There are four main types of MND, each affecting people in different ways. There can be a great deal of overlap between all of these forms, so, while it is useful to separate the various types of the disease, in practise it is not always possible to be so specific.
We give brief definitions here, but further detail is provided under Information for download at the bottom of this page.
The following definitions talk about life expectancy, so you may not want to read any more at this stage.
Amyotrophic lateral sclerosis (ALS)
This is the most common form, with both upper and lower motor neurone involvement. This form of the disease is characterised by weakness and wasting in the limbs. Someone may notice they are tripping when walking or dropping things. Average life expectancy is from two to five years from onset of symptoms.
Progressive bulbar palsy (PBP)
Affects about a quarter of people diagnosed, and involves both the upper and lower motor neurones. Symptoms may include slurring of speech or difficulty swallowing. Life expectancy is between six months and three years from onset of symptoms.
Progressive muscular atrophy (PMA)
Affects only a small proportion of people, mainly causing damage to the lower motor neurones. Early symptoms may be noticed as weakness or clumsiness of the hand. Most people live for more than five years. An email support group exists for this rare form of MND.
Primary lateral sclerosis (PLS)
A rare form of MND involving the upper motor neurones only, causing mainly weakness in the lower limbs, although some people may experience clumsiness in the hands or speech problems. Life span could essentially be normal, although it may be life-limiting, depending on whether it remains as pure PLS or develops into ALS. An email support group exists for this rare form of MND.
Kennedy's Disease and MND have similar traits, which can cause confusion during diagnosis. Kennedy's Disease is a slowly progressive disorder of the motor neurones that is caused by a genetic mutation. It is a rare form of muscular atrophy leading to weakness. Although it is not classed as one of the types of MND, it is included in the conditions supported by the MND Association. It only affects men, but women may carry the mutation. It is possible through gene testing to determine an accurate diagnosis for Kennedy's Disease. The disease is compatible with a normal life span.