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40-Year-Old Male with Dizziness
This case features a 40-year-old male presenting with dizziness, ultimately diagnosed with congenital absence of the intracranial internal carotid artery (ICA).
Imaging overview:
Axial NECT and axial SWI sequences demonstrate absence of the right intracranial ICA with absence of the corresponding carotid canal. Robust collateral flow is established via posterior communicating artery collaterals, identified on SWI as prominent flow-related signal in the posterior circulation.
Clinical insight:
Congenital absence of the intracranial ICA is a rare vascular anomaly occurring in less than 0.01% of the population, with a left-sided predominance of 3:1. The key imaging feature distinguishing it from chronic ICA occlusion is the absence of the carotid canal on CT, reflecting failure of vessel development rather than acquired occlusion. Collateral supply typically develops through the posterior and anterior communicating arteries. Patients carry an increased risk of intracranial aneurysms, making thorough vascular imaging essential at the time of diagnosis and during follow-up.
Case courtesy of Abel T. Abebe, MD and Huda Al Jadiry, MD,
The University of Texas Medical Branch at Galveston.