Posterior C2–C5 Instrumented Fixation for Cervical Spondylolisthesis with Medialized Vertebral Arteries: A Case Report

Abstract Vertebral artery (VA) anomalies increase the risk of catastrophic complications during cervical spine surgery, particularly in anterior cervical discectomy and fusion (ACDF). Medial migration of the VA into the operative corridor substantially elevates the risk of VA injury (VAI). Early recognition on preoperative imaging is essential. A 50-year-old gentleman presented with 6 months of progressive numbness and loss of fine motor dexterity in both hands. Preoperative computed tomography (CT) showed C3/4 grade II anterolisthesis with moderate cord compression, and medialized foramen transversum bilaterally at C4. CT angiogram (CTA) showed tortuous bilateral medial looping VAs. Given the elevated risk of VAI, single-level 360-degree fusion (ACDF with single-level posterior instrumented fusion) was abandoned in favor of posterior-only multilevel fixation. C2 pedicle screws and C3–C5 lateral mass screws were inserted under three-dimensional (3D) navigation, and satisfactory reduction and stability was achieved. The patient recovered uneventfully and was discharged on day 23 after rehabilitation with just left C6 numbness and improving dexterity. At 6- and 12-month follow-up, he regained full dexterity and power in both upper limbs with only some neck stiffness and left palm numbness. Modified Japanese Orthopaedic Association score increased from 14 preoperatively, to 16 at 6 months and 17 at 12 months. X-rays done on postoperative day 1, 6 months, and 12 months showed satisfactory implant positioning. Four management suggestions have been proposed. Surgeons must actively scrutinize initial imaging for foraminal transversaria anomalies and maintain a low threshold for CTA to properly delineate any tortuous VAs. This was crucial for our preoperative planning. Second, posterior-only multilevel fixation provides good biomechanical stability and could potentially be an alternative to current anterior and 360-degree approaches. Screw selection and construct length must reflect both anatomical constraints and nonstandard mechanical demands. Lastly, 3D intraoperative navigation is a highly useful adjunct, especially in cases of vascular anomalies where the margin for safe instrumentation is often narrow. Current literature is restricted to cervical myelopathy and low-grade degenerative spondylolisthesis. There are no published series addressing grade two cervical spondylolisthesis, particularly with VA anomalies. Hence, this case constitutes a unique contribution to current evidence.