Background: Duchenne muscular dystrophy (DMD) inflicts a progressive degeneration of both pulmonary and motor function. While existing research predominantly addresses non-ambulatory DMD patients, a critical gap exists in understanding the nuanced changes in ambulatory individuals.
Objectives: This study endeavors to delineate the intricate patterns of alterations in pulmonary and motor function among ambulatory DMD patients receiving corticosteroid therapy for at least one year.
Methods: Employing a cross-sectional design, we recruited 48 ambulatory DMD patients aged 5.0-12.0. Respiratory function was meticulously assessed using spirometry, while limb muscle strength was measured through manual muscle testing (MMT). Additionally, motor function was comprehensively evaluated using the North Star Ambulatory Assessment (NSAA) score and four timed function tests.
Results: Peak Expiratory Flow (PEF%) exhibited a significant increase during the cohort (P1=0.016). Positive correlations were observed between Forced Vital Capacity (FVC%) and NSAA score (r=0.275, P=0.007), as well as between Forced Expiratory Volume in 1 second (FEV1%) and NSAA score (r=0.206, P=0.044). Conversely, FVC% showed negative correlations with the walk up 4 stairs (r=-0.237, P=0.025) and walk down 4 stairs (r=-0.283, P=0.008) tests. In subjects under 7 years old, FVC%, FEV1%, PEF%, and Maximal Mid-Expiratory Flow (MMEF%) demonstrated significant increases.
Conclusion: Our study unveils a nuanced interplay between pulmonary and motor function in ambulatory DMD patients under corticosteroid therapy. Despite a progressive decline in motor function, a notable improvement in pulmonary function was identified, particularly in individuals under 7 years old. This study underscores the mild linkage between pulmonary and motor functions and highlights age, NSAA scores, and limb muscle strength as crucial contributors to pulmonary function changes in ambulatory DMD patients. These findings offer valuable insights for tailored interventions in this patient cohort.