Disease Information

What is Motor Neuron Disease?

Motor Neurone Disease (MND) is the name given to the group of diseases in which the motor neurones undergo degeneration and die. It goes under the umbrella of conditions termed neurodegenerative disorders. Motor neuron diseases cause the nerves in the spine and brain to lose function over time. They are a rare but severe form of neurodegenerative disease. Some MNDs are inherited, however most causes of most MNDs are not known. In sporadic or noninherited MNDs, environmental, toxic, viral, or genetic factors may be implicated.

MNDs are classified according to whether they are inherited or sporadic, and to whether degeneration affects upper motor neurons, lower motor neurons, or both. Common subtypes include

In adults, the most common MND is Amyotrophic lateral sclerosis (ALS), which affects both upper and lower motor neurons. It has inherited and sporadic forms and can affect the arms, legs, or facial muscles.
Primary lateral sclerosis (PLS) is a disease of the upper motor neurons
Progressive muscular atrophy (PMA) affects only lower motor neurons in the spinal cord
Progressive Bulbar Palsy (PBP), the lowest motor neurons of the brain stem are most affected, causing slurred speech and difficulty chewing and swallowing. There are almost always mildly abnormal signs in the arms and legs.
Kennedy’s disease, also known as progressive spinobulbar muscular atrophy
Post Polio Syndrome
Spinal muscular atrophy (SMA)

Symptoms of Motor Neuron Disease

The physical effects of motor neurone disease can include:

• Muscle aches, cramps, twitching
• Clumsiness, stumbling
• Weakness or changes in hands, arms, legs and voice
• Slurred speech, swallowing or chewing difficulty
  fatigue
• Muscle wasting, weight loss
• Emotional lability – for example, where a slight upset can cause an exaggerated response, such as crying or laughing
• Cognitive change (changes in thought processes)
• Respiratory changes.

It was thought that MND only affected the nerve cells controlling the muscles that enable people to move, speak, breathe and swallow. However, it is now known that up to 50 per cent of people with MND can experience changes in cognition, language, behaviour and personality. Most people experience relatively mild changes.

Causes of Motor Neuron Disease

The causes of MND are unknown, but worldwide research includes studies on:

• Exposure to viruses
• Exposure to certain toxins and chemicals
• Genetic factors
• Inflammation and damage to neurons caused by an immune system response
• Nerve growth factors
• Growth, repair and ageing of motor neurons.

Familial (hereditary) MND accounts for about five to 10 percent of cases. Several gene mutations have been identified since 1993, and current research aims to identify further genes linked to MND. The majority of cases, 90 to 95 per cent, are sporadic.

Diagnosing Motor Neurone Disease

Speak to your GP if you experience the initial symptoms of MND.

After hearing about your symptoms and an initial exam, your GP might refer you to a neurologist (a doctor who specialises in conditions affecting the brain and nervous system).

Diagnosing MND can be difficult during the early stages. This is because many of the first symptoms can be caused by other more common health conditions like:

• A trapped nerve – wear and tear of the bones in the spine can sometimes cause nerves to become trapped under the spine
• Peripheral Neuropathy – where part of the nervous system is damaged by another condition, like type 2 diabetes
• Swallowing difficulties caused by narrowing or inflammation of the gullet
• Speech difficulties due to problems with the voice box
• Damage to the brain by stroke or other neurological conditions like multiple sclerosis (MS) in younger people

Effects of MND

People who have MND may:

• Develop generalised paralysis (paralysis of both sides of the body)
• Lose speech and have difficulty swallowing
• Become breathless and experience sleep disturbance
• Experience mild cognitive and behavioural change
• Become increasingly dependent on others for all aspects of day-to-day activity.

Risk Factors of Motor Neurone Disease

• This occurs in adults or children, depending on the type.
  more likely to affect men than women.
• Inherited forms of the condition may be present at birthAgent Orange at Johnston Atoll 1976.jpg
• Most likely to appear after the age of 40 years, usually between 55–75 years.
• The various types may have different risk factors.
• SMA is always hereditary, but this is not true for all forms of MND.
• According to NINDS, around 10% of ALS cases in the United States are hereditary.
• Veterans appear to have a 1.5–2 times higher chance of developing ALS than non-veterans. This may indicate that exposure to certain toxins increases the risk of having ALS.
• A 2012 study Trusted Source found that footballers have a higher risk of dying from ALS,
• Alzheimer’s disease, and other neurodegenerative diseases, compared with other people. Experts think that this could indicate a link with recurrent head trauma

Reference:

https://www.physio-pedia.com/Motor_Neurone_Disease_MND

https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/motor-neurone-disease

https://www.nhsinform.scot/illnesses-and-conditions/brain-nerves-and-spinal-cord/motor-neurone-disease-mnd/