Deflazacort Attenuates the Progression of Scoliosis in Duchenne Muscular Dystrophy

The Hospital for Sick Children and the Bloorview MacMillian Centre
Toronto, Ontario, Canada.

PURPOSE:
Several studies found that steroid treatment preserves muscle function in Duchenne Muscular Dystrophy (DMD). Deflazacort is a derivative of prednisolone that has fewer side effects than prednisone. This study was performed to determine if deflazacort attenuates the progression of scoliosis in boys with DMD.

METHODS:
Patients with DMD who participated in a comparative study to determine the effect of deflazacort on muscle strength and pulmonary function were reviewed. The boys were between the ages of 7 and 15 at the start of the study. There were 30 boys treated with deflazacort and 24 who were not (average age was 10 in both groups at the start of the study). The boys in each group were followed for five years. Patients were reviewed twice a year using physical examination and radiographs to check for scoliosis. Data from the initial study of this cohort found that boys using deflazacort walked for almost three years longer than boys who did not use deflazacort, and deflazacort treatment resulted in a higher functional vital capacity (e.g. 80% -vs- 45% predicted value at age 15). Children who developed a curve of at least 20 degrees or who had a functional vital capacity declining towards 40% were considered for surgical treatment.

RESULTS:
Of the 24 boys not treated with deflazacort, 16 (66%) developed a curve of at least 20 degrees during the time of follow-up. In contrast, only five of the 30 patients (17%) treated with deflazacort developed a curve of at least 20 degrees. 15 of the 24 boys not treated with deflazacort underwent spine surgery at a mean age 13 years, while 5 of the 30 boys treated with deflazacort underwent surgery at a mean age of 15.

CONCLUSION:
Besides its effects on muscle strength, Deflazacort treatment slows the progression of scoliosis in boys with DMD. It is unclear if treatment will halt the progression of scoliosis, or if it will merely delay its onset until later in life. Further evaluation of these boys will be necessary to determine the long-term outcome.