Microemboli on transcranial Doppler in patients with spontaneous carotid artery dissection.

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.