Does Transection of the C2 Nerve Roots During C1 Lateral Mass Screw Placement for Atlantoaxial Fixation Result in a Superior Outcome?: A Systematic Review of the Literature and Meta-analysis.

STUDY DESIGN: Systematic review and meta-analysis.

OBJECTIVE: To evaluate the clinical and functional outcomes of transection of the C2 roots during C1 lateral mass screw placement for atlantoaxial fixation.

SUMMARY OF BACKGROUND DATA: Transection of the C2 nerve roots has been recommended during atlantoaxial fixation to facilitate C1 lateral mass screw placement and possibly reduce postoperative occipital neuralgia, although this practice remains controversial.

METHODS: We searched MEDLINE, EMBASE, Web of Science, and the Cochrane Library for studies evaluating the outcomes of C1-2 fixation involving sacrifice of the C2 roots. We calculated transformed proportions with 95% confidence intervals (CI) for the outcomes of occipital neuralgia, numbness, bony fusion, and procedural morbidity. For studies comparing C2 transection with nerve sparing surgery, we performed meta-analyses for the outcomes of occipital neuralgia, occipital numbness, blood loss, and operative time.

RESULTS: Eight observational studies (N = 393) met eligibility criteria. The rate of postoperative occipital neuralgia among included studies was 0% to 25%; occipital numbness, 6.7% to100%; bony fusion, 96.7% to 100%; and procedural morbidity, 0% to 14.3%. Among comparative studies, C2 transection was associated with a higher rate of occipital numbness [odds ratio (OR) 178.6 (95% CI 26.6 to 1198.4)], lower blood loss [mean difference (MD) -195.3 mL (95% CI -317.7 to -72.8 mL)] and shorter operative times [MD -57.5 mins (95% CI -76.9 to -38.2 mins)] than when the C2 roots were spared. We found no difference in rates of occipital neuralgia [OR 1.44 (95% CI 0.45 to 4.68)].

CONCLUSION: Transection of the C2 nerve roots appears to be a viable, safe option when undertaking placement of C1 lateral mass screws. The procedure is associated with reduced operative duration and blood loss, increased rate of occipital numbness, and no change in the rate of occipital neuralgia. However, given the relatively low quality of evidence, prospective, controlled studies to evaluate this strategy are recommended.

LEVEL OF EVIDENCE: N /A.