A Case of Positional Vertebral Artery Occlusion due to Physiological Cervical Extension with Occipital Condylar Spur

Positional vertebral artery occlusion(PVAO)is a mechanical occlusion of the extracranial vertebral artery(VA)due to physiological movement of the head and neck. However, only a few cases of mechanical VA compression due to routine flexion-extension of the neck have been reported. We present a unique case of PVAO due to neck extension with an occipital condylar spur. A 78-year-old man was admitted to our hospital for sudden onset of right hemiparesis and dysarthria. Magnetic resonance imaging(MRI)revealed bilateral occipital and cerebellar infarctions and vessel occlusion extending from the VA to the basilar artery. Mechanic thrombectomy resulted in partial recanalization. Computed tomography angiography(CTA)performed the next day showed spontaneously recanalized left VA with some wall irregularity. CTA in the neck-extended position revealed a severely compressed left VA in its V3 segment, which was attributed to the left occipital condylar spur with degenerative changes of the condyle-C1 facet. Cervical MRI also showed a pseudotumor from the lower clivus to the odontoid process that indicated mechanical stress on the occipitocervical ligaments. An occiput to C2 fusion was performed to stabilize and avoid dynamic vascular compression. Postoperative CTA revealed no evidence of restricted flow with flexion or extension movements of the neck. It should be noted that physiological head and neck movements accompanied by condylar degenerative changes could be a cause of vertebrobasilar insufficiency.