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Logo of jnnpsycJournal of Neurology, Neurosurgery and PsychiatryVisit this articleSubmit a manuscriptReceive email alertsContact usBMJ
J Neurol Neurosurg Psychiatry. 2007 November; 78(11): 1270.
PMCID: PMC2117590

The sonographic pitfall of carotid collateralisation via the vasa vasorum

A 52‐year‐old man with obesity, type 2 diabetes mellitus and hypertension was admitted because of sudden onset of left hemiparesis and somnolence. Brain MRI disclosed a recent right thalamic stroke and multiple encephaloclastic lesions, suggestive of vascular sequelae. Carotid ultrasound demonstrated occlusion of the right internal carotid artery (ICA) and residual flow in the periphery of the left ICA lumen (fig 1A, BB).). Subocclusive stenosis was suspected. Carotid arteriography confirmed atherosclerotic occlusion of both bulbar ICAs. On the left side, however, filiform collateralisation with a spiral configuration was seen, extending from the ICA bulb to the cavernous segment (fig 1C1C).). The patient was offered medical treatment.

figure jn118349.f1
Figure 1 (A) Colour coded duplex ultrasonography, transverse section, 1 cm above the carotid bifurcation, shows the occluded internal carotid artery (ICA) lumen (*) and a thin segment of flow within its wall (black arrows), outlining ...

Collateralisation through the vasa vasorum of an atheromatous occlusion of the ICA is a rare finding. Growth of collaterals in the wall of the vessel is a slow process, stimulated by the proangiogenic properties of the plaque.1

Differentiating carotid occlusion with collateralisation from pre‐occlusive stenosis is of the utmost importance because there is no benefit of endarterectomy or angioplasty in the first situation.

Carotid ultrasound is a reliable method in the assessment of ICA stenosis and occlusion. However, the findings of residual flow with normal velocities and waveform may erroneously be attributed to subocclusive carotid disease2 in which it has been shown that velocity measurements start to decrease. Therefore, corroboration with arteriography is recommended. High resolution transverse colour coded sections showing segments of flow within the ICA wall itself, outlining the circumference of the vessel may be a clue to the correct diagnosis.


Competing interests: None.


1. Bo W J, Mercuri M, Tucker R. et al The human carotid atherosclerotic plaque stimulates angiogenesis on the chick chorioallantoic membrane. Atherosclerosis 1992. 9471–78.78 [PubMed]
2. Kriegshauser J S, Patel M D, Nelson K D. et al Carotid pseudostring sign from vasa vasorum collaterals. J Ultrasound Med 2003. 22959–963.963 [PubMed]

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