Congenital absence of the internal carotid artery

Case contributed by Khaloud Alghamdi


Right cerebral infarct six weeks ago. Transient worsening. Rule out new ischemic lesion.

Patient Data

Age: 75 years
Gender: Male

Encephalomalacia affecting the right corona radiata, extending to the body of the caudate nucleus and also the right putamen and posterior limb of right internal capsule.

Presence of moderate periventricular white matter leukoencephalomalacia.

No left carotid artery is visualized. The left carotid bony canal is absent.The left posterior communicating artery is prominent likely due to colateral flow to compensate for absent left ICA.

There is loss of normal flow void of the left internal carotid artery, in keeping with known congenital absence of the left internal carotid artery seen on ultrasound.  

Old infarction in the right corona radiata with volume loss and mildly prominent right lateral ventricle

Moderate to advanced chronic microvascular ischemic changes as demonstrated by signal abnormalities in the T2 and FLAIR weighted images.

On the left side there is no clear demonstration of the left internal carotid. The common carotid is visualized arising from the arch and continues in and unobstructed fashion as the external carotid artery. The doppler signals within the vessel are of high resistance way form throughout indicating no significant connection to the low resistance internal carotid system. This raises the possibility that the patient has a significant vascular anomaly as congenital absence if the internal carotid artery.

Both vertebral arteries are patent. Abnormally low bifurcation of the right common carotid.

Case Discussion

Given the patient's age, lack of major ischemic change, and doppler ultrasound findings the most probable diagnosis is congenital absence of the left internal carotid artery.

The case was contributed by Dr Raquel Del Carpio-O'donovan, Professor of Radiology, Neurology, Neurosurgery at McGill University.

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Case information

rID: 78897
Published: 17th Jun 2020
Last edited: 18th Jun 2020
Inclusion in quiz mode: Included
Institution: McGill University

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