Steroid-Treated DMD Boys
Walk Longer, Have More Fractures

Boys with Duchenne muscular dystrophy (DMD) who were treated daily for at least a year with corticosteroid medications walked longer and were less likely to develop a spinal curvature (scoliosis), but they were more likely to experience fractures of their vertebrae and long leg bones.

Neurologists Jerry Mendell and John Kissel, co-directors of the MDA clinic at Ohio State University Medical Center in Columbus, with Wendy King, physical therapist associated with the clinic, and colleagues, published these results May 8 in Neurology, after reviewing the records of 143 patients seen at the MDA clinic between 2000 and 2003.

Seventy-five of the boys took prednisone at 0.75 milligrams per kilogram per day or deflazacort at 0.9 milligrams per kilogram per day, and 68 boys had either never taken corticosteroids or received only brief, low-dose treatment.

The treated boys walked independently for an average of 3.3 years longer than did the untreated boys.

In addition, nearly three times as many untreated compared to treated young men developed a spinal curvature serious enough to be referred for surgery. The authors speculate that the lower frequency of scoliosis in the treated group may reflect stronger muscles supporting the spine and/or prolonged walking. They said they couldn’t determine whether corticosteroids truly prevent scoliosis or just delay its onset.

About a third of the treated boys experienced fractures of the vertebrae related to compression in the spine, whereas no untreated boy did. The authors note, however, that about 80 percent of these fractures were discovered incidentally during scoliosis screening and not because of pain reported by patients. The authors say the increased risk of compression fractures could be related to more walking and greater body weight.

Almost a third of the boys in the steroid group had a fracture of a long leg bone (femur), compared with only 7 percent of the untreated boys. However, fractures of the upper arm bone (humerus) occurred in only 9 percent of the steroid-treated boys compared with 25 percent of the untreated.

Interestingly, many of the boys in this study, whether steroid-treated or not, were smaller than average for their age and had bones that were abnormally narrow and below average in density, suggesting that other factors besides corticosteroids may influence the skeleton in DMD.

The investigators note, however, that osteoporosis (bone thinning) and damage to the bones are important considerations when corticosteroid treatment is undertaken. They prescribe calcium supplements for their patients and monitor them with bone density scans.

Velimir Matkovic, a physician in the Physical Medicine and Rehabilitation Department at OSU who was part of this study, now has an MDA grant to study skeletal development in boys with DMD and its relationship to steroid treatment.