What is Motor Neurone Disease?

Every day in the United Kingdom, six people are diagnosed with motor neurone disease (MND). At any one time, there are around 5,000 adults in the UK with the disease. Professor Stephen Hawking is a famous example of someone who lived with MND. However, his case is unusual in that he lived with the disease for over 50 years.

More often, this fatal disease kills people within a few years of diagnosis. A person’s average lifetime risk of developing MND is 1 in 300 people and those who are diagnosed are more likely to be male and aged between 50 and 70 years old.

What is motor neurone disease?

Motor neurone disease is fatal and progresses rapidly. It is a neurological disease which attacks the nerves in the body that control movement, meaning muscles no longer work. These nerves are called motor neurones and give the disease its name in the UK.

Motor neurones control activity in the muscles such as walking, speaking, gripping, breathing and swallowing by transmitting electrical signals. They pass messages to the next neurone by a chemical messenger that travels through the gap between one neurone and another. When the nerves are attacked by the disease, they gradually stop working because the nerves are unable to send messages to the muscles. At first, the muscles become weaker and lose muscle mass. However, eventually, the disease leads to breathing difficulties and full paralysis.

Given the disease affects motor neurones rather than sensory neurones, the senses and mental capacity are not normally affected by the disease. Those with the disease are therefore usually fully aware of their condition and their physical decline. Unfortunately, there is no cure for motor neurone disease and the average prognosis is around two years from diagnosis with around one-third dying within a year. Indeed, it is often known as the 1,000-day disease because most sufferers die within a thousand days of diagnosis.

How does motor neurone disease progress?

Motor neurone disease is always fatal. There is no cure. It is important to establish this from the outset. The disease will progress, but it does not always progress in the same way. Some people will experience a rapid progression of symptoms whereas for others it’s much slower.

The first stages

The first stages of the disease are often what trigger the first trip to the GP. Muscle weakness is a common first symptom and will result in a person becoming clumsier. They’ll perhaps stumble, trip or drop things more often.  They may drag a leg behind them when they walk or have ‘foot drop’ due to weaker ankle muscles.

Eventually, tasks of daily living become difficult or impossible without assistance. These symptoms are all related to progressive muscle weakness. The muscles will also eventually become stiffer which is sometimes painful. Most people who develop MND will need a wheelchair some months after their diagnosis.

Speaking and swallowing problems

A sign of the disease progressing in the most common trajectory of MND is developing difficulties talking and/or swallowing as the muscles in these areas deteriorate. Sometimes, people with MND experience choking regularly as a result and many opt for a gastrostomy tube. Most people retain some of their speech ability but for some, they lose it completely.

Excess saliva

The progression continues with the presence of excess saliva caused by the lack of ability to swallow. This means that the person can drool or experience pooling saliva in their mouth.

Yawning

Interestingly, the later stages of the disease cause a person to yawn excessively even if they are not tired. Due to stiffer facial muscles, yawning episodes can cause pain in the jaw. The episodes are also not controlled and can be problematic for the sufferer.

Emotions

The advanced stages of MND bring a whole host of emotions for all involved. However, for the MND sufferer, their emotional control can change significantly. They may cry uncontrollably at inappropriate moments or even laugh when they really shouldn’t.

Breathing problems

The later stages of MND mean that breathing becomes increasingly effortful. The muscles that support the diaphragm become weaker and breathing becomes more difficult. Many sufferers need assisted ventilation to remain alive.

Death and life expectancy

As mentioned, motor neurone disease is commonly called the 1,000-day disease due to its rapid progression. The life expectancy for those with the disease, however, is dependent on two areas: the motor neurones affecting the swallowing muscles, and those affecting the diaphragm and other muscles responsible for breathing. The majority of people dying from MND do so due to respiratory failure.

What causes motor neurone disease?

Scientists do not have all the answers when it comes to what causes motor neurone disease. Individuals are often affected by a different trigger in their genetic make-up and/or their environment.

Research into proteins within axons (nerve fibres) has shown their importance in maintaining motor neurones. This implies that a fault in maintaining these proteins could be partly to blame for the disease. Additionally, scientists have found that glutamate, a nerve cell messenger, is harmful when faced with too many messages. There is now a lot of evidence to suggest that glutamate is a destructive factor in MND.

MND mostly occurs without a genetic predisposition, meaning that those who suffer from it are usually the only person in their family with the condition. Some motor neurone disease types are hereditary, but most are sporadic. For hereditary types, there are usually mutations in a gene (the gene affected varies depending on the type of motor neurone disease inherited). However, only around 5%–10% of cases are inherited.

Researchers believe that a mix of factors and triggers usually bring about the onset of the disease. Environmental triggers could include food or drink in the person’s diet as well as things they breathe or touch. It could also be triggered by a combination of these. Rarely, there is a family history of the disease, and its cause is linked to a genetic mutation. Quite often, an environmental trigger is thought to activate the disease.

Some studies have found that some possible links with the development of MND include:

• Those who exercise intensely.
• Military service personnel.
• Those who’ve experienced mechanical trauma.
• Those who’ve suffered electrical trauma.
• Exposure to chemicals used in agriculture.
• Exposure to some heavy metals.
• Diet.

That said, no clear conclusions have been drawn. As such, it is difficult to predict a person’s risk of developing MND.

Who is more at risk of motor neurone disease?

Motor neurone disease is fairly uncommon. It can affect anyone of any age but those who are more likely to be affected are those in their 60s or 70s. However, there are some other risk factors too. Men are twice as likely to develop MND compared to women. Despite the risk factor being around 1 in 300 developing a form of MND in their lifetime, the prevalence of the disease in the UK is fairly low, with around 5,000 living with the disease at any one time.

According to Dr Johnathan Cooper-Knock, a researcher at the University of Sheffield, “the numbers of high-profile athletes affected with MND is not a coincidence.” His research showed that those whose DNA predisposes them to want to do more strenuous exercise had a higher chance of getting MND. Having said that, Dr Cooper-Knock was adamant that stopping exercising was not the answer to lowering one’s risk of developing MND and that doing so would “do more harm than good”.

What are the signs and symptoms of motor neurone disease?

Motor neurone disease affects people in different ways.

However, there are usually some common symptoms including:

• Limb weakness, including tripping more easily.
• Progressive loss of movement in the limbs.
• Weight loss due to muscle atrophy (loss of muscle mass).
• Fasciculations – Rippling sensations or twitching felt under the skin.
• Muscle cramps and tightness, which can also be painful.
• Breathing problems.
• Extreme fatigue.
• Speech difficulties.
• Swallowing difficulties.

Often, the muscles in the feet, mouth or hands are the first to be affected. However, the onset is usually gradual and does not start in each muscle area at the same time.

Other less common symptoms include behavioural or cognitive changes. Normally, these changes are only slight. However, rarely, a few sufferers will experience frontotemporal dementia (FTD) and will need extra care and support. Those with MND also experience heightened emotions that are often unexpected. They may laugh when they’re feeling sad or cry when they’re feeling happy. The term for this symptom is emotional lability and it is confusing and distressing for the sufferer.

Thankfully, MND does not normally affect some parts of the body including the senses, bowel and bladder functions, and sexual function. However, other symptoms of the disease may make these functions more difficult.

What are the different types of motor neurone disease?

The most common form of motor neurone disease is called amyotrophic lateral sclerosis (ALS) which is also the umbrella term used to describe the condition in the US. ALS exhibits with muscle wasting in the limbs with associated weakness, muscle cramps and stiffness. People with ALS also tend to drop things or trip up when in the early stages of the disease.

Progressive bulbar palsy (PBP) is another form of MND. This subtype affects fewer people and is more apparent in the face muscles, throat and tongue in the early stages. Those with PBP may first notice that they have difficulty swallowing or slurred speech.

The third type of MND is progressive muscular atrophy (PMA) and this is also much less common than ALS. Those with this type of MND may first develop reduced reflexes and reduced dexterity in their hands. They also experience generalised weakness.

The fourth type of MND is primary lateral sclerosis (PLS). This type of MND usually progresses more slowly than other forms of the disease. The lower limbs are often the first part of the body affected with sufferers experiencing generalised weakness. They often also experience a loss of dexterity or clumsiness in the hands as well as speech difficulties.

How is motor neurone disease diagnosed?

MND is a difficult disease to diagnose for a few reasons. Firstly, not many people have motor neurone disease, and the early symptoms of the disease can also be symptoms of other conditions. These symptoms include weakness, slurred speech and/or clumsiness. Many people live with such symptoms for a while before going to see their doctor.

Motor neurone disease is almost always diagnosed by a neurologist – an expert in the brain and nervous system. Those with neurological problems usually undergo lots of tests including nerve conduction studies and blood tests to rule out other conditions and diseases.

How is motor neurone disease treated?

Given the bleak outlook of the disease, it is no surprise to most that there is no cure. Any treatment for the disease is palliative and aims to compensate for the person’s loss of function in their mobility, swallowing, breathing and communication. As such, the goal is to make the person as comfortable as possible and allow them the best possible quality of life.

Such treatment may include:

• Occupational therapy to help with tasks of daily living.
• Physiotherapy to help reduce stiffness and maintain strength for as long as possible.
• Speech and language therapy support.
• Dietetic support.
• Emotional support for the patient and their family.

Those with MND may be fitted with a feeding tube (gastrostomy) to allow them to maintain nutrition when they are too weak to eat, drink and swallow. There is also the option of administering medication to reduce excessive drooling. Some experts are working on producing other medications that may reduce symptoms and improve a patient’s life expectancy. A medicine called Riluzole is one such medication that has shown a small improvement, but it does not stop the progression of the disease.

Riluzole

This is the only known medication at the moment that has had a positive survival benefit on those with motor neurone disease. It has shown that it slows down the damage to motor neurones as it reduces their sensitivity to glutamate, the nerve transmitter.

Research has shown that the drug has extended a person’s survival by an average of two to three months, but this varied. There are some side effects of the drug, but these are usually mild.

Setting up an advance decision

For those recently diagnosed with MND, many draw up a plan called an advance decision or advanced directive. This is where the patient makes known their treatment preferences for when they cannot communicate such preferences later because of their deterioration.

An advance decision may include:

• How the person wants to spend their final stages. This may be that they would prefer to be at home, in a hospice or in a hospital.
• The types of medication that the person would be happy to take if the need arose.
• Whether a feeding tube is considered when they lose their ability to swallow.
• Whether they wish to be resuscitated in the case of respiratory failure and/or whether they would want to be fitted with a tracheostomy and ventilator.
• Whether they would consider donating organs for research after they die.

Final thoughts on, What is Motor Neurone Disease?

Motor neurone disease is one of a few diseases that is always fatal and has no known cure. Researchers are working hard on developing treatments that may one day lead to a cure. At present, that is out of reach and, unfortunately, for those already diagnosed, time is already running out.

According to Emma Moss, a former deputy head teacher and MND sufferer, “the message you get when you are diagnosed is you have two to five years, go and get on with what you have left of your life.” Emma and other MND sufferers are determined to change that message and offer hope and possibility. She helped to campaign for increased investment into MND research in 2021 with the government agreeing to fund £50m over the next five years. The hope is that it will bring more treatment options for those living with the disease.

Fortunately, there are lots of places that offer specialist support for those with motor neurone disease and their families:

• MND Support Line.
• MND Scotland.
• MND Association.
• Challenging MND.
• Brain Research UK.