Children with spinal muscular atrophy treated with disease-modifying therapies, do they attain neutral vertical head and trunk control?

Aim: To investigate whether children with various spinal muscular atrophy (SMA) subtypes treated with disease-modifying therapies (DMT) obtain neutral vertical (NV) head and trunk control, and how this relates to motor function. Method: In this observational cross-sectional study, a convenience sample of 21 children diagnosed with SMA (6y1m (4y), 10 female) was tested with Segmental Assessment of Trunk Control (SATCo) and functional assessments. A linear mixed-effects model (LME) was used for statistical analysis. Results: SATCo scores were measurably different between condition (types of SMA), F=4.96, p<.05, and control type (static, active, and reactive control), F=6.40, p<.05. The interaction condition*control type was also significant, F=3.14, p<.05. No child with SMA1 demonstrated NV head control and there was no relationship between SATCo scores and motor function. Four children with SMA2 and SMA3 demonstrated NV head static control, and one demonstrated NV mid-thoracic static control. Interpretation: The results indicate that children with SMA treated with DMTs acquire very little or no unsupported NV head/trunk control. SATCo was shown to be sensitive to differences in trunk control in different types of SMA revealing potential as an outcome measure for therapeutic interventions or treatment effectiveness. Further studies are needed to clarify this potential.