A Case of Bow Hunter's Syndrome Caused by C3/4 Facet Joint Hypertrophy: Hemodynamic Complexity and Surgical Strategy.

Bow Hunter's syndrome results from rotational insufficiency of the vertebral artery. Though traditionally associated with C1-C2 level compression, subaxial cervical causes are increasingly recognized. We report a 68-year-old man with codominant vertebral arteries presenting with dizziness and transient visual disturbances during head rotation. Imaging showed severe focal stenosis caused by an osteophyte at the left C3-C4 facet joint. Dynamic angiography revealed that the left vertebral artery was nearly occluded during rotation; despite faint distal residual flow, contrast failed to reach the basilar artery. The patient underwent a left C3-C4 facetectomy and posterior C2-C5 fusion. Intraoperative angiography confirmed restoration of antegrade flow, and the patient's symptoms resolved postoperatively. Identifying the underlying hemodynamic mechanism and selecting an appropriate surgical route are important for the successful management of this condition.