Agenesis of Internal Carotid Artery
- Background:
- Internal carotid artery agenesis, hypoplasia, and aplasia are rare congenital anomialies occuring in only 0.01% of the general population.
- Agenesis of internal carotid artery increases the risk of developing aneurysms due to increased flow through the collateral arteries.
- Major collateral circulation may be recruited from the circle of Willis, embryonic vessels, or transcranial collaterals from the external carotid artery (ECA).
- Clinical Presentation:
- Patients may be asymptomatic or present with decreased visual acuity, unilateral weakness and numbness, slurred speech, headache, and drowsiness.
- Agenesis of internal carotid artery may occur as a component of PHACE syndrome.
- Key Diagnostic Features:
- Lack of ICA enhancement associated with absence of the petrous carotid canal within the skull base
- Abnormal ECA or collateral arteries are demonstrated on common carotid artery angiography.
- Differential Diagnosis:
- Internal carotid artery thrombosis
- ICA stenosis
- Moyamoya disease
- ICA vasospasm
