ALS/MND Definitions

Last Updated: August 14th, 2009

The following definitions serve as a glossary of terms for individuals affected by ALS and motor neuron disease. If you have a definition or resource you would like to add please contact us at info(@)alsforums.com.

We have added the following definitions resource available in three categories for brevity:

ALS - Amyotrophic Lateral Sclerosis

Pronunciation: a-my-o-tro-phic lat-er-al scle-ro-sis

What is Amyotrophic Lateral Sclerosis?
Amyotrophic Lateral Sclerosis (ALS) is often referred to as Lou Gehrig's Disease. ALS is a progressive and fatal neuromuscular disease.

Individuals living with Lou Gehrig's disease are affected by a gradual degeneration of nerve cells in their central nervous system.

The degeneration of nerve cells leads to an inability to control their voluntary muscles - including motor skills with their hands, feet, arms, legs and life sustaining functions such as swallowing.

As the disease progresses muscles become weaker. The disorder causes muscle weakness and atrophy, usually resulting in death within five years of onset.

MND - Motor Neuron Disease (North America)

MND - Motor Neurone Disease (UK)

Pronunciation: motor neu-ron disease

What is Motor Neuron Disease?

Motor neurone disease (MND) is a progressive neuro-degenerative disease that attacks the upper AND lower motor neurons. Motor neurone disease is a chronic and slowly progressive disease marked by the wasting of muscles and associated with weakness and paralysis.

Degeneration of the motor neurons and the resulting weakness causes increased loss of mobility in the limbs, difficulty with speech, swallowing, and breathing.

MND is an international term that covers a number of illnesses that fall under the degenerative motor neurone diseases, including: amyotrophic lateral sclerosis (ALS), progressive muscular atrophy (PMA), progressive bulbar palsy (PBP), and primary lateral sclerosis (PLS).

Motor Neuron

Pronunciation: motor neu-ron

What is a motor neuron?

A motor neuron, also called a motoneuron, is a nerve cell (neuron) that begins in the cortex of the brain and send signals to and from muscles.

Neurodegenerative

Pronunciation: neu-ro-de-gen-er-a-tive

What is neurodegenerative?
Neurodegenerative refers to the progressive, ongoing loss of neurologic functions. This loss of function happens in all forms of motor neuron disease. The acceleration of loss depends on the diagnosis of the disease. Amyotrophic lateral sclerosis is the the most rapidly progressing.

Neuron

Pronunciation: neu-ron

What is a neuron?
A neuron is a nerve cell that has the ability to send and recieve messages (in the form of electrical signals) throughout the human body.

PBP - Progressive Bulbar Palsy

Pronunciation: progressive bull-bar palsy

What is PBP?
Progressive bulbar palsy is a condition that starts with difficulties speaking, chewing and swallowing. These functions are interrupted because the individual's lower motor nerve cells undergo deterioration.

Facts: Approximately 20% of ALS patients suffer from progressive bulbar palsy.

PLS - Primary Lateral Sclerosis

Pronunciation: primary lat-er-al scle-ro-sis

What is Primary Lateral Sclerosis?
Primary Lateral Sclerosis is a progressive neuromuscular disease.

Primary lateral sclerosis is thought to be sporadic, however, there are familial forms of PLS that are hereditary, although rare. PLS is the name for a rare group of neurodegenerative disorders and is grouped under motor neuron disease.

Neurodegenerative disorders are caused by the degeneration of the upper motor neurons in the spinal cord and brain. People with PLS have less control of their voluntary muscles, including increased spasticity and weakness of voluntary muscles. PLS, while debilitating, is not normally fatal.

For more information about PLS refer to our general ALS and MND terms section, specifically this page: What is primary lateral sclerosis?

PMA - Progressive Muscular Atrophy

What is Progressive Muscular Atrophy?
Progressive muscular atrophy, like it's name suggests, is a progressive neurological disease in which the lower motor neurons begin to deteriorate. If the upper motor neurons are not affected within two years, the disease usually remains a lower motor neuron disease. (ALS affects both upper and lower neurons).

SMA - Spinal Muscular Atrophy

What is Spinal Muscular Atrophy?
Spinal muscular atrophy encompasses a number of disorders with genetic similarities and the presence of weakness from the loss (deterioration) of motor neurons in the brainsetm and/or spinal cord. Onset of SMA is sudden and progresses quickly. There is no known cure for SMA and the disease can be fatal.

Upper Motor Neuron

Pronunciation: upper motor neu-ron

What is an upper motor neuron?

An upper motor neuron is a neuron that starts in the motor cortex of the brain and terminates at the spinal cord or within the medulla.