What is progressive muscular atrophy (PMA)?

Progressive muscular atrophy (PMA) is a variant of ALS that was described by the French neurologist François Aran as early as 1850. PMA is a degenerative disease of the second motor neuron in which muscle wasting (muscle atrophy) and muscle weakness (paresis) occur in a progressive manner. There is no damage to the first motor neuron – increased muscle reflexes (hyperreflexia) and muscle stiffness (spasticity) do not occur. PMA affects around 10 % of all people with ALS.