Résumé :
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Duchenne muscular dystrophy (DMD) is characterized by a progressive destruction and ultimate disappearance of the skeletal muscle parenchyma, which is replaced by adipose and fibrous connective tissue. Previous reports about the involvement of neuromuscular spindles in this pathological process were controversial, but were done mainly in young patients. Here, we report the case of a severely affected DMD patient, 27 years old, in which neuromuscular spindles were preserved in spite of the completely or almost completely disappearance of the extrafusal myofibers. Well-preserved neuromuscular spindles were observed in biopsies of the biceps brachii and a forearm muscle. The well-preserved intrafusal myofibers showed absence of dystrophin but also utrophin, evidencing that their preservation was not due to an over-expression of this last protein. To our knowledge, this is the first report of neuromuscular spindle preservation in a so old and severely affected DMD patient. It would be interesting to elucidate the mechanism by which intrafusal myofibers can be preserved in DMD, in spite of the completely destruction of the extrafusal myofibers. On the other hand, the fact that neuromuscular spindles can be preserved in severely affected DMD patients appears as important for the therapeutic possibility of restoring the lost myofibers by cell-based tissue-engineering strategies. We want to point-up that therapeutic strategies aiming to restore extrafusal myofibers in degenerating muscles may provide little benefit if the mechanisms of proprioception are not preserved.
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