Scoliosis development in 5q-spinal muscular atrophy under disease modifying therapies

Purpose: 5q-spinal muscular atrophy (SMA) is a treatable neuromuscular disorder associated with scoliosis in up to 90% of patients. New SMA therapies could mark a paradigm shift in scoliosis management, but their effects on scoliosis development remain unclear. This study aims to observe scoliosis progression in the current treatment landscape to inform management strategies.

Methods: We conducted a cross-sectional retrospective analysis of 94 SMA patients treated at our center. Scoliosis development was evaluated in 75 patients using spine radiographs and electronic health records. Statistical analysis was performed using Python and GraphPad Prism. One-way ANOVA and Pearson correlation were used for group comparisons and correlation analysis, respectively.

Results: Scoliosis parameters in 5q-SMA patients who had received either nusinersen, onasemnogene abeparvovec, risdiplam, or their combinations showed mean ages at scoliosis detection were 23.94, 55.52, and 168.11 months for SMA types 1, 2, and 3, respectively. Cobb angles at detection showed no significant intergroup differences. The mean ages at scoliosis surgery were 60, 88.43, and 124.8 months. Pelvic obliquity (PO) was highest in type 1 and lowest in type 3. A strong correlation (r = 0.9) was found between PO measurement techniques. HFMSE scores correlated moderately with scoliosis severity (r = -0.38), while CHOP-INTEND showed no correlation.

Conclusion: The observations made in this study suggest that the effects of SMA therapies do not prevent scoliosis development. The improved prognosis may lead to a growing cohort of SMA type 1 and 2 patients with early onset scoliosis who require early growth-friendly surgical interventions.