Sectioning of C2 nerve roots during C1–2 fusion: report of aberrant vertebral artery during C2 nerve root sectioning. Illustrative case

BACKGROUND: Sectioning the C2 nerve root is increasingly utilized during posterior C1–2 fusion, as the nerve overlies the entry point for C1 lateral mass screws and the C1–2 joint. Nerve sectioning improves visualization for screw placement and enables joint decortication for arthrodesis. While rare, vascular injury is a devastating complication of atlantoaxial fusion. Anomalous vascular anatomy at C1–2 greatly increases risk of iatrogenic injury. OBSERVATIONS: A 78-year-old female with rheumatoid arthritis and prior C2–7 fusion presented with myelopathy from a compressive pannus at C1–2. She underwent C1 laminectomy and C1–2 posterior instrumented fusion. Intraoperatively, arterial bleeding occurred as the right C2 nerve root was sectioned. Vertebral artery injury was suspected, and tamponade was performed while vascular control was established. The artery passed aberrantly beneath the nerve root in the C1–2 foramen. It was repaired microsurgically, and patency was confirmed using indocyanine green. The remainder of the fusion was aborted. The patient wore a cervical collar and was treated with aspirin for 6 weeks before undergoing instrumented fusion. The patient suffered no deficits. LESSONS: Although rare, anomalous vertebral artery anatomy increases risk of injury at time of C2 nerve root sectioning. Preoperative assessment of the vasculature is vital.