Congenital absence of the internal carotid artery

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, it 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.

Anatomy: Brain
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Article information

rID: 12646
Section: Anatomy
Synonyms or Alternate Spellings:
  • hypoplastic ICA
  • absent ICA
  • Congenital hypoplasia of the internal carotid artery
  • Congenital aplasia of the internal carotid artery
  • Congenital agenesis of the internal carotid artery

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