From the case:
Fenestration of the vertebral artery
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Incidental finding of fenestration of the distal (V4) left vertebral artery. No aneurysm. The right vertebral artery is poorly seen. It is unclear if it is hypoplastic or has poor flow due to a proximal stenosis.
Case Discussion
Fenestration is the division of the lumen of the vessel into two separate and parallel channels which rejoin distally. It usually does not have any clinical significance but an aneurysm may arise typically from the proximal part of fenestration.