What is motor neurone disease (MND)?
Variants of MND
The term “motor neurone disease” refers to a group of related conditions that affect motor nerves. While they share similarities, they can present in different ways and progress differently from person to person.
You don’t need to memorise each variant, but it’s helpful to have basic awareness of how MND can vary.
Click the arrows below to reveal more information about the variants of MND.
Amyotrophic Lateral Sclerosis (ALS)
- Most common form of MND
- Involves both upper and lower motor neurones
- Can start in the limbs, bulbar region (speech/swallowing), or rarely around the shoulders
- Symptoms include muscle weakness, wasting, stiffness, and reflex changes
- Progression and survival vary — average survival is 2–5 years
- Faster progression often seen with bulbar onset or cognitive impairment
Primary Lateral Sclerosis (PLS)
- Rare form, affecting fewer than 3% of people with MND
- Affects only upper motor neurones
- Symptoms include stiffness (spasticity), usually beginning in the legs
- Often slow progression and long survival — usually not life-shortening
- May resemble hereditary spastic paraplegia (HSP)
Progressive Bulbar Palsy (PBP)
- Starts with speech and swallowing difficulties
- May also involve emotional lability (e.g. sudden laughing or crying)
- Often progresses to affect the limbs
- Can involve both upper and lower motor neurones
Progressive Muscular Atrophy (PMA)
- Accounts for 5–10% of MND cases
- Involves only lower motor neurones
- Causes muscle wasting, weakness, and visible fasciculations
- Usually begins in the limbs, especially upper limbs
- Includes “Flail Arm Syndrome” — a slower progressing form with shoulder/arm weakness