Types of MND

Motor neurone disease can be classified into four main types depending on the pattern of motor neurone involvement and the part of the body where the symptoms begin. There can be an overlap between all of the different types so, while it is useful to classify the various types of the disease, in practice it is not always possible to be so specific.

Amyotrophic lateral sclerosis (ALS)

ALS is the most common type of MND, with both upper and lower motor neurone involvement. ALS is characterised by muscle weakness and stiffness, over-active reflexes and, in some cases, rapidly changing emotions. Initially the limbs cease to work properly. The muscles of speech, swallowing and breathing are usually also later affected.

Progressive bulbar palsy (PBP)

Mixed bulbar palsy and pseudo-bulbar palsy are forms of progressive bulbar palsy that involve the muscles of speech and swallowing. The nerves that control these functions are located in the bulb (the lower part of the brain), hence the term bulbar palsy (paralysis). The limb muscles may also later be affected. PBP affects about a quarter of people diagnosed, and involves both the upper and lower motor neurones.

Progressive muscular atrophy (PMA)

Progressive muscular atrophy affects only a small proportion of people, and has a slower rate of progression and longer survival compared to ALS and PBP types. It mainly causes damage to the lower motor neurones. Early symptoms may be noticed as weakness or clumsiness of the hand. Characterised by absent reflexes, muscle wasting and weakness.

Primary lateral sclerosis (PLS)

PLS is 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 is usually more than 10 years from onset of symptoms, although in some cases PLS develops into ALS. Diagnosis is often provisional.

The Genetic Health Service NZ sees people where a mutation is already identified in their family, or to assess a family that has not had any testing. Testing needs to start in a family member with a clinical diagnosis of MND or dementia, as this gives the most information for a family.