Motor neurone disease (MND) is the name given to a group of diseases in which the nerve cells - neurones - controlling the muscles that enable us to move, speak, breathe and swallow; undergo degeneration and die.
Neurones are nerve cells. Motor neurones take messages from the brain to the voluntary muscles and to some glands. There are two types of motor neurones. Upper motor neurones (UMN) take the messages from the brain through the spinal cord. Lower motor neurones (LMN) take the message from the spinal cord to the muscles.
MND leads to the degeneration of these motor neurones. It can affect:
- just the upper motor neurones in the brain that descend to the spinal cord or,
- just the lower motor neurones that exit the spinal cord to activate muscles or,
- both upper and lower motor neurones.
With no nerves to activate them, muscles gradually weaken and waste. The patterns of weakness vary from person to person.
MND does not affect the sensory neurones – the nerves that receive messages from things we see, touch, smell, hear and taste.
Motor neurone disease occurs at similar rates in most countries of the world. It is estimated that there are presently around 400,000 people worldwide diagnosed with MND and about 2000 people with MND in Australia. Slightly more men than women are diagnosed with MND, most commonly in the 50 to 60 year age group. However, MND may be diagnosed in adults at any age.