Unusual origin of the left vertebral artery

Introduction The vertebral artery (VA) is important to posterior cerebral circulation. It arises from the superior surface of the first part of the subclavian artery medial to the scalenus anterior muscle. The vessel takes a vertical posterior course to enter into the transverse process of the sixth cervical vertebra. It continues through the transverse foramina of the cervical vertebrae and after passing through the transverse foramen of the atlas, turns posteromedially on its posterior arch, pierces the atlantooccipital membrane and the dura mater, respectively and then enters the foramen magnum [1,2]. The segment of the VA from its origin at the subclavian artery to its entry into the respective transverse foramina is called the pretransverse or prevertebral segment [2]. Several researchers have reported anomalous origins of the VA such as from the aortic arch, between the left common carotid artery (LCCA) and left subclavian artery (LSA) or after LSA, from the thyrocervical trunk, from the brachiocephalic trunk (BT), from the common carotid artery, from the external carotid artery, from a common carotid trunk formed by LSA and left vertebral artery (LVA) [3–7]. Knowing the variation of the origin of VA and its prevertebral course is of great importance for head and neck surgery [8] and angiography [2] and vascular angiography.