Hand weakness in Duchenne muscular dystrophy and its relation to physical disability.

The purpose of this study was to determine the age of hand involvement in Duchenne muscular dystrophy (DMD), since various types of hand dynamometry have been applied to evaluate patients in clinical trials. We studied 40 patients with DMD from our university hospital clinic and 80 healthy, age-matched controls. Hand strength was evaluated by handgrip and pinch dynamometries, and by manual testing. Physical disability was measured with a functional scale. Hand weakness was present since early stages in patients with DMD. However, hand strength tended to increase with age in the first decade, although never reaching the control values. Decrease of strength occurred later. Handgrip and pinch dynamometry values were significantly correlated with global hand strength, which were inversely correlated with functional capacity only in the group older than 10 years. Hand dynamometry should be applied with caution as an outcome measure in therapeutical trials in young patients with DMD.