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Cerebral blood flow reserve assessment in symptomatic versus asymptomatic high-grade internal carotid artery stenosis
N Nighoghossian1, P Trouillas, B Philippon
1Department of Neurology Cerebrovascular Disease, Neurological Hospital, Lyon, France.
Insights
Patients with severe carotid stenosis, whether symptomatic or asymptomatic, did not show significantly restricted cerebral blood flow compared to controls. The acetazolamide test for cerebral perfusion reserve may be inconsistent in individual assessments.
Area of Science:
- Neurology
- Vascular Medicine
- Medical Imaging
Background:
- Thromboembolic stroke risk is linked to reduced cerebral blood flow reserve.
- Severe carotid stenosis can compromise blood flow to the brain.
Purpose of the Study:
- To compare hemodynamic restriction in symptomatic vs. asymptomatic carotid stenosis.
- To assess cerebral perfusion reserve in carotid occlusive disease patients versus controls.
Main Methods:
- 133Xe inhalation method and acetazolamide challenge used.
- Compared symptomatic (n=10), asymptomatic (n=10) high-grade carotid stenosis patients, and 10 controls.
- Assessed baseline and post-acetazolamide cerebral blood flow.
Main Results:
- No significant difference in baseline cerebral blood flow between symptomatic, asymptomatic, and control groups.
- Cerebral blood flow increase after acetazolamide was similar across all groups.
- Some individuals in all groups showed no significant increase in cerebral blood flow post-acetazolamide.
Conclusions:
- Hemodynamic factors in thromboembolic ischemia may be subtle in some severe carotid stenosis cases.
- The acetazolamide test's reliability for individual cerebral perfusion reserve assessment is questionable.
Background And Purpose:
Thromboembolic stroke is likely to occur in patients with a restricted cerebral blood flow reserve. Our aims were to determine (1) whether symptomatic patients had any significant hemodynamic restriction ipsilateral to carotid occlusive disease compared with patients whose carotid stenosis is asymptomatic and (2) whether patients with carotid occlusive disease have impaired cerebral perfusion reserve compared with control subjects.
Methods:
We compared cerebral blood flow and collateral capacity using the 133Xe inhalation method and acetazolamide test in symptomatic (n = 10) and asymptomatic (n = 10) patients who had a high-grade internal carotid artery stenosis (range, 70% to 99%). Results were compared with those from 10 healthy control subjects.
Results:
Mean baseline cerebral blood flow was 40.29 +/- 1.38 mL/100 g per minute on the symptomatic side in symptomatic patients versus 45.20 +/- 2.53 mL/100 g per minute on the lesion side in asymptomatic patients (control subjects, 46.91 +/- 2.11 mL/100 g per minute in the right hemisphere versus 46.17 +/- 1.93 mL/100 g per minute in the left). There was no statistical difference between patients in symptomatic and asymptomatic groups versus control subjects (P > .10). Mean cerebral blood flow increase after acetazolamide was in the same range in symptomatic (52.89 +/- 2.54 mL/100 g per minute) and asymptomatic (56.22 +/- 3.35 mL/100 g per minute) patients (P > .10), and no difference was observed regarding control subjects (54.25 +/- 2.94 mL/100 g per minute; P > .10). Three asymptomatic and two symptomatic patients and three control subjects had no significant cerebral blood flow increase after acetazolamide.
Conclusions:
An additional hemodynamic factor in thromboembolic ischemia related to severe unilateral carotid stenosis might be an unusual finding in patients without apparent hemodynamic induction of symptoms. The lack of significant variation in postacetazolamide cerebral blood flow in some patients and control subjects implies that this procedure may be inconsistent in assessing the cerebral perfusion reserve in the individual case.