Oscillating thrombi in bilateral extracranial internal carotid arteries demonstrated on ultrasonography: two autopsy cases of cardioembolic stroke.

We herein report two autopsy cases of severe cardioembolic stroke with oscillating thrombi in the bilateral extracranial internal carotid arteries (ICAs) demonstrated on carotid ultrasonography performed on admission. An autopsy study of case 1 conducted on the third hospital day revealed no thrombi, while that of case 2 conducted on the 42nd hospital day revealed red thrombi in the extracranial ICAs. Our postmortem studies confirm that oscillating thrombi may be seen in the region of blood stasis caused by occlusion of the distal portion of the ICA, thus reflecting a pre-state of thrombus formation.