Multichannel internal carotid artery: congenital or acquired pattern?

Internal carotid artery (ICA) anomalies are a rare occurrence, being ICA one of the more stable arteries from the embryologic point of view. Nevertheless, duplication and fenestration are not uncommon, even in the cervical segment, but more complex anomalies (e.g. aberrant ICA) are particularly rare.

We are presenting an incidental finding in a patient undergoing ultrasound study of the neck arteries, followed by Computed Tomography Angiography (CTA) and Digital Subtraction Angiography (DSA) finding an anomalous pattern on the left cervical ICA with a multichannel appearance for the whole extracranial course. The patient did not refer any symptom or clinical event and the brain Magnetic Resonance Imaging (MRI) did not show signal changes. ICA embryology was checked in order to find a potential interpretation as anomaly vs. abnormality, considering the embryo stages when the third aortic arch is constituted by several unfused channels and comparing the imaging pattern of the present patients with the already known pathophysiology of ICA fenestration and duplication besides the more complex rete mirabile. Acquired caused were also considered, in particular the pseudo-recanalization of ICA occlusion through vasa vasorum.

The multichannel pattern of the extracranial ICA in the presented case is probably at one end of the range of potential ICA anomalies, although it is not possible to completely exclude an acquired cause.