Abstract
Background: Muscles of boys with Duchenne muscular dystrophy (DMD) are progressively replaced by fatty fibrous tissues, and weakness leads to loss of ambulation (LoA). Step activity (SA) monitoring is a quantitative measure of real-world ambulatory function. The relationship between quality of muscle health and SA is unknown in DMD. Objective: To determine SA in steroid treated boys with DMD across various age groups, and to evaluate the association of SA with quality of muscle health and ambulatory function. Methods: Quality of muscle health was measured by magnetic resonance (MR) imaging transverse magnetization relaxation time constant (MRI-T2) and MR spectroscopy fat fraction (MRS-FF). SA was assessed via accelerometry, and functional abilities were assessed through clinical walking tests. Correlations between SA, MR, and functional measures were determined. A threshold value of SA was determined to predict the future LoA. Results: The greatest reduction in SA was observed in the 9- < 11years age group. SA correlated with all functional and MR measures.10m walk/run test had the highest correlation with SA. An increase in muscle MRI-T2 and MRS-FF was associated with a decline in SA. Two years prior to LoA, SA in boys with DMD was 32% lower than age matched boys with DMD who maintained ambulation for more than two-year period. SA monitoring can predict subsequent LoA in Duchenne, as a daily step count of 3200 at baseline was associated with LoA over the next two-years. Conclusion: SA monitoring is a feasible and accessible tool to measure functional capacity in the real-world environment.
Original language | English (US) |
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Pages (from-to) | 423-436 |
Number of pages | 14 |
Journal | Journal of Neuromuscular Diseases |
Volume | 9 |
Issue number | 3 |
DOIs | |
State | Published - 2022 |
Keywords
- 10m walk/run test
- MRI
- Step activity
- duchenne muscular dystrophy
- fat fraction
ASJC Scopus subject areas
- Neurology
- Clinical Neurology