterior cerebral artery). Transfer functionanalysis (TFA) was applied to derive autoregulatory parameters [phase difference(PD) and gain].Results:1. The overall PD between males and females (54.54±25.04°vs58.14±26.47°)was no difference. There was also no difference between groups and two sides ineach group in gain (0.80±0.34cm/s/mmHg vs0.71±0.29cm/s/mmHg, P=0.07). Therewas a tendency that PD and gain were lower in PCA than MCA (44.60±26.34°vs53.96±25.70;0.64±0.30cm/s/mmHg vs0.75±0.32cm/s/mmHg, respectively). But thedifference was not significant (P=0.20,0.20, respectively). 2. PD in the severe stenosis was significantly lower than the control group(60.39±19.30°): the asymptomatic severe stenosis impaired ipsilaterally(28.94±27.34°,P＜0.001), and the symptomatic severe stenosis impaired bilaterally(ipsilateral side13.74±19.21°, P＜0.001；contralateral side19.68±14.50°, P=0.006).Whereas the PD in the mild and moderate stenosis groups had no significantdifference with the controls (44.49±27.93°;48.65±25.49°, separately). The gain inmild and moderate groups were higher than the controls (1.00±0.58cm/s/mmHg vs0.88±0.34cm/s/mmHg,1.02±0.59cm/s/mmHg vs0.88±0.34cm/s/mmHg), but thedifferences had no significant. Gain in the severe stenosis group were significantlylower than the control group: the asymptomatic severe stenosis group was lowerbilaterally (0.56±0.32cm/s/mmHg, P=0.03;0.60±0.32cm/s/mmHg, P=0.018,separately), and the symptomatic severe group was lower ipsilateral (the contralaeralside)(0.53±0.43cm/s/mmHg, P=0.018). The patients were followed-up for1year,there was no stroke or transient ischemic attack (TIA) in all groups.Conclusions:1. There were no gender-related differences of dCA in PD and gain; There was atendency but not significant that the PD and gain were lower in PCA than MCA.2. In the unilateral asymptomatic stenosis, only the dCA of the severe stenosiswas ipsilaterally impaired.3. Acute stroke may aggravate the impaired dCA, even spread to thecontralateral side.