Progressive muscular atrophy

Progressive muscular atrophy
Classification and external resources
ICD-9-CM	335.21
DiseasesDB	29149
MeSH	D009134
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Progressive muscular atrophy (PMA), also known as Duchenne-Aran muscular atrophy and by various other names, is a rare subtype of motor neuron disease (MND) that affects only the lower motor neurons. PMA is thought to account for around 4% of all MND cases. This is in contrast to amyotrophic lateral sclerosis (ALS), the most common form of MND, which affects both the upper and lower motor neurones, or primary lateral sclerosis, another rare MND variant, which affects only the upper motor neurons. The distinction is important because PMA is associated with a better prognosis than classic ALS.

Despite being rarer than ALS, PMA was described earlier, when in 1850 French neurologist François Aran (English /ɑːˈrɑːn/) described 11 cases which he termed atrophie musculaire progressive. Contemporary neurologist Guillaume-Benjamin-Amand Duchenne de Boulogne English /duːˈʃɛn/ also claimed to have described the condition 1 year earlier, although the written report was never found. The condition has been called progressive muscular atrophy (PMA), spinal muscular atrophy (SMA), Aran–Duchenne disease, Duchenne–Aran disease, Aran–Duchenne muscular atrophy, and Duchenne–Aran muscular atrophy. The name "spinal muscular atrophy" is ambiguous as it refers to any of various spinal muscular atrophies, including the autosomal recessive spinal muscular atrophy caused by a genetic defect in the SMN1 gene.

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