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Intermittent drop in blood flow velocity in the internal carotid artery and its branches
Cirus Samii1, Rolf R Diehl, Peter Berlit
1Department of Neurology with Clinical Neurophysiology, Alfried Krupp Hospital, Alfried Krupp Street 21, D-45117 Essen, Germany.
Insights
Extracranial and transcranial Doppler sonography can monitor cerebrovascular events. An unusual intermittent blood flow drop in carotid siphon stenosis, potentially due to a shifting thrombus, was observed without symptoms.
Area of Science:
- Neurology
- Vascular Ultrasound
- Medical Imaging
Background:
- Extracranial and transcranial Doppler sonography (TCD) are crucial for assessing cerebrovascular diseases.
- These techniques monitor hemodynamic and embolic events in patients.
Observation:
- An unusual hemodynamic phenomenon was observed in a patient with asymptomatic intracranial carotid siphon stenosis.
- Transcritical Doppler sonography showed a sudden, intermittent drop in blood flow velocity in both prestenotic and poststenotic segments.
Findings:
- Angiography confirmed left internal carotid artery siphon stenosis.
- Cardiac hemodynamic parameters remained unaffected during the observed flow drops.
- Embolic signals were exclusively detected in poststenotic vessels.
Implications:
- The findings suggest a novel mechanism for intermittent vessel occlusion in carotid siphon stenosis.
- This phenomenon may be linked to the reversible displacement of an intraluminal thrombus, influenced by the cardiac cycle.
- TCD may detect subtle hemodynamic changes indicative of embolic risk even in asymptomatic stenosis.
Abstract:
Extracranial Doppler sonography and transcranial Doppler sonography (TCD) allow the assessment and monitoring of hemodynamic and embolic events in cerebrovascular diseases. We describe an unusual hemodynamic phenomenon in a patient with intracranial carotid siphon stenosis and no clinical symptoms of stenosis. TCD examination suggested and angiography confirmed stenosis of the left internal carotid artery siphon. TCD examination revealed a sudden, intermittent drop in blood flow velocity in both the prestenotic and poststenotic segments of the internal carotid artery, whereas cardiac hemodynamic parameters were unaffected. Embolic signals were detected in the poststenotic vessels only. We speculate that such sonographic findings may be caused by intermittent vessel occlusions due to the reversible displacement of an intraluminal thrombus in relation to the cardiac cycle.