Absent middle cerebral artery signal in transcranial color-coded sonography: a reliable indicator of occlusion?
Absent MCA stem signal may result from MCA stem occlusion/tight stenosis and tight stenosis of ipsilateral carotid arteries, and has a limited value in detecting MCA stem occlusion. TCCS can be useful in identifying nonoccluded MCA stem, and cerebral angiography is necessary to confirm MCA stem occlusion.
These results suggest a possible reason for the poorer response to laser treatment seen in limb CMs: since cutaneous blood flow is a product of the blood flow velocity and hemoglobin concentration, malformations with lower blood perfusion would have less chromophore available and therefore be less suitable for laser destruction.