P.120 - Segmental body composition in young children with SMA type 2: Correlation with motor function abilities

Abstract

The aim of the present study was to investigate the correlation between fat mass (FM) and fat-free mass (FFM), measured by total and segmental body dual energy x-ray absorptiometry (DEXA), and the Hammersmith Functional Motor Scale Expanded (HFMSE) and the Upper limb module (ULM). 40 children with SMA type 2 (mean age 4.07 ± 1.90 years) were included in the study. Total FFM and FM were not correlated with HFMSE scores. However, when we investigated the correlation of segmental FFM and FM with motor function scores, we found that lower limbs FFM was significantly correlated with HFMSE scores (r = 0.375; p = 0.017), while no correlations were found between upper limbs FFM and HFMSE (r = 0.050; p = 0.756) or ULM (r = 0,154; p = 0,392). When we divided the whole cohort into Low-Functioning (HFMSE < 12) and High-Functioning (HFMSE > 12) children, we found that the Low-Functioning group had lower upper and lower limbs FFM, and higher upper and lower limbs FM, compared to the High-Functioning group. To our knowledge this is the first study investigating the correlation between total and segmental body composition and motor function in young children with SMA 2. The present study demonstrated that segmental lean mass at the lower limbs was correlated with global motor function abilities, as assessed by the HFMSE, and that segmental lean and fat mass was significantly different when children were stratified by level of functional abilities. These data further highlight the validity of HFMSE as an outcome measure in SMA, and may be helpful in monitoring the effects of therapeutic strategies.