Carotid Artery Pseudo-Occlusion

Carotid artery pseudo-occlusion (CAPO), also known as preocclusive stenosis, the carotid slim sign, and the carotid string sign, refers to incomplete ICA occlusion and may be misdiagnosed at angiography as complete occlusion. The distinction is important because while CAPO carries a pretty high stroke risk (~25% within three years), complete internal carotid artery occlusion has a relatively benign prognosis.

The string sign is a thin, antegrade trickle of contrast material in the internal carotid artery distal to an occlusion. The lumen distal to the occlusion is collapsed, leading to diminished flow.

References

• Berman SS, et al. Distinguishing Carotid Artery Pseudo-Occlusion With Color-Flow Doppler. Stroke. 1995;26:434-438
• Greiner C, et al. Revascularization procedures in internal carotid artery pseudo-occlusion. Acta Neurochir (Wien). 2004 Mar;146(3):237-43;
• Pappas JN. The Angiographic String Sign. Radiology 2002;222:237-238.
• Verlato F, et al. Clinical outcome of patients with internal carotid artery occlusion: a prospective follow-up study. J Vasc Surg. 1995; 32:293–298.