Elsevier

World Neurosurgery

Volume 95, November 2016, Pages 620.e9-620.e15
World Neurosurgery

Case Report
Bilateral Internal Carotid Artery Segmental Agenesis: Embryology, Common Collateral Pathways, Clinical Presentation, and Clinical Importance of a Rare Condition

https://doi.org/10.1016/j.wneu.2016.08.012Get rights and content

Background

Bilateral segmental agenesis of the internal carotid artery is a rare congenital anomaly. We present a case of bilateral internal carotid artery segmental agenesis in an asymptomatic 18-year-old man. Embryology, common collateral pathways, clinical presentation, and clinical importance of this condition are discussed. According to our review of the literature, this report is the first to describe bilateral internal carotid artery segmental agenesis in a patient studied with magnetic resonance imaging, computed tomography, Doppler ultrasonography, and digital subtraction angiography.

Case Description

An 18-year-old man presented to our hospital complaining of occasional mild headaches. Neurologic examination was unremarkable. Imaging findings consisted of bilateral segmental agenesis of the internal carotid arteries.

Conclusion

Bilateral segmental agenesis of internal carotid artery may be completely asymptomatic and harmless, but associated conditions, such as cerebral aneurysms or abnormal collateral circulation, should alert clinicians to the possibilities of subarachnoid hemorrhage or cerebral ischemia.

Section snippets

Background

Congenital absence of the internal carotid artery (ICA) is a rare congenital anomaly in common clinical practice. The terminology “absence” encompasses a spectrum of abnormalities other than agenesis. Agenesis occurs in <0.01% of the population.1, 2 Only <10% of those cases have bilateral occurrence.3 Hypoplasia is prevalent at 0.079%.

Agenesis and aplasia mean absence of the vessel. Hypoplasia is characterized by ICA narrowing along its entire course as a reflection of incomplete development.

Case Description

An 18-year-old Caucasian man presented to our hospital with occasional mild headaches. Neurologic examination revealed normal findings. Despite medical treatment, headache persisted. As a result, more advanced investigations were performed.

MRI showed no brain abnormalities, while magnetic resonance angiography, performed with both 3-dimensional (3D) time-of-flight and postgadolinium 3D-fast spoiled gradient echo sequences, showed bilateral agenesis of the cervical segments of the ICAs.

Discussion

The spectrum of ICA malformation is widely variable and can range from complete absence of the artery (agenesis or aplasia) to absence of a single section or reduction in its dimension (hypoplasia).

The ICA derives from the third aortic arch, and its formation is essential for further development of the carotid canal. Therefore the absence of the carotid canal signifies that the alteration has occurred between the third and fifth weeks of embryonic development, during which the ICA is defined,

Conclusion

Bilateral internal carotid segmental agenesis may be completely asymptomatic and harmless, but associated conditions, such as cerebral aneurysms or abnormal collateral circulation, should alert clinicians to the possibilities of subarachnoid hemorrhage or cerebral ischemia. Furthermore, human carotid rete mirabile, commonly associated with carotid hypoplasia/agenesis, even if it has no inherent pathologic significance, must be recognized because it has important implications in the surveillance

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    Conflict of interest statement: None of the authors has a conflict of interest to declare, and none of them received financial support.

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