Bow hunter’s syndrome: temporary obstruction of blood flow in the affected vertebral artery during posterior occipitocervical fusion. Illustrative case

BACKGROUND: Bow hunter’s syndrome (BHS) is a rare condition characterized by mechanical impingement of a vertebral artery (VA) during neck rotation followed by vertebrobasilar insufficiency. Posterior fusion is a typical surgical method for BHS. OBSERVATIONS: The case of a 70-year-old Japanese man who presented with presyncope that occurred during right cervical rotation is reported. Given the possibility of vertebrobasilar insufficiency, digital subtraction angiography and computed tomography angiography were performed and showed a hypoplastic right VA and severe stenosis of the left VA over the occiput (O)–C2 level. The blood flow of the left VA was interrupted by right cervical rotation, with resumption of blood flow on left cervical rotation. BHS was diagnosed, and posterior fusion at the O–C2 level was performed. Immediately after implant fixation, selective arteriography confirmed disruption of blood flow in the left VA. The rods were removed immediately; resumption of blood flow was confirmed; and the rods were refixed, anatomically bent with slight left cervical rotation. Then, sustained blood flow in the left VA was confirmed. LESSONS: Posterior fixation for BHS can induce VA occlusion due to minor changes in cervical spine alignment. Intraoperative selective arteriography is a necessary tool to identify occlusion of the affected VA.