Unilateral C1-C2 Posterior Fusion in a Patient With Right Vertebral Artery Anomaly With Intracanal Trajectory

A 59-year-old woman presented with progressively worsening neck pain and radicular symptoms. Cervical radiographs revealed C1-C2 dynamic instability. Magnetic resonance imaging and computed tomographic angiogram revealed an anomalous right vertebral artery with intracanal trajectory at C1. A unilateral left C1-C2 fusion with a C1 lateral mass screw and C2 transarticular screw placement was performed due to the anomalous artery. At 14-month follow-up, the patient's cervical symptoms had resolved.