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Cerebral vessel stenosis in sickle cell disease: criteria for detection by transcranial Doppler
R J Adams1, F T Nichols, R Aaslid
1Department of Neurology, Medical College of Georgia, Augusta 30912.
Insights
Transcranial Doppler (TCD) can help identify stroke risk in sickle cell disease (Hb SS) patients. Velocities over 190 cm/s in major cerebral arteries strongly suggest stenosis, aiding stroke prevention strategies.
Area of Science:
- Neurology
- Hematology
- Medical Imaging
Background:
- Ischemic stroke is a significant complication in sickle cell disease (Hb SS).
- Intracranial large vessel stenosis, particularly in the circle of Willis, is often implicated in stroke occurrence.
- Transcranial Doppler (TCD) offers a non-invasive method to assess intracranial arterial flow dynamics.
Purpose of the Study:
- To establish criteria using TCD for detecting intracranial stenotic lesions.
- To identify patients with Hb SS who are at higher risk for stroke.
- To correlate TCD flow velocities with angiographically confirmed stenosis.
Main Methods:
- Prospective study involving Hb SS patients.
- Comparison of TCD findings between patients with and without stroke.
- Correlation of TCD velocities with cerebral angiography results in a subset of patients.
Main Results:
- Mean flow velocities >190 cm/s in the middle cerebral (MCA), anterior cerebral (ACA), or internal carotid (ICA) arteries strongly indicate focal stenosis.
- Velocities between 150-190 cm/s in MCA or ACA suggest abnormality but are not diagnostic of stenosis.
- Velocities ≤150 cm/s may be influenced by factors like low hematocrit or young age and are not definitive for stenosis.
Conclusions:
- TCD can be a valuable tool for identifying stroke risk in Hb SS patients by detecting intracranial stenosis.
- Specific velocity thresholds in TCD can help differentiate between normal flow, potential abnormalities, and likely stenosis.
- Further research may refine TCD criteria for more precise diagnosis of stenosis in this population.
Abstract:
Ischemic stroke is a common and disabling complication of sickle cell disease (Hb SS). Most infarctions occur in the presence of intracranial stenotic lesions of the large vessels of the circle of Willis. Transcranial Doppler (TCD), by measuring flow velocity in these arterial segments, can detect focal stenosis on the basis of elevated flow velocity. We report the preliminary results of a prospective study to develop criteria for detection of stenotic lesions based on TCD and identification of patients with Hb SS at risk for stroke. Comparing the TCD findings from six patients with lesions demonstrated by angiography to those from 115 Hb SS children without stroke, we conclude: (a) middle cerebral (MCA), anterior cerebral (ACA), or internal carotid (ICA) artery mean velocities greater than 190 cm/s strongly suggest focal stenosis; (b) MCA or ACA mean velocities of 150 to 190 cm/s suggest abnormality but at present cannot be considered diagnostic of stenosis; (c) mean velocities up to 150 cm/s are possibly due to the effects of low hematocrit and/or young age, and cannot as yet be distinguished from velocity elevations due to vessel stenosis.