Duchenne muscular dystrophy (DMD) is characterised by the absence of dystrophin in muscle biopsies, although residual dystrophin can be present, either as dystrophin-positive (revertant) fibres or traces. As restoration of dystrophin expression is the end point of clinical trials, such residual dystrophin is a key factor in recruitment of patients and may also confound the analysis of dystrophin restoration in treated patients, if, as previously observed in the mdx mouse, revertant fibres increase with age. In 62% of the diagnostic biopsies reports of 65 DMD patients studied, traces or revertants were recorded with no correlation between traces or revertants, the patients' performance, or corticosteroids response. In nine of these patients, there was no increase in traces or revertants in biopsies taken a mean of 8.23 years (5.8-10.4 years) after the original diagnostic biopsy. This information should help in the design and execution of clinical trials focused on dystrophin restoration strategies.
Scoliosis affects 75 to 90% of patients with non-ambulant Duchenne muscular dystrophy (DMD). Spinal surgery is the treatment of choice but the indication varies among centres. Some offer surgery to all non-ambulant patients, irrespective of scoliosis severity. Early surgery has the advantage of targeting DMD when cardiorespiratory function is preserved, but not all patients develop scoliosis. We report our 10-year experience of scoliosis management in 123 patients with DMD who were at least 17 years old at the time of the study. Scoliosis was absent in 10%, and mild, non-progressive (at least 30 degrees ) in 13% of patients. Another 13% had moderate scoliosis (31-50 degrees ) and were managed conservatively. Surgery was considered in 57% (70/123) of patients with scoliosis greater than 50 degrees and eventually performed in 35%. The remaining patients either refused surgery (9%) or were unfit because of cardiorespiratory compromise (13%). In a further 7%, scoliosis (greater than 50 degrees ), first noted after 14 years of age, was progressing slowly and surgery was not performed. At 17 years there was no difference in survival, respiratory impairment, or sitting comfort among patients managed conservatively or with surgery. One-third (44/123) of our patients were managed satisfactorily without receiving spinal surgery. We provide insight into the natural history of scoliosis in DMD that should help families and clinicians with decision-making when surgery is considered.
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