Internal carotid artery dissections: duplex ultrasound imaging.

Duplex ultrasound findings in seven patients (eight vessels) demonstrating extracranial internal carotid artery (ICA) dissections are presented. The two-dimensional (2D) sonographic findings of ICA dissection consisted of three categories: (1) normal, (2) luminal flap with or without thrombus formation, and (3) hypoechoic thrombus with or without lumen narrowing. The Doppler ultrasound waveforms were variable. In the common carotid artery (CCA) these included (1) normal, (2) resistive, damped, or biphasic CCA waveforms, and (3) positive temporal artery tap in the mid-CCA. In the ICA, the appearances included (1) normal, (2) damped, resistive, or biphasic waveforms, (3) absent flow, and (4) high velocity flow. Although these appearances are nonspecific, the finding of some of these duplex ultrasound waveforms in the appropriate clinical setting suggests a diagnosis of extracranial internal carotid artery dissection.