Motor neurone disease (MND)
Motor neurone disease (MND) is a rare condition that progressively damages parts of the nervous system. This leads to muscle weakness, often with visible wasting.
Amyotrophic lateral sclerosis (ALS) is the most common form of MND.
MND happens when specialist nerve cells in the brain and spinal cord, called motor neurones, stop working properly and die prematurely. This is known as neurodegeneration.
Motor neurones control muscle activity like:
As MND progresses, it can become more difficult to do some or all of these activities.
Symptoms of motor neurone disease
The symptoms of MND start gradually over weeks and months. They tend to appear on one side of the body first and get progressively worse.
Non-urgent advice: Speak to your GP if:
- you have early symptoms of MND
Being referred to a specialist as early as possible can help you access the right support.
There are usually 3 stages of symptoms.
Sometimes the early symptoms are mistaken for similar conditions that also affect the nervous system.
In about two-thirds of people with MND, the first symptoms are in the arm or leg. This is sometimes called limb-onset disease. The symptoms include:
- a weakened grip, which can cause problems picking up or holding objects
- weakness at the shoulder, making lifting your arm above your head difficult
- tripping up over your foot because of weakness at your ankle or hip
These symptoms are usually painless. You might also experience widespread twitching of the muscles (fasciculations) or muscle cramps. You might also see wasting of the muscles with significant weight loss.
In 1 out of 4 cases, the first MND symptoms will affect the muscles used for speaking and swallowing.
These problems might initially affect the muscles used for speech and swallowing. Increasingly slurred speech (dysarthria) is usually the first sign of this type of MND. It might be misdiagnosed as a stroke.
As the condition progresses, it may become increasingly difficult to swallow (dysphagia). This might be misdiagnosed as a blockage in the throat.
In rare cases, MND starts by affecting the lungs, rather than affecting them at the end of the condition. This is called respiratory-onset disease.
In some cases the initial symptoms like breathing difficulties and shortness of breath are more obvious.
You might suffer from a lack of sleep and a headache in the morning. This might be because your body isn't getting rid of the carbon dioxide you normally breathe out.
As MND becomes more advanced, more parts and functions of the body are affected. This can make you more likely to experience infections, like chest infections, which can cause your condition to get worse quicker.
The limbs will become weaker. The muscles in the limbs may become thinner. As a result, the person will find it increasingly difficult to move the affected limbs.
The limbs may also become stiff. This is known as spasticity. Both muscle wasting and stiffness can also cause joint aches and pains.
Speaking and swallowing difficulties
Speaking and swallowing can become increasingly difficult as MND progresses.
Choking episodes can be distressing but they aren't usually the cause of death.
Reduced swallowing can cause excess saliva. This can cause drooling. Thicker saliva can sometimes be difficult to clear from the chest or throat. This is because the muscles that control coughing become weak.
Some people with MND have episodes of uncontrollable excessive yawning. This can happen even when they're not tired. It can sometimes cause jaw pain.
MND can cause changes in your ability to control your emotions. This is more likely when there's weakness in the muscles that control speech and swallowing.
One of the most common signs is when a person has episodes of sudden uncontrollable crying or, more rarely, laughter. This is sometimes called emotional lability or emotionality.
Changes to mental abilities
Sometimes, people with MND have significant difficulties with:
- behavioural changes.
This is where the condition is causing a type of dementia (usually frontotemporal dementia).
Up to 15% of people with MND develop more profound frontotemporal dementia. This usually happens soon after, or sometimes before, their first muscle-related symptoms. Someone with MND might not be aware that there are problems with their behaviour or personality.
Breathing might become less efficient as the nerves and muscles that help control the lungs become more damaged.
This might mean you feel short of breath after doing every day tasks like walking up the stairs. Over time, you might become even more out of breath when you're resting.
Shortness of breath can become a problem at night. Some people find it difficult to breathe when they're lying down. Others might wake in the night because they feel breathless.
As breathlessness increases, breathing support can help reduce this symptom. This is usually given by non-invasive ventilatory (NIV) support. It can be useful at night to improve your sleep quality. This can help reduce drowsiness during the day.
As MND progresses to its final phase, you might experience:
- increasing body paralysis, which means you'll need help with most daily activities
- significant shortness of breath
Eventually, non-invasive breathing assistance won't be enough to make up for the loss of normal lung function. At this stage, more medication can help to reduce symptoms of breathlessness and anxiety related to it. Most people with MND become increasingly drowsy before falling into a deep sleep, where they usually die peacefully.
Some people with MND have other symptoms that aren't directly caused by the condition, but are related to the stress of living with it. These might include depression, insomnia and anxiety.
Causes of motor neurone disease
MND occurs when specialist nerve cells (motor neurones) in the brain and spinal cord progressively fail. It's not clear why this happens.
One known cause of MND is an error in your genes with 20% of cases linked to genetic causes. Half of genetic cases will be in people who have a family history of MND. The other half of genetic cases will occur in those without a family history.
Having a family history of frontotemporal dementia can also increase the risk of inheriting MND.
The error in the gene affects the cells ability to perform normally and survive.
If you have a genetic form of MND, there's a chance that you could pass the risk of developing MND on to your child. The risk of them developing the condition can be affected by many factors like age.
Not everyone who has the genetic mutation will develop MND in their lifetime. Typically, the longer you live, the more likely you are to develop the condition.
If you have a parent with MND with no other family history of the disease, you're at a slight increased risk of MND of about 1.4%. The risk to the general population of MND is about 0.3%.
Other possible causes of motor neurone disease
It's unclear why the motor neurones begin to lose function. Most experts believe that it's a combination of factors that affect either the motor neurones or the cells that support them. There are some theories involving different cell processes including:
Aggregates and RNA processing
Aggregates are abnormal clumps of protein that develop inside motor neurones. They're found in nearly all cases of MND and may disrupt the normal working of the motor neurones. It can also be a marker that the cell is under stress.
The protein TDP-43 is most commonly found in these aggregates. This is a protein involved in the processing of the genetic instructions for the cell through a molecule known as RNA. Mutations in the gene (TARDBP) coding for this protein can be a cause of genetic cases of MND.
Cell transport disruption
All cells have transport systems that move nutrients and other chemicals into the cell and waste products out of the cell. Research suggests that the transport systems in motor neurones become disrupted. Over time, toxic waste can build up in cells as a natural by-product of normal cell activity and aging.
The body gets rid of the toxic waste by waste disposal systems that can be affected by ageing and the environment.
Glial cells surround and support motor neurones and provide them with nutrients.
When they don't work properly the motor neurones no longer receive the support and nutrition they need to function normally.
Their involvement in MND is still being researched.
Nerve cells use special "messenger chemicals" called neurotransmitters to pass information between cells. One of the neurotransmitters is called glutamate. It excites neurones and one theory is that too much activity through this causes damage to the neurones.
Riluzole, a drug used to treat MND reduces the level of neuronal activity by blocking the action of Glutamate.
Mitochondria are the "batteries" of cells. They provide the energy that a cell needs to carry out its normal function. Mitochondria in the motor neurones of people with MND might not function properly.
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
MND is usually diagnosed by a neurologist based on the symptoms and a physical examination.
There's no single test for MND. Various tests might be used to rule out other possible causes of the your symptoms. Tests might include:
- blood tests – these can be used for several reasons, like checking that organs are working, or to look for a marker of muscle damage (creatinine kinase)
- magnetic resonance imaging (MRI) scan – to give a detailed picture of your brain and spinal cord
- electromyography (EMG) – measures the electrical activity in your muscles, which shows how well your motor neurones are working and connecting to the muscles
- nerve conduction test – similar to an EMG but measures how quickly your nerves can conduct an electrical signal
- lumbar puncture – a sample of spinal fluid might be tested to exclude an inflammatory or nerve condition caused by an infection
- muscle biopsy – in rare cases, a small sample of muscle might be removed for testing to determine whether the problem lies in the muscles
Gene tests can be used to support the diagnosis in some individuals. They might provide an explanation of why they've developed the disorder. Your GP can give you more information about specialists who can help with genetic testing.
Confirming the diagnosis
There are many reasons why there may be delays in diagnosis. The initial symptoms might not appear to be serious. Or symptoms might not be recognised as being related to the nervous system so a neurologist isn't consulted at first.
Sometimes, the diagnosis of MND is clear without the need for further tests. Confirming a diagnosis can sometimes be time-consuming even for an experienced neurologist. They might need a period of observation to be sure, particularly in cases where the condition progresses slowly. MND can only be diagnosed if the symptoms are clearly getting worse (progressive).
Receiving the diagnosis
Being told you have MND can be devastating and the news can be difficult to take in at first.
After you're diagnosed you should be provided with contact details of an MND care specialist. These are healthcare professionals with specialist experience caring for people with MND. They'll be able to give you (and your family) extra support after the diagnosis and during your time with the illness.
Talking to a counsellor or a trained clinical psychologist might help with feelings of depression and anxiety.
It's not unusual to have thoughts of taking your own life, although very few people with MND go on to do this. You should discuss these thoughts with your doctor.
Taking antidepressants or medicines to reduce anxiety may help. Your care team will be able to tell you about this.
Treating motor neurone disease
Although there's no cure for MND, there are treatments available to help relieve the symptoms.
A team of healthcare professionals will work together to help care for you. This multidisciplinary team typically includes:
- a neurologist and an MND care specialist
- a specialist in breathing (respiratory specialist)
- physiotherapists to advise on mobility aids
- occupational therapists to assess the need for adaptations to living environments
- speech and language therapist to provide help with communication and swallowing
- dieticians to support nutrition
As the conditions advances, you might also need palliative care.
Riluzole is the only licensed medication in the UK that's shown a survival benefit for people with MND. Riluzole is thought to slow down the damage to the motor neurone cells by reducing their sensitivity to the nerve transmitter glutamate.
In medical research, riluzole extended survival by 2 to 3 months on average.
Side effects of riluzole are usually mild and can include nausea, tiredness and, less commonly, a rapid heartbeat.
Very rarely, riluzole has been known to cause liver damage. If you're prescribed riluzole you'll need to have blood tests for the first few months to check your liver is working properly. If you've had significant liver disease, riluzole may not be suitable for you.
There are treatments available that can help relieve many of the symptoms of MND and improve your quality of life.
Physiotherapy can help muscle cramps. In some cases, a medication called quinine can help treat muscle cramps too. They often improve later in the condition.
Quinine can cause side effects like:
- hearing and vision problems
- tinnitus – the perception of noise in one ear, both ears or inside the head
- vertigo – a sensation that you, or the environment around you, is moving
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 like baclofen. This helps to help relax the muscles. Side effects can include increased weakness or tiredness.
Medication is available to treat drooling of saliva. One option is a hyoscine hydrobromide skin patch.
Alternative medicines used to control drooling include:
- atropine eye drops applied to the tongue
- botulinum toxin injections into the glands that produce saliva
Not everyone with MND will have significant speech problems.
There are ways to help people who find it hard to communicate. A speech and language therapist can teach you techniques to make your voice as clear as possible.
As the disease progresses, you may need assistive technology to help you communicate. A range of communication aids is available. Your therapist will be able to tell you about the most effective communication aids for you.
Not everyone with MND will have significant swallowing problems (dysphagia). For those that do, it can prevent normal eating and drinking. This can lead to you feeling more tired. If food or fluid goes down the wrong way into the lungs it can cause chest infections (called aspiration).
One common treatment for dysphagia is a feeding tube known as a gastrostomy tube. The tube is surgically implanted into your stomach through a small cut on the surface of the stomach. It shouldn't restrict your daily activities. You can continue to bathe and swim if you wish.
Ideally you should have the tube inserted before you become too frail. This is so you can get the best out of it and to give yourself the best chance of recovering from the procedure.
If you have thick secretions (fluids) you can't cough up yourself, medicine like carbocisteine and acetylcysteine might help.
As MND progresses, the muscles that help you breathe will become weaker. Your breathing will become increasingly shallow, with a weaker cough.
Breathing difficulties usually develop gradually. They're sometimes the first sign of MND, although this is rare.
It's important to discuss breathing problems with your GP before they occur. Your GP or neurologist should be able to refer you to a respiratory (breathing) specialist or a palliative care specialist, depending on your needs.
You might benefit from non-invasive mechanical ventilation (NIV) to support your breathing. Room air (not oxygen) is sucked into a small box. It's filtered and then gently pumped into the lungs through a face mask or nasal tube each time you take a breath.
NIV may not be suitable for everyone with MND. Your healthcare team will be able to discuss the options available to you.
Advance decision making
Many people with MND draw up an advance decision (sometimes called an advanced directive). This is where you decide your treatment preferences 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 MND
- the type of medication you'd be willing to take in certain circumstances
- whether you'd be willing to consider a feeding tube if you were no longer able to swallow food and liquid
- if you have respiratory failure (loss of lung function), whether you wish to have artificial resuscitation, like having a permanent breathing tube inserted into your throat (known as a tracheostomy)
- whether you'd be willing to donate any of your organs after you die (the brain and spinal cord of people with MND are very important for ongoing research)
Your care team will be able to provide you with more information and advice about making an advance decision.
Research and drug trials
You might be given the opportunity to take part in research, including drug trials. Your MND care specialist and neurology consultant can provide further information on this.
Advice for carers
Caring for someone with MND can be both physically and emotionally demanding. It's likely you'll need a wide range of support.
For information and advice about all aspects of caring, visit Care Information Scotland
22 February 2023
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