Motor neurone disease is a rare condition that progressively damages the nervous system, causing the muscles to waste away.

Motor neurone disease occurs when specialist nerve cells, called motor neurones, stop working properly. Motor neurones control important muscle activity such as:

• walking
• speaking
• breathing
• swallowing

As the condition progresses, people with motor neurone disease will find these activities increasingly difficult, and eventually impossible, to do.

Exactly what causes the motor neurones to stop working properly is unclear, but several theories have been suggested.

Find out about the possible causes of motor neurone disease.

In its early stages, motor neurone disease causes symptoms such as:

• a weakened grip, which can cause difficulty picking up or holding objects
• a general feeling of tiredness
• muscle pains and cramps

As the damage progresses, the symptoms become more debilitating. In the final stages, a person with the condition will be unable to move their body (the medical name for this is total body paralysis) and their breathing difficulties will get worse.

Read more about the symptoms of motor neurone disease.

Treating motor neurone disease

There's currently no cure for motor neurone disease. Treatment aims to:

• make the person feel as comfortable and have the best quality of life as possible
• compensate for the progressive loss of bodily functions such as swallowing and breathing

For example, breathing masks and feeding tubes can help with breathing and swallowing difficulties, at least in the short to medium term.

A medication called riluzole can extend the lifespan of some people with motor neurone disease, but it's only moderately effective. Most people being treated would only live 3–6 months longer than otherwise expected.

Read more about the treatment of motor neurone disease.

Who is affected by motor neurone disease?

Motor neurone disease is a rare condition.

Most cases first develop in people in their late 50s or early 60s. Motor neurone disease is slightly more common in men than women.

In around 10% of cases, the person has a family history of motor neurone disease. This is known as familial motor neurone disease.

This type of motor neurone disease usually develops earlier when a person is in their late 40s or early 50s.

Types of motor neurone disease

There are three main types of motor neurone disease, which have similar symptoms but progress in different ways:

• Limb-onset disease begins with symptoms that affect the arms and legs, such as muscle weakness and loss of function. This is the most common type and accounts for 70% of cases.
• Bulbar-onset disease begins with symptoms that affect the mouth and throat, such as difficulties swallowing and slurred speech. This accounts for around 25% of cases.
• Respiratory-onset disease begins with symptoms that affect the lungs, such as shortness of breath. This accounts for around 5% of cases.

Survival rates

The outlook for motor neurone disease is very poor:

• People with limb-onset motor neurone disease will live for 3–5 years after their symptoms start.
• People with bulbar-onset and respiratory-onset motor neurone disease will live for 2–3 years after their symptoms appear.

People with some other less common types of motor neurone disease would be expected to live for up to 10 years. Some people have lived for several decades. The most famous example is the British physicist Stephen Hawking, who was diagnosed with motor neurone disease over 40 years ago.

Living with motor neurone disease can be frustrating, challenging and sometimes a terrifying possibility, but it's not necessarily as bleak as many people imagine. With treatment and support, many people lead a relatively independent lifestyle and enjoy a reasonably good quality of life.

However, once the breathing difficulties reach a certain stage, the body becomes starved of oxygen and the person with motor neurone disease will die.

Contrary to some reports, most people with motor neurone disease die painlessly and comfortably in their sleep. 

The symptoms of motor neurone disease usually follow a pattern that falls into three stages:

• the initial stage
• the advanced stage
• the end stage

Initial symptoms

The initial symptoms of motor neurone disease usually develop slowly and subtly over time. It can be easy to mistake early symptoms for those of several unrelated conditions that affect the nervous system.

Limb-onset disease

The initial symptoms of limb-onset motor neurone disease include:

• a weakened grip, which can cause difficulties picking up or holding objects
• a general feeling of tiredness
• muscle pains and cramps
• muscle twitches
• weakness in the arms or legs
• a feeling that you have become much more clumsy than usual, such as always tripping over

Bulbar-onset disease

The most common initial symptom of bulbar-onset disease is that your speech is increasingly slurred as you can't control your tongue properly.

Your tongue may become noticeably smaller and start to twitch.

As the condition progresses, speech problems become significantly worse and you'll also have difficulties swallowing. The medical term for swallowing difficulties is dysphagia.

Respiratory-onset disease

In some cases of respiratory-onset motor neurone disease, the initial symptoms are obvious, such as breathing difficulties and shortness of breath.

In other cases, the symptoms are less noticeable, such as waking up frequently during the night because your body is temporarily starved of oxygen when lying down.

This in turn can make you feel very tired the next morning. You may also wake up early in the morning with a headache.

Advanced symptoms

As motor neurone disease progresses to an advanced stage, the differences between the various types of disease are less noticeable as numerous parts and functions of the body are affected.

Muscle weakness

The limbs become progressively weaker and the muscles in your limbs begin to shrink. As a result, you'll find it increasingly difficult to move your affected limbs.

Muscle spasms

The twitching in your muscles will get worse, and it's likely that you'll experience muscle spasms or twinges. Certain muscles in your limbs may become unusually stiff. This type of muscle stiffness is known as spasticity.

Pain

The combination of muscle spasms and stiffness can lead to episodes of pain in your muscles and joints.

Difficulties swallowing

If you have not previously had difficulties swallowing, it's likely that you will have problems as the condition progresses, whatever type of motor neurone disease you have.

Difficulty communicating

Many people with motor neurone disease eventually find it increasingly difficult to control the muscles of their throat and mouth, making it hard to talk.

Excessive drooling

Your body may have problems controlling the amount of saliva it produces, which can cause excessive or constant drooling of watery saliva.

Excessive yawning

Some people with motor neurone disease have episodes of uncontrollable, excessive yawning, even when they're not tired. This can sometimes cause jaw pain.

Emotional changes

Motor neurone disease doesn't usually affect a person’s intelligence, but it can lead to changes in their personality and emotional state.

One of the most common signs is when a person has episodes of uncontrollable crying or laughter. Doctors may call this emotional lability.

There's often no connection between these episodes and a person’s emotional state or immediate environment. For example, someone with emotional lability may break into uncontrollable laughter when watching a news report about a serious incident, such as an air crash.

Changes to mental abilities

Occasionally, people with motor neurone disease may have difficulties with memory, learning, language and concentration. This is known as cognitive change. Some of these changes may be quite subtle, making it difficult to tell them apart from the normal ageing process.

Breathing difficulties

As the nerves and muscles that help control the lungs become progressively more damaged, your breathing will become increasingly difficult.

This usually starts as a feeling of being very short of breath after doing everyday tasks, such as walking up the stairs. Over time, you may become very short of breath even when you're resting.

This shortness of breath may be particularly troublesome at night. Some people find it difficult to breathe when they're lying down. Others wake up suddenly in the night due to breathlessness.

As motor neurone disease progresses, you're likely to need mechanical assistance with your breathing. For example, you may need to use an oxygen mask.

Secondary symptoms

Some people with motor neurone disease have additional symptoms that aren't directly caused by the condition but are related to the stress and anxiety of living with motor neurone disease.

These secondary symptoms include:

• depression
• insomnia
• anxiety

End stage symptoms

As motor neurone disease progresses to its final phase, you will probably experience:

• total body paralysis – being unable to move any parts of the body
• significant breathing difficulties

Eventually, mechanical assistance, such as using an oxygen mask, won't be enough to compensate for the loss of normal lung function.

At this stage, most people with motor neurone disease become increasingly drowsy before falling into a deep sleep. They usually die peacefully in their sleep.

Motor neurone disease occurs when motor neurones progressively lose their function.

Motor neurones are specialised nerve cells that send signals from the brain to the muscles and bones, enabling you to move them. They also help regulate many of the body’s automatic processes, such as breathing and swallowing.

In most cases, a person with motor neurone disease will not have a family history of the condition. This is known as sporadic motor neurone disease. Researchers believe that the cause is a combination of genetic, environmental and lifestyle factors that build up throughout life.

However, 10% of people with motor neurone disease have a close family relative who also has the condition. This is called familial motor neurone disease. The cause is a problem with their genes (see below).

Possible causes of motor neurone disease

It's still unclear exactly why the motor neurones begin to lose function. Most experts believe that the loss of function is caused by a combination of interrelated factors, some of which are outlined below.

Disrupted chemical communications

Nerve cells use special "messenger chemicals", called neurotransmitters, to transmit information from one cell to another. One of the neurotransmitters is called glutamate.

There's evidence that people with motor neurone disease may have too much glutamate.

Excess glutamate may disrupt the chemical communication that's needed to maintain normal nerve function.

Transport disruption

All cells contain transport systems, which move nutrients and other chemicals into the cell while moving waste products out of the cell.

Research suggests that the transport systems in motor neurones become disrupted very early in the initial stages of motor neurone disease. This may contribute to the loss of normal nerve function.

Aggregates

Aggregates are abnormal clumps of protein that develop inside motor neurones. They have been found in most cases of motor neurone disease. The clumps may disrupt the normal working of the motor neurones.

Toxic waste

Toxic waste can build up in cells over time as a natural by-product of normal cell activity, just as using a cooker repeatedly can cause grease to build up inside it.

The body gets rid of the toxic waste by producing substances known as antioxidants, which destroy the waste.

Research suggests that in motor neurone disease, the motor neurones don't produce enough antioxidants.

Mitochondria

Mitochondria are the "batteries" of cells. They provide the energy that a cell needs to carry out its normal function. Research has shown that the mitochondria in the motor neurones of people with motor neurone disease appear to be abnormal.

Lack of nutrients

Like all living tissue, motor neurones need a regular supply of nutrients. Motor neurones receive nutrients from a group of proteins known as neurotrophic factors. There's evidence that, in motor neurone disease, neurotrophic factors are not produced in the correct way. This may make the motor neurones more vulnerable to damage and affect their function.

Glia cells

Glia cells surround and support nerve cells, such as motor neurones, and help provide them with nutrients. Glia cells also help relay information from one nerve cell to another.

Some cases of motor neurone disease may be caused by problems with the glia cells, which mean that the motor neurones no longer receive the support and nutrition that they require to function normally.

Familial motor neurone disease

The fact that motor neurone disease can run in families suggests that genetic mutations inherited from parents may play a role in the condition.

A genetic mutation is when the instructions carried in all living cells become scrambled in some way. This means that one or more processes of the body don't work properly. (Read more about genetics).

So far, three genetic mutations have been identified. These have been found in genes called SOD1, TDP-43 and FUS.

If your father, mother, sister or brother developed familiar motor neurone disease, you have a 50% chance of developing it yourself.

Genetic testing is available to determine whether you have one of the mutated genes associated with familial motor neurone disease. Your GP can give you more information about this.

Diagnosing motor neurone disease can be difficult when the condition is in its initial stages.

This is because many of the early symptoms can be caused by other more common health conditions, such as:

• Multiple sclerosis – the ability of nerves to transmit information becomes disrupted.
• A trapped nerve – "wear and tear" of the bones that make up the spine can sometimes result in nerves becoming trapped and compressed under a section of the spine.
• A brain tumour – an abnormal growth of cells develops inside the brain.
• Peripheral neuropathy – part of the nervous system becomes damaged by another health condition, most commonly type 2 diabetes.
• Peripheral arterial disease – the arteries in the legs become clogged up with fatty deposits that restrict blood supply to the leg muscles.

Initial testing

To rule out other possible causes of your symptoms, you may be referred for a range of tests, such as:

• Blood tests and urine tests – these can be used for several reasons, such as checking for infection, assessing chemical composition inside your body, and seeing how well certain organs, such as your liver, are working.
• MRI scan – this provides a detailed image of the inside of your brain and nervous system.
• Electromyography (EMG) – this measures the electrical activity in your muscles.
• Nerve conduction test – this is similar to an EMG, but measures how quickly your nerves can conduct an electrical signal.
• Transcranial magnetic stimulation – this specially designed magnetic coil measures the electrical activity in your brain.

Confirming the diagnosis

Confirming a diagnosis of motor neurone disease can be time consuming, often taking more than a year.

This is because the doctor in charge of your care, most likely a neurologist (an expert in treating conditions that affect the nervous system), will want to be certain that your symptoms aren't due to another treatable or possibly curable condition.

The neurologist may also want to wait a few months to see how your symptoms progress before making a definitive diagnosis.

A confident diagnosis of motor neurone disease can only be made if:

• extensive testing has found no other possible cause for your symptoms
• you have the characteristic symptoms of motor neurone disease in three or more parts of your body (such as your arms, legs and mouth)

Examples of characteristic symptoms of motor neurone disease include:

• muscle weakness
• shrinking muscles
• twitching
• changes in normal muscle reflexes

Receiving the diagnosis

Being told that you have motor neurone disease can be emotionally devastating and the news can be difficult to take in. Many people who are diagnosed with the condition go through the classic stages of the grieving process, which are:

• Denial – you may initially disbelieve the diagnosis and think there's nothing wrong with you.
• Anger – you may feel angry towards friends, family or medical staff.
• Bargaining – sometimes, people with terminal conditions try to "bargain" with their doctors, asking for any sort of treatment that can prolong their life.
• Depression – you may lose all interest in life and feel that your situation is hopeless.
• Acceptance – you come to terms with the diagnosis, the feelings of depression pass, and you begin to plan for the rest of your life.

If you've been diagnosed with motor neurone disease, talking to a counsellor or psychiatrist may help combat feelings of depression and anxiety.

Taking antidepressants or medicines to reduce anxiety may also help as you move through the stages of the grieving process. Your care team can advise you about this.

You may also find it useful to contact the Motor Neurone Disease Association, which is the leading UK charity for people affected by the condition.

The Motor Neurone Disease Association can give you practical advice, support and information about living with motor neurone disease, and how to cope with the emotional impact of being diagnosed.

Your care team

If you're diagnosed with motor neurone disease, you'll be introduced to a team of health professionals who will be involved in your care. This team is often called a multidisciplinary team, because it contains experts from many different healthcare disciplines.

Advanced directive

Many people with motor neurone disease draw up an advanced directive. This is where you make your treatment preferences known in advance, in case you can't communicate your decisions later because you're too ill.

Issues that can be covered by an advanced directive include:

• whether you want to be treated at home, in a hospice or in a hospital once you reach the final stages of motor neurone disease
• what type of medications you'd be willing to take in certain circumstances
• whether you would be willing to use a feeding tube if you were no longer able to swallow food and liquid
• whether you're willing to donate any of your organs once you die (the brain and spine of people with motor neurone disease are particularly important for ongoing research)
• if you have respiratory failure (loss of lung function), whether you'd be willing to be resuscitated by artificial means, such as having a breathing tube inserted into your neck

Your care team can provide more advice about making an advanced directive.

Riluzole

Riluzole is the only medication that's available to treat motor neurone disease directly. Riluzole reduces the amount of glutamate in the body, which is thought to slow down the progressive damage to the motor neurone cells.

On average, riluzole can extend survival rates by three months, though this can vary from person to person.

Riluzole also has the benefit of extending the time that people with motor neurone disease have before they need artificial aids for loss of body functions, such as wheelchairs, feeding tubes and a face mask to help with breathing.

Side effects of riluzole include:

• nausea
• vomiting
• tiredness
• rapid heartbeat
• drowsiness
• headaches
• dizziness

Occasionally, riluzole has been known to damage the liver. Therefore, you'll need to have regular blood tests while taking riluzole to check that your liver is working properly. If you have had liver disease, riluzole may not be suitable for you.

Treating symptoms

A range of treatments can relieve many of the symptoms of motor neurone disease and improve your quality of life.

Muscle cramps

Muscle cramps can be treated with two different medications:

• phenytoin
• carbamazepine

These medicines were originally designed to treat epilepsy and were called anti-epileptic drugs or AEDs, but they have also proved useful in preventing cramping.

Muscle cramps can also be treated with physiotherapy.

Muscle stiffness

Muscle stiffness, also known as spasticity, can be treated using medication to relax the muscles (muscle relaxants).

If muscle relaxants aren't effective, an injection of botulinum toxin may be given. Botulinum toxin works by blocking the signals from the brain to the affected muscles. The effects of the injection normally last for up to three months.

Another possible treatment for muscle stiffness is intrathecal baclofen therapy. This involves surgically implanting a small pump on the outside of the body, which is connected to the spinal cord. The pump delivers regular doses of a medicine called baclofen into the nervous system.

Baclofen blocks some of the nerve signals that cause muscle stiffness. It can also help control the symptoms of excessive yawning.

Excessive drooling

The symptoms of excessive drooling can be treated with a number of medications. One widely used medication is hyoscine hydrobromide. It was originally designed to treat motion sickness, but has since proved useful in controlling symptoms of drooling.

Side effects of hyoscine hydrobromide include:

• drowsiness
• dizziness
• blurred vision

If you have any of these side effects, do not drive or operate complex or heavy machinery.

Glycopyrrolate is an alternative medicine that can be used to control drooling. It's usually given as an injection. Side effects of glycopyrrolate include:

• difficulty urinating
• rapid or irregular heartbeat
• blurred vision

If your drooling fails to respond to hyoscine hydrobromide or glycopyrrolate, a medication called atropine can be used.

Atropine works by blocking the normal functions of the saliva glands. It can be given as a tablet or injection.

Side effects of atropine include:

• dry mouth
• dry skin
• difficulties passing urine
• constipation
• changes in heartbeat (the heart can beat slower or faster than usual)

Communication difficulties

Not everyone with motor neurone disease will have speech problems, but there's a lot of help for people who do. A speech and language therapist can teach you several techniques to make your voice as clear as possible.

As motor neurone disease progresses, you may need some sort of assistive technology to communicate. A range of communication aids is available. Your therapist can advise you about the most effective communication aids for you.

Swallowing difficulties

As motor neurone disease progresses, swallowing problems (dysphagia) will become so severe that you won't be able to eat and drink normally.

One widely used treatment for dysphagia is a feeding tube known as a percutaneous endoscopic gastrostomy (PEG) tube. A PEG tube is surgically implanted into your stomach through a small incision on the surface of the stomach.

PEG tubes are designed for long-term use and last for up to six months before they need replacing.

Pain relief

If you have pain due to motor neurone disease, the type of painkiller recommended to control symptoms will depend on how severe your pain is.

Mild to moderate pain can often be controlled using non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen. More severe pain can be treated using an opiate-based painkiller, such as morphine.

In some cases, a type of medication called gabapentin is used.

Originally, gabapentin was designed to treat epilepsy, but it's also useful in treating pain.

Side effects of gabapentin include:

• drowsiness
• dizziness
• tiredness
• loss of co-ordination

Breathing difficulties

As motor neurone disease progresses, the muscles that help breathing will become weaker, and breathing will become increasingly difficult.

Breathing difficulties usually develop gradually, but they can also occur suddenly. Sometimes, they may even be the first sign of motor neurone disease.

It's important to discuss breathing problems with your GP before they occur. Your GP should be able to refer you to a respiratory specialist or a palliative care specialist, as appropriate.

Some people with motor neurone disease use mechanical ventilation to support their breathing. Several systems provide ventilation support. These are known as non-invasive ventilation (NIV). In all cases of mechanical ventilation, air is sucked in, filtered and pumped into the lungs through a face mask or a nasal tube.

NIV may not be suitable for everyone with motor neurone disease. Your respiratory or palliative care specialist can discuss the options available to you.

Deciding what treatment you want to use in the event of respiratory failure is an important part of drawing up a treatment plan and making an advanced directive (see above). This can be a very difficult and upsetting decision, and you may want to discuss it with your loved ones.

Your care team can give you information and advice, but the final decision will be yours.