Fenestration of the vertebral artery at the lower cervical segment—imaging findings and literature review

Complex aortic arch anomaly: Right aortic arch with aberrant left subclavian artery, fenestrated proximal right and duplicated proximal left vertebral arteries-CT angiography findings and review of the literature

Congenital aortic arch and vertebral artery anomalies are a relatively rare finding discovered on imaging either incidentally or for evaluation of entities like dysphagia or subclavian steal. Right aortic arch is an uncommon anatomical anomaly that occurs in less than 0.1% of the population, and in half of these cases the left subclavian artery is also aberrant.(1) Unilateral vertebral artery (VA) duplication is rare with an observed prevalence of 0.72% in cadavers.(2) Fenestration of the VA is more common than duplication, with a prevalence of approximately 0.23%-1.95%.(3,4) We describe the case of a 25-year-old female who was found to have a right aortic arch with aberrant left subclavian artery, duplicated left vertebral artery and a fenestrated right vertebral artery on CT angiography performed for evaluation of dysphagia. This combination of findings has not been reported before, to the best of our knowledge. We review the embryologic mechanism for the development of the normal aortic arch, right aortic arch, vertebral artery duplication and vertebral artery fenestration. The incidence of these entities, resultant symptoms and clinical implications are also reviewed. The increased associated incidence of aneurysm formation, dissection, arteriovenous malformations and thromboembolic events with fenestration is also discussed.

Fenestration and duplication of the vertebral artery: the anatomical and clinical points of view

The vertebral artery (VA) acts as a foundation for the posterior circulation of the head and neck. It presents a number of anomalies that can be easily visualized thanks to modern imaging techniques, such as MR and CT angiography or color Doppler ulrasonography. Determining the appropriate terminology for those anomalies can be sometimes more challenging than their recognition. One particular challenge concerns the differentiation between VA fenestration and duplication. Because of the different clinical prognoses associated with those anomalies, confusion should be avoided. Knowledge of the morphological anomalies associated with the VA is important for both radiologists and head and neck surgeons, because any injury to the VA can result in a threat to the vascular supply of the brain stem, the cerebral or cerebellar hemispheres, the thalamus, cervical nerve roots and particularly the lateral medulla (Wallenberg's syndrome). This article analyses world literature concerning the issue of VA fenestration and duplication to facilitate a differential diagnosis.