Background Type II spinal muscular atrophy (SMA) often leads to scoliosis in up to 90% of cases. While pharmacological treatments have shown improvements in motor function, their impact on scoliosis progression remains unclear. This study aims to evaluate potential differences in scoliosis progression between treated and untreated SMA II patients.
Methods Treatment effect on Cobb’s angle annual changes and on reaching a 50° Cobb angle was analysed in treated and untreated type II SMA patients with a minimum 1.5-year follow-up. A sliding cut-off approach identified the optimal treatment subpopulation based on age, Cobb angle and Hammersmith Functional Motor Scale Expanded at the initial visit. Mann-Whitney U-test assessed statistical significance.
Results There were no significant differences in baseline characteristics between the untreated (n=46) and treated (n=39) populations. The mean Cobb angle variation did not significantly differ between the two groups (p=0.4). Optimal cut-off values for a better outcome were found to be having a Cobb angle <26° or an age <4.5 years. When using optimal cut-off, the treated group showed a lower mean Cobb variation compared with the untreated group (5.61 (SD 4.72) degrees/year vs 10.05 (SD 6.38) degrees/year; p=0.01). Cox-regression analysis indicated a protective treatment effect in reaching a 50° Cobb angle, significant in patients <4.5 years old (p=0.016).
Conclusion This study highlights that pharmacological treatment, if initiated early, may slow down the progression of scoliosis in type II SMA patients. Larger studies are warranted to further investigate the effectiveness of individual pharmacological treatment on scoliosis progression in this patient population.
- SPINAL MUSCULAR ATROPHY
- PAEDIATRIC NEUROLOGY
Data availability statement
All data relevant to the study are included in the article or uploaded as online supplemental information.
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GC and JL are joint first authors.
Contributors GC, JL, MCP, AD’A, CB, CG, NB, MP, LA, MR, AC, GC, CC, RdS, SC, NF and MC were involved in the conception and design of the study, acquisition and analysis of data, and drafting a significant portion of the manuscript or figures. GC, JL, CG, NB, MBD, LL, FM and AL contributed to the acquisition and analysis of data and provided critical input during manuscript preparation. GC, JL and EM provided critical input during the conception and design of the study, data analysis, and manuscript preparation.EM supervised the entire study, including the conception and design, data analysis, and manuscript preparation, and made substantial contributions to all aspects of the research. EM takes full responsibility for the work and/or the conduct of the study, had access to the data, and controlled the decision to publish. All authors reviewed and approved the final manuscript.
Funding The work was partially funded from Biogen and Roche that are supporting the Italian registry and/or studies related to the use of its data.
Disclaimer Funders had no role in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; and in the decision to submit the paper for publication.
Competing interests GC, MCP, AD'A, MP, RdS, MC, EB, MP and EM have been a consultant for BIOGEN S.R.L. which owns patent rights to nusinersen of which data from patients in treatment were used in this study. GC, MCP, AD'A, MP, RdS, MC, EB, MP and EM have been a consultant for ROCHE which owns patent rights to risdiplam of which data from patients in treatment were used in this study.
Provenance and peer review Not commissioned; externally peer reviewed.
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