Motor neuron disease

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Motor neuron disease
Classification and external resources
Polio spinal diagram.PNG
spinal diagram
ICD-10 G12.2
ICD-9 335.2
DiseasesDB 8358
MeSH D016472

Motor neuron disease (MND) are a small group of neurological disorders that selectively affect motor neurons, the cells that control voluntary muscle activity including speaking, walking, swallowing, and general movement of the body. They are generally progressive in nature, and cause increasing disability and, eventually, death.

Motor neuron disorders or motor neuron diseases are a larger group of disorders that include any disease that affects neurons.[1]


The term motor neuron disease is used inconsistently. Some use it to refer to a group of diseases which includes amyotrophic lateral sclerosis (ALS) and others use it to specifically mean ALS.[2] The other four motor neuron diseases are: primary lateral sclerosis, progressive muscular atrophy, progressive bulbar palsy and pseudobulbar palsy.[2] To avoid confusion, the annual scientific research conference dedicated to the study of MND is called the "International ALS/MND Symposium".[citation needed]

While MND refers to a specific subset of similar diseases, there are numerous other diseases of motor neurons that as a group are referred to as motor neuron disorders.[1] Example include spinal muscular atrophy, spinobulbar muscular atrophy, Charcot–Marie–Tooth disease, Guillain–Barré syndrome, and many others.


In the most common classification, the term "motor neuron disease" applies to the following five disorders which affect either upper motor neurons (UMN) or lower motor neurons (LMN), or both:

Type UMN degeneration LMN degeneration
Amyotrophic lateral sclerosis (ALS) yes yes
Primary lateral sclerosis (PLS) yes no
Progressive muscular atrophy (PMA) no yes
Progressive bulbar palsy (PBP) no yes – bulbar region
Pseudobulbar palsy yes – bulbar region no

Even though diseases known as spinal muscular atrophies, including the most common spinal muscular atrophy (SMA), affect motor neurons and are classified as MND by the disease terminology classification system Medical Subject Headings (MeSH), they are not classified as such by the tenth International Statistical Classification of Diseases and Related Health Problems (ICD-10) published in 1992 and thus are not discussed in this article.


  1. ^ a b Ellison, edited by Seth Love, David N. Louis, David W. (2008). Greenfield's neuropathology (8th ed. ed.). London: Hodder Arnold. p. 947. ISBN 9780340906811. 
  2. ^ a b "Motor Neuron Diseases Fact Sheet: National Institute of Neurological Disorders and Stroke (NINDS)". Retrieved 7 November 2010. 

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