Anatomical variations of origin of the internal carotid artery: Report of two cases and systematic review of the literature

Abstract

BackgroundAnatomical variations of origin of the internal carotid artery (ICA) are very uncommon and may pose a diagnostic and therapeutic challenge.ObjectiveWe report a case of direct origin of the right ICA from the innominate artery (aplasia of common carotid artery) and a case of duplication of right ICA in healthy patients who performed duplex ultrasound (DUS) for primary cardiovascular prevention screening.MethodsIn both cases, the ultrasound scan was performed both in a transverse plane and on the longitudinal axis, and in one of the two cases, a computed tomography angiography was performed to confirm the diagnosis. A review of the current literature about anatomical variations of origin of carotid arteries was also performed.ResultsThe most frequent congenital anomaly is represented by the aplasia of the CCA, followed by the agenesis and by the duplication of the ICA. In most cases, the anomaly is discovered occasionally and symptoms are aspecific. Diagnosis is usually confirmed through a multimodality imaging approach, including DUS of extracranial carotid arteries, magnetic resonance imaging (MRI), and computed tomographic angiography. In most cases, treatment was conservative, with pharmacological therapy aimed at the symptoms.ConclusionThe recognition of such variations is mandatory, particularly when the patient needs a surgical treatment that may involve the vessel with the anatomical variations.

Keywords: Agenesia; anatomical variations; duplication; internal carotid artery.

Figure 1.

Representative DUS images of CCA agenesis: 1a: two parallel arterial vessels from the base of the neck and throughout the explorable tract; 1b: pulsed Doppler showed a monophasic low-resistance flow which identifies that vessel as the ICA; 1c: pulsed Doppler showed triphasic high-resistance flow which identifies that vessel as the ECA; 1d: a third arterial vessel, with the same high-resistance triphasic flow on pulsed Doppler, was suggestive of the superior thyroid artery.

Figure 2.

Representative TC images of CCA agenesis: 1a/b: Transverse and longitudinal images of CCA agenesis; 1c/d: 3D reconstruction of CT images of CCA agenesis, revealing the origin of right ICA and right ECA directly from the IA and their parallel course.

Figure 3.

Representative DUS images of ICA duplication: 3 a/b/c: two vessels originating from the right CCA, both with monophasic low-resistance flow, suggesting the presence of two ICA; 3d: a third vessel with a triphasic high-resistance flow was suggestive of the ECA; 3e: transverse projection were we saw three vessels (two ICA and one ECA), one close to the other.

Figure 4.

Prisma Flow Diagram of our systematic review. The total number of articles included in the review and the total number of excluded articles are described.