<unk> s or<unk> s <unk> s) are a group of rare neurodegenerative disorders that selectively affect<unk>  neurons, the cells which control voluntary muscles of the body. They include amyotrophic lateral sclerosis (ALS), progressive bulbar palsy (PBP), pseudobulbar palsy, progressive muscular atrophy (PMA), primary lateral sclerosis (PLS), spinal muscular atrophy (SMA) and monomelic amyotrophy (MMA), as well as some rarer variants resembling ALS.<unk> s affect both children and adults. While each<unk>  affects patients differently, they all cause movement-related symptoms, mainly muscle weakness. Most of these<unk> s seem to occur randomly without known causes, but some forms are inherited. Studies into these inherited forms have led to discoveries of various genes (e.g. SOD1) that are thought to be important in understanding how the<unk>  occurs. Symptoms of<unk> s can be first seen at birth or can come on slowly later in life. Most of these<unk> s worsen over time; while some, such as ALS, shorten one's life expectancy, others do not. Currently, there are no approved treatments for the majority of<unk>  neuron disorders, and care is mostly symptomatic.
Motor neuron disease
Vascular myelopathy
Polyneuropathy
Basal ganglia disease
Upper motor neuron syndrome
Distal hereditary motor neuronopathies
Tropical ataxic neuropathy
Amyotrophic lateral sclerosis