Bow Hunter's Syndrome

A 58-year-old man with a history of obesity, hyperlipidemia, and anxiety was referred to the cerebrovascular clinic with intermittent dizziness when turning his head to the right. These symptoms started at least a year before presentation but were becoming more frequent and severe. He further described the dizziness as feeling like a head rush without a room-spinning sensation. It occurred while standing, sitting, or lying but always in the setting of turning his head to the right. He also described mild bilateral hearing loss and tinnitus over the last 10 years. The patient denied diplopia, nausea, vomiting, or headache. He had no history of falls or gait instability. He was previously evaluated in otolaryngology clinic and was told his symptoms were inconsistent with peripheral vertigo. The patient s initial neurological examination was significant for normal mental status, normal cranial nerves except for mild decreased hearing bilaterally, normal strength without drift, intact sensation to light touch, and normal reflexes. There was no frank ataxia, but there was instability with tandem gait. Both Romberg and Dix-Hallpike tests were negative. The symptoms could be intermittently induced with right head turn. Head and neck computed tomography angiography revealed a C5-C6 osteophyte in proximity to the right vertebral artery (Figure 1). Cervical vertebral artery dynamic ultrasonography revealed increased peak systolic flow velocity from 50 to 159 cm/s with right head turn (Figure 2A and 2B). There was no effect with left head turn (Figure 2C). Intracranial vertebral artery dynamic transcranial Doppler demonstrated reduced peak systolic flow velocity from 24 to 15 cm/s with right head turn (Figure 2D). Digital subtraction angiography revealed the right vertebral artery was unremarkable in the standard position, but turning the head to the right elicited a focal region of stenosis (Figure 3A and 3B). The left vertebral artery was congenitally hypoplastic (Figure 3C). Furthermore, there was a chronic-appearing mid-basilar occlusion, and the bilateral posterior cerebral arteries, bilateral superior cerebellar arteries, and basilar artery tip were supplied by the anterior circulation through the right posterior communicating artery (Figure 3D and 3E). Given the risks associated with surgical intervention for the osteophyte near the right vertebral artery, particularly in the setting of a hypoplastic left vertebral artery, the patient and care team pursued conservative treatment with behavioral modification to minimize right head turning. He was also treated with aspirin 325 mg and atorvastatin 80 mg. The vertebral arteries will be monitored yearly with ultrasonography. © 2021 American Heart Association, Inc