Simultaneous Bilateral Vertebral Artery Occlusion in the Lower Cervical Spine Manifesting as Bow Hunter's Syndrome -Case Report-

Abstract

A 59-year-old male had suffered near-syncopal episodes for more than one year that occurred immediately on turning his head to the left. Cerebral magnetic resonance (MR) imaging did not detect any contributing lesions with well-developed posterior communicating arteries. Dynamic radiography of the cervical spine showed mild instability at C5-6 and concomitant intramedullary hyperintensity confirmed by T(2)-weighted MR imaging. Cervical computed tomography demonstrated an osseous protrusion in the right foramen transversarium at C5. Dynamic cerebral angiography revealed simultaneous vertebral artery (VA) occlusion at C6 on the right and C5 on the left associated with leftward head rotation. The VA showed an intact course at the C1 to C2 levels. The patient underwent anterior fusion followed by decompressive foraminotomy at C5-6 and C6-7 and meticulous resection of the markedly thickened fibroligamentous structure which was considered to contribute to the rotational VA occlusion. Postoperatively he no longer suffered near-syncope during head rotation. Bow hunter's syndrome is an infrequent type of vertebrobasilar insufficiency that may need surgical management for potential threat of ischemic stroke. Simultaneous VA occlusion at the lower cervical level can cause bow hunter's syndrome. Dynamic cerebral angiography is a useful modality for evaluating bow hunter's syndrome even if the patient cannot tolerate dynamic examination for the immediate symptom. Accurate anatomical knowledge of the uncovertebral foraminal region combined with intraoperative dynamic study is essential for safe surgery to the VA and favorable outcome.