Congenital absence of the internal carotid artery

Last revised by Mohamed Saber on 23 Jul 2022

Congenital absence of the internal carotid artery (ICA) is a rare anomaly that occurs in less than 0.01% of the population. It encompasses agenesis, aplasia, and hypoplasia 1.

The most common type of collateral flow is through the circle of Willis, through the anterior communicating artery (ACom) and posterior communicating artery (PCom). Less commonly, collateral flow is provided via persistent embryonic vessels or from transcranial collaterals originating from the external carotid artery (ECA) system.

Although many of these cases remain asymptomatic and go undetected, congenital absence of the ICA is associated with cerebral aneurysms. Also, these anomalies have important implications during carotid endarterectomy and transsphenoidal hypophyseal surgery, and in the setting of thromboembolic disease.

Related pathology

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Cases and figures

  • Case 1
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  • Case 2
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  • Case 3
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  • Case 4
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  • Case 5: with aneurysms
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  • Case 6: congenital hypoplasia
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