What is motor neurone disease?
Motor neurone disease is the name for a rare condition where parts of the nervous system become damaged. This causes progressive weakness, usually with muscle wasting.
Motor neurone disease occurs when specialist nerve cells in the brain and spinal cord called motor neurones stop working properly. Motor neurones control important muscle activity, such as:
As the condition progresses, people with motor neurone disease will find these activities increasingly difficult – and eventually impossible – to do.
Exactly what causes motor neurones to stop working properly is unclear, but there is not currently thought to be a link with factors such as race, diet and lifestyle.
In about 5% of cases there is a family history of either motor neurone disease or a related condition called frontotemporal dementia. In most of these cases faulty genes have been identified as contributing to the condition.
There is no single test to diagnose motor neurone disease and diagnosis is based mainly on the opinion of a neurologist. Sometimes specialised tests are needed to rule out other possible conditions.
Progression of symptoms
The symptoms of motor neurone disease begin gradually over weeks and months, usually only on one side of the body initially, and get progressively worse. Common early symptoms are:
- a weakened grip, which can cause difficulty picking up or holding objects
- weakness at the shoulder that makes lifting the arm difficult
- a "foot drop" caused by weak ankle muscles
- dragging of the leg
- slurred speech (dysarthria)
The condition is not usually painful.
As damage progresses, symptoms spread to other parts of the body and the condition becomes more debilitating.
Eventually, a person with motor neurone disease may be unable to move. They may also find communicating, swallowing and breathing very difficult.
In 10-15% of cases, motor neurone disease is associated with a type of dementia that can affect things such as personality and behaviour. This is called frontotemporal dementia.
Read more about symptoms of motor neurone disease.
Treating motor neurone disease
There's currently no cure for motor neurone disease. Treatment therefore aims to:
- make the person feel comfortable and have the best quality of life possible
- compensate for the progressive loss of bodily functions such as mobility, communication, swallowing and breathing
For example, a breathing mask can help reduce shortness of breath, and the insertion of a small feeding tube (called a gastrostomy) helps maintain nutrition and overall comfort. Medication is used to help control oral secretions if necessary.
A medication called riluzole has shown a very small improvement in patients' overall survival, but it is not a cure and does not stop the progression of the disease.
Read more about treating motor neurone disease.
Motor neurone disease is a severely life-shortening condition for most people. Life expectancy for about half of those with the condition is three to four years from the start of symptoms. However, some people may live for up to 10 years, and others even longer.
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 strong community and specialist support, many people lead a relatively independent lifestyle and enjoy a quality of life they may not have imagined was possible at the time of their diagnosis.
In most cases, motor neurone disease is fatal because of the eventual involvement of the breathing muscles, which typically makes someone with the condition gradually more drowsy and more susceptible to chest infections.
The end of life in someone with motor neurone disease is not usually distressing and is most often in their own home. In a few cases, a person with motor neurone disease may die suddenly but painlessly during their sleep.
Motor neurone disease symptoms
The symptoms of motor neurone disease can be varied to begin with before getting progressively more widespread.
The symptoms usually follow a pattern that falls into three stages:
- the initial stage
- the advanced stage
- the end stage
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.
In about two-thirds of people with motor neurone disease, the first symptoms occur in the arm or leg. This is sometimes called limb-onset disease. These symptoms include:
- a weakened grip, which can cause difficulties picking up or holding objects
- weakness at the shoulder, making lifting the arm above the head difficult
- tripping up over a foot because of weakness at the ankle or hip
These symptoms are usually painless and may be accompanied by widespread twitching of the muscles (fasciculations) or muscle cramps.
In the other one-third of cases, problems initially affect the muscles used for speech and swallowing. Increasingly slurred speech (dysarthria) is usually the first sign of this type of motor neurone disease.
As the condition progresses, it may become increasingly difficult to swallow. The medical term for swallowing difficulties is dysphagia.
In very rare cases, motor neurone disease starts by affecting the lungs. This is called respiratory-onset disease. In some cases 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 the brain 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.
As motor neurone disease progresses to an advanced stage, the differences between the various types of disease are less noticeable as more parts and functions of the body are affected.
The limbs become progressively weaker and the muscles in your limbs begin to waste away. As a result, you'll find it increasingly difficult to move your affected limbs.
Certain muscles in your limbs may become unusually stiff. This type of muscle stiffness is known as spasticity.
Muscle wasting and stiffness can cause joint aches and pains.
Difficulties speaking and swallowing
About two-thirds of people with motor neurone disease eventually find the ability to speak and swallow increasingly difficult as the disease progresses. However, this is rarely fatal.
Reduced swallowing can cause excessive or constant drooling of watery saliva. Sometimes, thicker saliva may be harder to clear from the chest or throat because of weakened cough muscles.
Some people with motor neurone disease have episodes of uncontrollable, excessive yawning, even when they're not tired. This can sometimes cause jaw pain.
Motor neurone disease doesn't usually affect a person's intelligence, but it can lead to changes in their ability to control their emotions.
One of the most common signs is when a person has episodes of sudden uncontrollable crying or, more rarely, laughter. Doctors may call this emotional lability.
Changes to mental abilities
Occasionally, people with motor neurone disease may have difficulties with planning, language and concentration. This is known as cognitive change and overlaps with a condition called frontotemporal dementia.
Typically the changes are quite subtle, making it difficult to tell them apart from the normal ageing process, and do not usually affect a person's capacity to make their own decisions.
About 10% of people with motor neurone disease develop more profound frontotemporal dementia, typically soon after their first muscle symptoms.
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 may wake up suddenly in the night because of breathlessness.
As motor neurone disease progresses, a non-invasive breathing mask may be recommended at night to improve sleep quality and help reduce drowsiness during the day.
As motor neurone disease progresses to its final phase, a person with the condition will probably experience:
- increasing body paralysis, meaning they need help with most normal daily activities
- significant shortness of breath
Eventually, non-invasive breathing assistance 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 causes
Motor neurone disease occurs when motor neurones progressively lose their function. It is not clear why this happens.
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 probably a combination of genetic and environmental factors that build up throughout life.
However, about 5% of people with motor neurone disease have a close family relative who also has the condition or the related condition frontotemporal dementia. This is called familial motor neurone disease and is more closely linked to a problem with genes.
Possible causes of motor neurone disease
It's still unclear why the motor neurones begin to lose function. Most experts believe that the loss of function is caused by a combination of interrelated factors that affect your cells, some of which are outlined below.
Nerve cells use special "messenger chemicals" called neurotransmitters to transmit information from one cell to another. One of the neurotransmitters is called glutamate. There is evidence that the motor neurones in people with motor neurone disease may have become more sensitive to glutamate, resulting in damage to these cells. However, this is not linked to dietary intake of glutamate.
All cells contain transport systems that 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 in motor neurone disease. This may contribute to the loss of normal nerve function.
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 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. Research suggests that in motor neurone disease the motor neurones may be deficient in antioxidants, but there is no evidence that this is because of poor dietary intake.
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 are cells that surround and support 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 means 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 sometimes have a larger 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. See genetics for more information.
So far, four major genetic mutations have been identified in the 5% of patients with a family history of motor neurone disease or the related condition frontotemporal dementia.
The largest group (about one third) have an expanded area of a gene called C9orf72. Some people with this gene abnormality develop motor neurone disease, some develop frontotemporal dementia and some develop both. Other genes linked to familial motor neurone disease include SOD1, TDP-43 and FUS.
If your father, mother, sister or brother developed motor neurone disease and there is another family member with either motor neurone disease or frontotemporal dementia, you have a 50% chance of carrying the same gene. However, this does not mean you will definitely develop the disease.
If you have motor neurone disease and there is no wider family history, the overall risk to your own children is currently thought to be very similar to that of the general population.
Genetic testing is available to determine whether you have one of the mutated genes associated with familial motor neurone disease. Your doctor can give you more information about appropriate specialists who can help with the complex issue of when to perform genetic testing.
Diagnosing motor neurone disease
You should visit your doctor if you notice the symptoms of motor neurone disease.
After an initial examination, they may refer you to a neurologist (a specialist in disorders of the nervous system) for a further opinion and possibly tests.
However, diagnosing motor neurone disease can be difficult when the condition is in its initial stages because many of the early symptoms can be caused by other more common health conditions, such as:
- 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
- peripheral neuropathy – part of the nervous system becomes damaged by another health condition, most commonly type 2 diabetes
Motor neurone disease is called a clinical diagnosis. This means it is most often made by a specialist on the basis of the symptoms and a physical examination.
There is no single way to check for motor neurone disease, but various tests may be used to rule out other possible causes of your symptoms. These tests may include:
- blood tests – these can be used for several reasons, such as checking that certain organs, such as your thyroid, are working normally
- magnetic resonance imaging (MRI) scan – this provides a detailed image of the inside of your brain and spinal cord
- electromyography (EMG) – this measures the electrical activity in your muscles, which shows how well your motor neurones are working
- nerve conduction test – this is similar to an EMG, but measures how quickly your nerves can conduct an electrical signal
- lumbar puncture – a sample of spinal fluid is removed for testing to exclude an inflammatory nerve condition
- muscle biopsy – in rare cases, a small sample of muscle is removed for testing to help determine if the problem lies in the muscles or nerves
Confirming the diagnosis
Sometimes the diagnosis of motor neurone disease is clear without the need for any further tests. However, confirming a diagnosis of motor neurone disease can sometimes be time-consuming, occasionally taking more than a year.
There are many reasons why there may be delays. It may be that the initial symptoms are not thought to be serious, or they are not recognised as being related to the nervous system and a neurologist is not initially consulted.
Sometimes even a neurologist needs time to be certain that your symptoms aren't caused by another condition, especially if it is a treatable one.
A diagnosis of motor neurone disease can only be made if the symptoms are getting worse (progressive).
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 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 or that your doctor has missed another diagnosis
- 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
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. They also run a network of specialist hospital clinics across the UK, where a neurologist who is an expert in motor neurone disease can provide advice.
Treating motor neurone disease
There is no cure for motor neurone disease, but treatment can help relieve symptoms and slow the progression of the disease.
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.
Many people with motor neurone disease draw up an advance decision. 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 advance decision 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 consider 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) in the late stages of motor neurone disease, whether you wish to be resuscitated by artificial means, such as having a breathing tube inserted into your throat
Your care team can provide more advice about making an advance decision.
[Riluzole] is the only medication that has demonstrated a survival benefit for people with motor neurone disease. Riluzole is thought to slow down the progressive damage to the motor neurone cells by reducing their sensitivity to the nerve transmitter glutamate.
In medical research, riluzole extended survival by two to three months on average, though this varied from person to person and the disease continued to progress even with riluzole treatment.
Side effects of riluzole are usually mild and commonly include nausea, tiredness and a rapid heartbeat.
Very rarely, riluzole has been known to damage the liver. People prescribed riluzole therefore need to have monthly blood tests for the first few months to check their liver is working properly. If you have had liver disease, riluzole may not be suitable for you.
A range of treatments can relieve many of the symptoms of motor neurone disease and improve your quality of life.
Muscle cramps can be treated with a medication called quinine or with physiotherapy.
However, there are some uncertainties surrounding the use of quinine for muscle cramps. This is because there is a risk of side effects such as:
- hearing problems
- tinnitus – the perception of noise in one ear, both ears or the head
- vertigo – a sensation that you, or the environment around you, is moving
- vision problems
Therefore, quinine will usually only be used if the potential benefits are thought to outweigh the risks.
Muscle stiffness, also known as spasticity, can be treated using medication such as [baclofen] to relax the muscles. Side effects may include increased weakness or tiredness.
Drooling can be treated with a number of medications. One widely used medication is a hyoscine hydrobromide skin patch. It was originally designed to treat motion sickness, but has since proved useful in controlling symptoms of drooling.
Side effects of hyoscine hydrobromide are uncommon, but can include:
- blurred vision
If you have any of these side effects, do not drive or operate complex or heavy machinery.
Amitriptyline, glycopyrrolate, atropine eye drops or botulinum toxin injections are alternative medicines that can also be used to control drooling.
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.
As motor neurone disease progresses, swallowing problems (dysphagia) may become so severe that you won't be able to eat and drink normally.
One widely used treatment for dysphagia is a thin feeding tube known as a percutaneous endoscopic gastrostomy (PEG) tube. A PEG tube is surgically implanted into your stomach through a small cut on the surface of the stomach. The feeding tube doesn't usually restrict your daily activities and you can continue to bathe and swim normally if you wish.
If you have pain caused by the condition (usually joint pain caused my muscle weakness), the type of painkiller recommended to control the 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 is very rare, but it can be treated using an opiate-based painkiller such as morphine.
In some cases, a type of medication called gabapentin is used. Gabapentin was originally designed to treat epilepsy, but it's also useful for treating pain. Typical side effects of gabapentin include drowsiness.
As motor neurone disease progresses, the muscles that help breathing will become weaker and breathing will become increasingly shallow, with a weaker cough.
Breathing difficulties usually develop gradually, but very rarely they may be the first sign of motor neurone disease.
It's important to discuss breathing problems with your doctor before they occur. Your doctor 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 advance decision. 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.
Some people with motor neurone disease find complementary therapy helpful. This involves combining conventional treatments with non-medical treatments, such as acupuncture.
Complementary therapies do not slow down the progression of motor neurone disease, but may help reduce stress and make your daily life more comfortable.
Before considering complementary therapy, you should seek advice from your treatment team and ensure that any practitioners you contact are appropriately registered, qualified and experienced.