Motor neurone disease symptoms can include generalised muscle spasms, exaggerated reflexes and a progressive wasting and weakness of muscles responsible for speech, chewing and swallowing. As the condition progresses, sufferers may be unable to walk, speak, use their arms and hands, or hold up their head.
Most cases of motor neurone disease occur randomly, with no known cause. However, 5 - 10% 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, and has its highest incidence in those aged between 50 and 70 years. In some cases, though, symptoms can first appear in a person's 20s.
Usually the onset is gradual but younger patients may show a more rapid progression. The average life expectancy is two to four years from diagnosis but some people succumb within a matter of months, while others live up to 20 years.
Signs and symptoms
Initial symptoms will 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
As the condition progresses, motor neurone disease sufferers may not be able to:
- Use their hands and arms
- Speak clearly, or at all
- Hold up their head
Pain is experienced in about 40% of cases. 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.
A common test used in the diagnostic process is an electromyogram (EMG) which is an electrical test of muscle function. Another common test is a nerve conduction study (NCS) which assesses a nerve's ability to send a signal. Other tests that may be used to assist with the diagnosis and rule out other causes for the symptoms include:
- Blood and urine tests
- Computerised tomography (CT) or magnetic resonance imaging (MRI) scans
- Muscle biopsy – to determine the health of the muscle tissue
A disease-modifying drug called riluzole (Rilutek), which has the potential to modestly prolong survival in some patients, is available in New Zealand.
Management of the condition will require input from a multi-disciplinary group of health professionals that may include:
- Family doctor and medical specialists (neurology, respiratory, sleep, gastroenterology)
- 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.) (2013). Motor neuron disease. Mosby’s Dictionary of Medicine, Nursing & Health Professions (9th ed.). St Louis: Elsevier Mosby.
O’Toole, M.T. (Ed.) (2013). Amyotrophic lateral sclerosis (ALS). Mosby’s Dictionary of Medicine, Nursing & Health Professions (9th ed.). St Louis: Elsevier Mosby.
MedicineNet.com (Publication date not stated). Amyotrophic lateral sclerosis (ALS or “Lou Gehrig’s disease) [Web Page]. San Clememte, CA: MedicineNet, Inc. [Accessed: 22/11/16]
Motor Neurone Disease Association of New Zealand (2012). About MND (Web Page). Auckland: Motor Neurone Disease Association of New Zealand. http://mnda.org.nz/about-mnd/ [Accessed: 22/11/16]
National Institute of Neurological Disorders and Stroke (2013). Amyotrophic lateral sclerosis – Fact sheet (Web Page). Bethesda, MD: National Institutes of Health Neurological Institute. http://www.ninds.nih.gov/disorders/amyotrophiclateralsclerosis/detail_amyotrophiclateralsclerosis.htm [Accessed: 22/11/16]
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]
Veale, A. (2009). Respiratory and sleep physician. Personal communication.