The Motor Function Measure (MFM) is widely used to assess severity and progression of neuromuscular diseases. Validity was established in a group of patients aged 6-60 years with suspected or confirmed diagnosis of neuromuscular diseases, Duchenne Muscular Dystrophy being the most frequent diagnosis in the population tested.
Our aim was to check the validity of the MFM in a hospital department specialized in neuromuscular diseases in the follow-up of adult out-patients presenting a myopathy, such population being very different from the MFM validation group in terms of age and sub-groups of myopathy.
One hundred patients were randomly selected in the Reference Center for Neuromuscular Diseases of Nice (France) between 2005 and 2007. Were collected: the MFM score, manual muscular testing (MMT) of lower and upper limb, face and spine, Brooke and Vignos scores. MFM and its three dimensions D1 (standing position and transfers), D2 (axial and proximal limb motor function) and D3 (distal motor function) were compared to the other scores with the Spearman Correlation Coefficient and the Principal Component Analysis.
Patients were aged 18-78 years. The most frequent diagnoses were Steinert's Muscular Dystrophy (DM1) and Facio-ScapuloHumeral Dystrophy (FSHD) (30% and 29%). MFM was significantly correlated to all other scores except for Face MMT. However, Face MMT was correlated to D1 and D2 in DM1 patients and to D2 in FSHD patients.
Our results confirm the validity of the MFM in adult patients with muscular diseases. However, the MFM global score and its three dimensions D1, D2 and D3 are variously correlated with the facial and axial muscle testing. Therefore, we recommend using separately the three dimensions D1, D2, D3 (rather than the global score) and, if more accuracy is required, the facial and axial muscle testing.