A Rare Vascular Variation: Left Vertebral Artery Arising as the Fourth Branch of the Aortic Arch

Abstract Vascular variants can significantly influence surgical planning and diagnostic accuracy. One rare anomaly is that of the left vertebral artery arising directly as the fourth branch of the aortic arch, lateral to the left subclavian artery. We describe a 52-year-old male in whom this variation was found incidentally during evaluation for an acute right medullary infarct and a focal aneurysm of the right vertebral artery. The aberrant origin was confirmed by computed tomography angiography. Such variants are important in relation to anterior cervical spine surgery, vertebral artery dissection, carotid stenting, and other endovascular procedures. Awareness of these anomalies is crucial for the avoidance of intraoperative injury and optimization of neurovascular management.