Motor neuron diseases (MND) are a group of progressive neurological disorders that cause the degeneration and death of motor neurons, which are responsible for controlling voluntary muscle movement. This leads to muscle weakness, atrophy, and eventually paralysis. Common types of MND include amyotrophic lateral sclerosis (ALS), progressive bulbar palsy (PBP), primary lateral sclerosis (PLS), and spinal muscular atrophy (SMA).