A Systematic Review and Meta-Analysis of Surgical Outcomes for Cervical Myelopathy Associated With Athetoid Cerebral Palsy

1. What is the main research question? In patients with cervical myelopathy associated with athetoid cerebral palsy (ACP), does surgical approach influence the pooled reoperation rate? Specifically: • Is the reoperation rate higher in anterior-only fusion compared with posterior-involved procedures (posterior fusion alone + combined anterior–posterior fusion)? ________________________________________ 2. What are the key dependent variables? Primary outcome: • Reoperation rate (proportion of patients requiring reoperation during reported follow-up) Secondary outcomes: • Preoperative and postoperative Japanese Orthopaedic Association (JOA) score • JOA recovery rate • Demographic characteristics (sex proportion, age, follow-up duration) ________________________________________ 3. What are the key independent variables? Primary grouping variable: • Surgical approach (categorized as): o Anterior fusion only o Posterior-involved procedures (posterior only + combined anterior–posterior) Exploratory categories (not primary comparison): • Decompression only • Anterior fusion only • Posterior fusion only • Combined anterior–posterior fusion ________________________________________ 4. How will studies be selected? Inclusion criteria: • Clinical studies reporting surgical treatment for cervical myelopathy in patients with athetoid or dyskinetic cerebral palsy • Case series, retrospective cohort studies, or population-based retrospective cohort studies • Studies reporting extractable data for at least one of the following: o JOA score o Reoperation events o Surgical approach distribution Exclusion criteria: • Non-surgical studies • Studies without separable ACP data • Studies reporting only modified JOA (mJOA) for primary JOA pooling (retained for qualitative analysis only) ________________________________________ 5. What statistical models will be used? All quantitative syntheses will use random-effects meta-analysis. Proportion outcomes (e.g., reoperation rate, male proportion) • Logit transformation of event rates • Continuity correction (0.5) applied to zero-event studies • Random-effects pooling • Heterogeneity quantified using I² Continuous outcomes (JOA score) • Random-effects meta-analysis of means using inverse-variance weighting when mean ± SD are available • Studies lacking SD will be included only in descriptive N-weighted pooled means ________________________________________ 6. What is the primary hypothesis test? A single prespecified comparison: • Anterior-only fusion vs Posterior-involved procedures Subgroup difference will be evaluated using: • Random-effects subgroup comparison • Q_between statistic Significance threshold: • Two-sided p < 0.05 Because this is a single prespecified hypothesis, no multiple comparison correction will be applied. ________________________________________ 7. Will sensitivity analyses be performed? Yes. Because one national database study contributes a large proportion of patients, two analyses will be conducted: 1. Primary analysis including all studies 2. Sensitivity analysis excluding the national database study The subgroup difference test will be performed in both scenarios. ________________________________________ 8. How will missing data be handled? • Studies lacking SD will not be included in inverse-variance pooling. • Studies reporting follow-up only as a minimum duration (e.g., ≥5 years) will be treated descriptively. • No imputation of missing continuous data will be performed. ________________________________________ 9. What statistical software will be used? All analyses will be performed in R (R Foundation for Statistical Computing, Vienna, Austria). Meta-analyses will be conducted using R packages such as meta and metafor. All analysis scripts will be archived for reproducibility. ________________________________________ 10. What would constitute evidence against the hypothesis? If the random-effects subgroup comparison (Q_between) demonstrates: • p ≥ 0.05 in both the primary and sensitivity analyses, then the hypothesis that anterior-only fusion is associated with a higher reoperation rate would not be supported.