Key result
Internal carotid artery stenosis linked to impaired cerebral vascular reactivity regardless of symptom status.
Why the study?
It was hypothesized that symptomatic versus asymptomatic CAS patients would exhibit differences in autoregulatory function and inter-hemispheric blood flow, and that an anatomically compromised circle of Willis would associate with impaired compensation.
Does common carotid artery compression reveal differences in cerebral autoregulatory function and inter-hemispheric blood flow between older adults with symptomatic versus asymptomatic internal carotid artery stenosis?
Observational (n=51)
No
Does common carotid artery compression reveal differences in cerebral autoregulatory function and inter-hemispheric blood flow between older adults with symptomatic versus asymptomatic internal carotid artery stenosis?
Absolute Event Rate: 40% vs 35%
p-value: p=0.76
Transcranial Doppler assessment of transient hyperemic response reveals impaired cerebral vascular reactivity in patients with severe carotid artery stenosis, though it does not differentiate between symptomatic and asymptomatic presentations.
Carotid stenosis impairs reactivity without distinguishing symptomatic status; leaves open whether reactivity testing informs prognosis or management.
Unhealthy vascular aging promotes atherogenesis, which may lead to significant internal carotid artery stenosis (CAS) in 5 to 7.5% of older adults. The pathogenic factors that promote accelerated vascular aging and CAS also affect the downstream portion of the cerebral microcirculation in these patients. Primary treatments of significant CAS are eversion endarterectomy or endarterectomy with patch plasty. Factors that determine adequate hemodynamic compensation and thereby the clinical consequences of CAS as well as medical and surgical complications of carotid reconstruction surgery likely involve the anatomy of the circle of Willis (CoW), the magnitude of compensatory inter-hemispheric blood flow, and the effectiveness of cerebral microcirculatory blood flow autoregulation. This study aimed to test two hypotheses based on this theory. First, we hypothesized that patients with symptomatic and asymptomatic CAS would exhibit differences in autoregulatory function and inter-hemispheric blood flow. Second, we predicted that anatomically compromised CoW would associate with impaired inter-hemispheric blood flow compensation. We enrolled older adults with symptomatic or asymptomatic internal CAS (>70% NASCET criteria; n = 46) and assessed CoW integrity by CT angiography. We evaluated transient hyperemic responses in the middle cerebral arteries (MCA) after common carotid artery compression (CCC; 10 s) by transcranial Doppler sonography (TCD). We compared parameters reflecting autoregulatory function (e.g., transient hyperemic response ratio [THRR], return to baseline time [RTB], changes of vascular resistance) and inter-hemispheric blood flow (residual blood flow velocity). Our findings revealed that CAS was associated with impaired cerebral vascular reactivity. However, we did not observe significant differences in autoregulatory function or inter-hemispheric blood flow between patients with symptomatic and asymptomatic CAS. Moreover, anatomically compromised CoW did not significantly affect these parameters. Notably, we observed an inverse correlation between RTB and THRR, and 49% of CAS patients exhibited a delayed THRR, which associated with decreased inter-hemispheric blood flow. Future studies should investigate how TCD-based evaluation of autoregulatory function and inter-hemispheric blood flow can be used to optimize surgical techniques and patient selection for internal carotid artery revascularization.
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Magyar-Stang et al. (2023) conducted an observational in Internal carotid artery stenosis (CAS) (n=51). Common carotid artery compression (CCC) test vs. Asymptomatic CAS patients and healthy controls was evaluated on Impaired vasoreactivity (THRR < 10%) (p=0.76). Internal carotid artery stenosis was associated with impaired cerebral vascular reactivity compared to controls, but no significant differences in autoregulatory function were observed between symptomatic and asymptomatic patients.
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