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Source of cerebral microembolic signals in occlusion of the internal carotid artery
A Delcker1, H C Diener, H Wilhelm
1Department of Neurology, University of Essen, Germany.
Background And Purpose:
There are several possible sources of cerebral embolic ischaemia distal to an occlusion of the internal carotid artery (ICA). Our aim was to identify the source of microembolic signals in the ipsilateral middle cerebral artery (MCA) by taking simultaneous bitemporal transcranial Doppler ultrasound recordings of the ipsilateral MCA and the contralateral ACA to find the route of potential microembolic material to MCA.
Subjects And Methods:
The study group consisted of 38 patients with an occlusion of the ICA. With extracranial duplex sonography (ACUSON 128 XP; 7 MHz), performed by an experienced sonographer, the echo intensity and echo structure of the occluded ICA in the extracranial part (proximal) were classified as homogeneous or inhomogeneous. In addition, affected segments of the ipsilateral and contralateral carotid artery with arteriosclerotic vessel walls were compared. Microembolic signals were recorded with transcranial Doppler (TCD) monitoring. The microemboli counts in the MCA and ACA were added to the sum scores.
Results:
The number of affected segments of the carotid artery on the ipsilateral (the bifurcation, the external or common carotid artery) and contralateral side of occluded ICA were equally distributed. In ipsilateral MCA 3.1, 7.1 microemboli (average mean, SD) with a range of between 0 and 34 were counted, in the contralateral ACA 0.3, 0.6 (range of between 0 and 2). Regression analysis confirmed the non-predictability of the microemboli variance on the ipsilateral side of the occlusion from the variance on the contralateral side (multiple r: 0.024). We found no significant correlation between the echo intensity or echo structure of the occluded artery and an increased rate of microemboli in the ipsilateral MCA.
Conclusions:
Our results indicate a predominantly ipsilateral source for cerebral microemboli in ICA occlusion. The rate of cerebral microembolic signals was not influenced by the echo structure and echo intensity of the occluded ICA.
Insights
In internal carotid artery (ICA) occlusion, microembolic signals in the middle cerebral artery (MCA) predominantly originate from the ipsilateral side. The characteristics of the occluded ICA did not influence the rate of these cerebral microemboli.
Area of Science:
- Neurology
- Vascular Neurology
- Cerebrovascular Disease
Background:
- Cerebral embolic ischemia distal to internal carotid artery (ICA) occlusion has multiple potential sources.
- Identifying the precise origin of microembolic signals is crucial for understanding stroke mechanisms.
Purpose of the Study:
- To determine the source of microembolic signals in the ipsilateral middle cerebral artery (MCA) in patients with ICA occlusion.
- To investigate the relationship between microembolic signals and the characteristics of the occluded ICA.
Main Methods:
- Simultaneous bitemporal transcranial Doppler (TCD) ultrasound recordings of the ipsilateral MCA and contralateral anterior cerebral artery (ACA).
- Extracranial duplex sonography to classify the echo intensity and structure of the occluded ICA.
- Comparison of arteriosclerotic changes in ipsilateral and contralateral carotid arteries.
Main Results:
- Microembolic signals were predominantly detected in the ipsilateral MCA (mean 3.1-7.1 signals) compared to the contralateral ACA (mean 0.3-0.6 signals).
- No significant correlation was found between the echo intensity or structure of the occluded ICA and the rate of ipsilateral MCA microemboli.
- Microemboli counts in the ipsilateral MCA were not predictable from counts in the contralateral ACA.
Conclusions:
- Cerebral microemboli in ICA occlusion primarily originate from ipsilateral sources.
- The echo characteristics of the occluded ICA do not influence the generation of cerebral microembolic signals.