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Cerebral microembolism in symptomatic and asymptomatic high-grade internal carotid artery stenosis
M Siebler1, A Kleinschmidt, M Sitzer
1Department of Neurology, Heinrich-Heine-University, Düsseldorf, Germany.
Insights
Transcranial Doppler (TCD) ultrasonography detects microemboli in patients with internal carotid artery (ICA) stenosis. A higher rate of these silent events reliably indicates recent ischemic symptoms, suggesting unstable ICA disease.
Area of Science:
- Neurology
- Vascular Medicine
- Medical Imaging
Background:
- High-grade internal carotid artery (ICA) stenosis is a risk factor for ischemic stroke.
- Silent microemboli detected by transcranial Doppler (TCD) may indicate unstable cerebrovascular disease.
Purpose of the Study:
- To investigate the relationship between TCD-detected silent microemboli in the middle cerebral artery and recent ischemic symptoms in patients with high-grade ICA stenosis.
Main Methods:
- Utilized transcranial Doppler (TCD) ultrasonography to monitor for silent microemboli in the middle cerebral artery.
- Compared microembolic event rates in neurologically symptomatic versus asymptomatic patients with matched degrees of ICA stenosis.
Main Results:
- Silent microemboli were significantly more frequent in neurologically symptomatic patients (14/h) compared to asymptomatic patients (0.35/h).
- An individual microembolic event rate of >= 2/h demonstrated a positive predictive value of 0.88 for recent ischemic symptoms.
Conclusions:
- TCD monitoring of silent microemboli provides reliable paraclinical evidence of unstable internal carotid artery (ICA) disease.
- This technique can aid in identifying patients at higher risk for stroke due to carotid stenosis.
Abstract:
Using transcranial Doppler (TCD) ultrasonography in patients with high-grade (> or = 70%) internal carotid artery (ICA) stenosis, we examined the relation between the rate of TCD-detected silent microembolism of the ipsilateral middle cerebral artery and a history of recent (< 121 days) ischemic symptoms attributable to the diseased ICA. In the so-defined neurologically symptomatic group (n = 33 patients), silent microembolic events occurred in 27 subjects (overall mean rate, 14/h +/- 29). Among 56 neurologically asymptomatic patients matched for the degree of ICA stenosis, only nine showed such events (overall mean rate, 0.35/h +/- 1.4). Across all 89 patients studied, an individual microembolic event rate > or = 2/h had a positive predictive value of 0.88 for a history of recent symptoms. Our data suggest that TCD monitoring can provide reliable paraclinical evidence of "unstable ICA disease."