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Assessment of dynamic cerebral autoregulation in patients with basilar artery stenosis
Xiping Gong1, Jia Liu, Pei Dong
1Department of Neurology, Beijing Tiantan Hospital, affiliated to Capital Medical University, Beijing, China.
Insights
Cerebral autoregulation (CA) is impaired in severe basilar artery stenosis, particularly affecting the posterior cerebral artery (PCA). Reduced phase shift in PCA may indicate poor outcomes after ischemic stroke.
Area of Science:
- Neurology
- Vascular Medicine
- Medical Imaging
Background:
- Cerebral autoregulation (CA) is crucial for maintaining stable brain blood flow.
- Impaired CA is known in carotid and middle cerebral artery stenosis.
- CA in basilar artery (BA) stenosis remains poorly understood.
Purpose of the Study:
- To investigate dynamic CA patterns in patients with BA stenosis.
- To utilize transfer function analysis (TFA) for assessing CA.
- To compare CA between BA stenosis patients and healthy controls.
Main Methods:
- Measured blood flow velocity (CBFV) in PCA and MCA, and mean arterial pressure (ABP).
- Analyzed 25 BA stenosis patients (moderate/severe) and 22 healthy volunteers.
- Employed transfer function analysis (TFA) to derive phase and gain.
Main Results:
- No significant differences in MCA phase shift or gain between groups.
- Significantly decreased PCA phase shift in severe BA stenosis compared to controls and moderate stenosis.
- Increased PCA gain in moderate BA stenosis, decreased in severe BA stenosis.
- Abolished PCA phase shift observed in stroke patients with poor 90-day outcomes.
Conclusions:
- Dynamic CA in the PCA is reduced in severe BA stenosis.
- Impaired CA in PCA is associated with poor outcomes in ischemic stroke patients.
- PCA phase shift may serve as a sensitive indicator of impaired posterior circulation CA.
Background And Aims:
Previous studies have shown impaired cerebral autoregulation (CA) in carotid and middle cerebral artery (MCA) stenosis/occlusion. Little is known about CA in patients with basilar artery (BA) stenosis. We therefore investigated dynamic CA patterns in BA stenosis using transfer function analysis (TFA).
Methods:
We measured spontaneous oscillations of blood flow velocity (CBFV) in the right posterior cerebral artery (PCA), and left MCA and mean arterial pressure (ABP) continuously in 25 patients with BA stenosis (moderate n=16 with 50-69% occlusion and severe n=9 with ≥ 70% occlusion) and 22 healthy volunteers in supine position during 6 circles per minute deep breath. Analysis was based on the 'black-box' model of transfer function deriving phase and gain in both PCA and MCA.
Results:
Though changes of phase shift and gain between the patients and healthy controls were observed in MCA, the differences are however not significant. Phase shift in PCA was significantly decreased in severe stenosis when comparing with healthy controls and moderate stenosis (4.2 ± 34.2° VS 41.1 ± 40.4°, 4.2 ± 34.2° VS 34.2 ± 27.2°, both p<0.05), whilst the gain in PCA is increased for moderate BA stenosis and decreased for severe BA stenosis. Furthermore, we found that phase shift were almost abolished in patients with ischemic stroke who developed unfavorable clinical outcome (mRs>2) on the 90 days after stroke onset.
Conclusion:
Dynamic CA in PCA reduces in patients with severe BA stenosis and those with ischemic stroke who present poor outcome in 90 days after stroke onset. Phase shift might be a sensitive index prompting impaired CA in posterior circulation.
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