progressive muscle atrophy is called
ALS is a progressive, degenerative disease of the nervous system. It is one of a group of diseases, called motor neuron diseases (MND), in which specialized nerve cells that control movement of the voluntary muscles gradually cease functioning and die. Fasciculation is a sign of muscle irritability, as the normal action of the lower motor neuron on the muscle is impaired. 2  The sole involvement of lower motor neurons can be seen in a form of ALS called progressive muscular atrophy.