Anomalous Retropharygeal Carotid Arteries

This axial CT shows internal and external carotid arteries in a retropharyngeal location bilaterally. A coronal reformat shows the medial looping of the vessels well.
An uncommon anomaly of the course of the carotid arteries, tortuosity with medial looping into the retropharyngeal space may be congenital (possibly due to failure of complete descent of the dorsal aortic arch), and has been described in children. Atheroma-induced tortuosity may contribute to the anomaly in older patients. Failure to identify this anomaly may lead to transpharyngeal biopsy of the retropharyngeal “mass”, with potentially catastrophic consequences. The anomaly should be equally well shown with contrast-enhanced CT, MR angiography, or digital subtraction angiography. The finding is usually incidental, and should always be reported.
Other causes of widening or apparent widening of the retropharyngeal (or prevertebral) soft tissues include abscess (pyogenic or tuberculous), haematoma (often secondary to cervical spine fracture), tumour (carcinoma, lymphoma), swallowing, crying, or neck flexion (particularly a problem in children).
References:
1. Palacios E, Kirsch D, Rojas R. Anomalous course of the carotid arteries in the retropharyngeal space poses a surgical risk. ENT Journal June 2005
2. Fix TJ, Daffner RH, Deeb ZL. Carotid transposition: Another cause of wide retropharyngeal soft tissues. AJR 1996;167:1305-7.
Credit: Dr Laughlin Dawes
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