There are different forms of motor neurone disease. The three main forms are amyotrophic lateral sclerosis (ALS), progressive muscular atrophy (PMA), and progressive bulbar palsy (PBP). Each form is named according to the pattern of symptoms it presents. The most common form is ALS (also known as Lou Gehrig's disease). A fourth form of the disease, primary lateral sclerosis (PLS), is rare and often only provisionally diagnosed.
Most cases of motor neurone disease occur randomly, with no known cause. However, 5–10% of people will have a family history of the disease, suggesting a genetic link in those cases.
Motor neurone disease is most commonly diagnosed in those over the age of 40 years, occurring mainly in those aged between 50 and 70 years. In some cases, though, symptoms can first appear in a person's 20s.
Usually the onset of motor neurone disease is gradual but younger patients may show a more rapid progression. The average life expectancy is 2–4 years from diagnosis but some people succumb within a matter of months, while others live up to 20 years or (in rare cases) beyond. Famous theoretical physicist Stephen Hawkings defied the odds for 55 years following his ALS diagnosis in 1963 until his death in 2018.
Signs and symptoms
Initial symptoms depend on the form of the condition. However, the most common early sign is weakness in the arms and legs. This is often more pronounced on one side than the other. Other early signs of the condition include:
- Muscle twitching
- Muscle wasting
- An increasingly stiff, clumsy walk
- General fatigue
- Difficulty with chewing, swallowing and speech.
- Use their hands and arms
- Speak clearly, or at all
- Hold up their head.
Pain may be experienced. Musculoskeletal pain, pressure associated with immobility and muscle cramps are the most common causes of pain. Motor neurone disease does not affect touch, sight, smell, hearing, or intellect. Additionally, the muscles that move the eyes are usually not affected.
Management of the condition will require input from a team of health professionals that may include:
- Family doctor
- Respiratory specialist
- Occupational therapists
- Speech and language therapists
- Nurse specialists and district nurses
- Social workers
- Palliative care specialists and hospice care
- Sleep technologists.
The progressive nature of the condition means that most people will eventually require full time nursing care. When breathing becomes too difficult, a mechanical ventilator may be required to maintain breathing. While the use of a ventilator can prolong life and improve sleep, it will not alter the course of the condition, and many people with motor neurone disease therefore choose not to use ventilators for lengthy periods.
Support and information
O’Toole, M.T. (Ed.) (2017). Amyotrophic lateral sclerosis (ALS). Mosby’s Dictionary of Medicine, Nursing & Health Professions (10th ed.). St Louis, MI: Elsevier.
MND New Zealand (2018). MND: Some facts (Booklet). Auckland: Motor Neurone Disease Association of New Zealand. http://mnda.org.nz/about-mnd/
National Institute of Neurological Disorders and Stroke (2019. Motor Neuron Diseases Information Page (Web Page). Bethesda, MD: National Institutes of Health Neurological Institute. https://www.ninds.nih.gov/Disorders/All-Disorders/Motor-Neuron-Diseases-Information-Page#disorders-r1 [Accessed: 22/07/19]
NHS (2018). Motor neurone disease (Web Page). Redditch: National Health Service (NHS)
England. https://www.nhs.uk/conditions/Motor-neurone-disease/ [Accessed: 22/07/19]PHARMAC (2013). Approval of proposal to fund riluzole for amyotrophic lateral sclerosis (motor neurone disease), 11 September 2013 (Web Page). Wellington: Pharmaceutical Management Agency. https://www.pharmac.govt.nz/news/notification-2013-09-11-riluzole/ [Accessed 22/11/16]