ESPE Abstracts

Background: Dystrophinopathies, including Duchenne (DMD) and Becker (BMD) muscular dystrophy, are X-linked muscle wasting disorders caused by mutations in the dystrophin gene. Dystrophin deficiency compromises functional integrity of the muscle fibers leading to progressive weakness, accompanied by a gradual bone loss.

Objective and hypotheses: This study’s goal was to evaluate the effect of whole body low magnitude vibration (WBLMV) on timed motor performance and bone health. The hypothesis was that WBLMV would stabilize muscle function and prevent bone loss in patients with dystrophinopathies.

Method: This pilot study included 3 DMD (5.9; 7.5; 12.5 years old) and 2 BMD (16.4 and 21.7 years old) boys, all ambulatory (able to walk ≥75 m unassisted). Each patient was given a Marodyne Low Intensity Vibration plate with an oscillating frequency of 30–90 Hz for daily use at home for 10 consecutive min/day for 6 months. Baseline measurements were taken twice within two weeks before treatment began, then at 6 months and 12 months, and included 6 min walk distance, 10 m walk, ‘stair climb’ test, ‘supine to stand’ test and peripheral quantitative computed tomography (pQCT) of the tibia (3% and 38% sites) to evaluate trabecular and cortical bone. Statistical analyses used mixed linear models to account for correlation of measurement times within subject.

Results: Motor function remained stable during the 6 months of intervention with WBLMV, followed by deterioration during the subsequent 6 months without WBLMV in a ‘stair climb’ test (73% slower at 12 mo vs 6 months, P<0.0001) and ‘supine to stand’ test (74% slower at 12 mo vs 6 months, P=0.027). There was a trend toward an increase in trabecular cross-sectional area during the intervention phase (680 vs 544 mm² at 6 mo vs baseline, respectively, P=0.069). Other indices of bone geometry did not change significantly.

Conclusion: WBLMV was well tolerated and appeared to have a positive effect on stabilizing muscle function and possibly bone health in patients with dystrophinopathies.