Steroids in Duchenne muscular dystrophy.

Steroids in Duchenne muscular dystrophy In his commentary [1] on our recent publication on glucocorticoids in Duchenne muscular dystrophy (DMD) [2], Professor Dubowitz raises the interesting possibility that the prolonged ambulation in Duchenne boys on continuous therapy in contrast to the intermittent schedule may be related to the marked stunting of growth secondary to the higher dose of corticosteroid in the former therapy. That height could have an effect on the clinical course of Duchenne muscular dystrophy has been suggested and explored in the past. One of the first observations was from Zatz et al. who reported one patient with congenital growth hormone deficiency in whom the disease course was clearly milder than in his siblings and cousins also affected by DMD but not by the growth hormone deficiency [3]. The same group subsequently published a study showing a significant negative correlation between height vs. motor ability, and weight vs. clinical course, suggesting that heavier patients had poorer performance, and that smaller boys had a slower progression of the disorder [4]. It is however important to highlight that height and weight were reported as actual values and were not converted to standard deviations; additionally their analysis did not take into account the age difference of the 93 patients studied (2–23 years); finally functional scores were not correlated to the BMI. Another issue, which should be taken into consideration, is that growth in these children occurs alongside muscle destruction, as a continuous phenomenon, and even with the most sophisticated statistical analysis, it may be challenging to interpret when a change occurs over time in relation to each other. In a longitudinal study on the 6-min walk distance (6MWD) test, comparing 18 boys with either Duchenne or Becker muscular dystrophy on steroids and 22 healthy controls, McDonald et al. reported that the major determinant of change in 6MWD was stride length; and changes in stride length in boys with muscular dystrophy were primarily dependent upon age-related disease progression, and not height. In this study, heights increased equally in both muscular dystrophy boys and healthy controls; but while stride length increased in healthy controls, it decreased in boys with dystrophy [5]. However, these boys were followed for a limited time only, which could explain why growth showed a similar pattern to healthy controls. Nevertheless, what this study shows is that growth occurs at the same time as progressive muscle weakness. An additional factor, …