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Microemboli on transcranial Doppler in patients with spontaneous carotid artery dissection
H C Koennecke1, S H Trocio, H Mast
1Department of Neurology, Columbia-Presbyterian Medical Center, New York, NY 10032, USA.
Insights
High-intensity transient signals detected via transcranial Doppler (TCD) sonography indicate microemboli in patients with carotid artery dissection and cerebral ischemia. These signals suggest embolism is a primary stroke cause in dissection cases.
Area of Science:
- Neurology
- Vascular Ultrasound
- Cerebrovascular Disease
Background:
- High-intensity transient signals (HITS) on transcranial Doppler (TCD) sonography typically indicate atherosclerotic stenosis.
- Limited data exist on HITS detection in spontaneous carotid artery dissection (SCAD).
Purpose of the Study:
- To investigate the presence and significance of HITS in patients with SCAD.
- To correlate HITS detection with clinical presentation, specifically cerebral ischemia.
Main Methods:
- Six patients with SCAD (confirmed by MRI and duplex sonography) underwent simultaneous TCD monitoring of both middle cerebral arteries for 30 minutes.
- Clinical data, including presence of cerebral ischemia, were recorded.
Main Results:
- HITS were detected in the middle cerebral artery ipsilateral to the dissection in 3 of 4 patients with cerebral ischemia.
- No HITS were observed in patients without cerebral ischemia or on the contralateral side.
- Absence of contralateral HITS suggests localized embolic events.
Conclusions:
- Microemboli, indicated by HITS, can be detected distally from dissected carotid arteries.
- Embolism is a likely major cause of stroke in SCAD patients.
- HITS appear more prevalent in SCAD patients experiencing cerebral ischemia.
Abstract:
High-intensity transient signals on transcranial Doppler sonography (TCD) are associated with atherosclerotic stenosis of the internal carotid artery. Few data exist regarding the detection of high-intensity transient signals in dissected carotid arteries. In the present study, 6 patients with spontaneous carotid dissection, defined by magnetic resonance techniques and duplex sonography, were examined by TCD. Both middle cerebral arteries were monitored simultaneously for 30 minutes. Four of the patients had ipsilateral cerebral ischemia, while 2 presented with other symptoms. High-intensity transient signals were detected in the middle cerebral artery ipsilateral to the dissection in 3 of the 4 patients with cerebral ischemia and in none of the patients with other presenting symptoms. No microemboli were found contralateral to the dissected arteries. Microemboli can be detected distally from dissected carotid arteries. The present findings support the assumption that embolism is a major cause of stroke in patients with carotid dissection, and suggest that high-intensity transient signals are more common among patients with cerebral ischemia secondary to dissection.