الاثنين، 20 يناير 2014

Motor neurone disease (MND) causes a progressive weakness of many of the muscles in the body. There are various types of MND. This leaflet is mainly about amyotrophic lateral sclerosis, which is the most common type of MND. Although there is no cure for MND, treatments can help to ease symptoms and disability.
Nerves (neurones) are like wires that carry tiny electrical impulses (messages) between the brain, spinal cord and the rest of the body.
  • Motor nerves carry messages from the brain and spinal cord to muscles, and make the muscles contract.
  • Sensory nerves carry messages of touch, temperature, hearing, smell, taste and other sensations from various parts of the body to the brain.
In motor neurone disease (MND), motor nerves become damaged and eventually stop working. Therefore, the muscles that the damaged nerves supply gradually lose their strength. There are various subtypes of MND. In each type, symptoms tend to start in different ways. However, as the disease progresses, the symptoms of each type of MND tend to overlap. This means that symptoms in the later stages of each type of MND become similar. The main types of MND are:
  • Amyotrophic lateral sclerosis (ALS). This is the classical MND and the most common type. About 8 in 10 people with MND have this type. Symptoms tend to start in the hands and feet. The muscles tend to become stiff as well as weak at first.
  • Progressive bulbar palsy (PBP). About 2 in 10 people with MND have this type. The muscles first affected are those used for talking, chewing and swallowing (the bulbar muscles).
  • Progressive muscular atrophy (PMA). This is an uncommon form of MND. The small muscles of the hands and feet are usually first affected, but the muscles are not stiff.
  • Primary lateral sclerosis (PLS). This is a rare type of MND. It mainly causes weakness in the leg muscles. Some people with this type may also develop clumsiness in the hands or develop speech problems.
The rest of this leaflet is just about the ALS type of MND (ALS-MND).
ALS-MND is uncommon in the UK. Around 2 people in 100,000 develop ALS-MND each year. There are about 5,000 people in the UK with ALS-MND.
ALS-MND can affect anyone. ALS-MND is rare under the age of 40 years. It usually develops between the ages of 50 and 70 years. It is twice as common in men as in women.

For the vast majority of cases, it is not inherited and it does not run in families. Around 1 case in 20 is due to an inherited form of MND.
The cause is not known. It is thought that certain chemicals or structures that only occur in motor nerves are damaged in some way. The reason why the nerves become damaged is not clear. (It is also not clear why sensory nerves, which have a similar structure, are not affected.) There may be one or more environmental factors that may trigger the damage in someone who is prone to the disease. Research continues in order to find the underlying cause of the damage to the nerves.
This disease affects different people in different ways.

The main feature of ALS-MND is muscle weakness which is mild at first, but gradually becomes worse. The first symptoms commonly develop in the hands and arms, or feet and legs. Less commonly, the first symptoms are in the bulbar muscles (muscles around the face and throat):
  • Hand and arm symptoms. At first you may notice that your grip is less strong. You may drop things, and find it difficult to open bottle tops, turn keys, etc. You may also notice that the muscles in your hands (especially at the base of your thumbs) become flatter with time.
  • Feet and leg symptoms. At first you may start to drag one leg or tend to trip easily. You may find it more difficult to climb stairs or rise out of low chairs. You may find you are much more tired after walking.
  • Bulbar muscle symptoms. You may not be able to shout or sing. Your speech may become slurred. There may be a change in the quality of your voice. You may experience some difficulties with swallowing as the muscles which co-ordinate swallowing become affected.
  • Other symptoms that may occur include: muscle cramps, tiredness, twitching of weakened muscles (fasciculation), and jerking of an arm or leg whilst you rest.
Symptoms may affect just one arm or leg at first. They then gradually become worse, and spread to involve other limbs. Eventually, many muscles in the body become affected. Some muscle groups may be more badly affected than others. Muscles gradually become weaker and wasted. The problems that develop may eventually include the following:
  • Mobility (walking) typically becomes worse.
  • Doing tasks with your arms and hands becomes increasingly difficult.
  • Eating and swallowing become difficult when the tongue and the muscles around the mouth and throat become weak.
  • Sneezing and coughing become weak.
  • You may become breathless on minimal exertion when the chest muscles become affected.
  • Intellect does not usually change, as the thinking part or the brain is not usually affected. However, a rare subtype of MND (about 3 in 100 cases) is associated with early dementia.
  • Sensory parts of the nervous system are not affected, so you can feel, see, smell, taste and hear as before.
  • Bladder and bowel functions usually remain normal, so incontinence is not usually a feature. However, poor mobility may cause continence problems in the later stages of the illness.
  • Emotional feelings and sexual desire are not directly changed by ALS-MND. However, some people with ALS-MND suddenly cry or laugh in inappropriate moments. (This is not a sign of mental illness, but a feature of ALS-MND and cannot be helped, although may be embarrassing when it occurs.) Also, depression and anxiety are common.
Unfortunately, there is no test that confirms ALS-MND. People with suspected ALS-MND are normally referred to a specialist (neurologist) for assessment. At first it may be difficult for a specialist to be sure that you have ALS-MND when early minor symptoms first develop. However, the diagnosis usually becomes clear as the typical symptoms and signs of the disease gradually become worse.

Tests are often done to exclude other causes of your symptoms. The following tests may be advised:
  • Electromyography (EMG). In this test, very small needles are used to record the nerve impulses occurring within your muscles (usually in your arms, legs and throat).
  • Nerve conduction studies. An electrical impulse is applied through a small pad on the skin to measure the speed at which your nerves carry electrical signals.
  • Transcranial magnetic stimulation (TMS). This test measures the activity of the nerves which run from your brain to your spinal cord.
  • Other tests, such as an MRI brain scan, may be done to rule out other causes of your symptoms if there is doubt about the diagnosis.
Although there is no cure for ALS-MND, treatments can help both to slow the disease and also to improve any symptoms you may have.

Riluzole

Riluzole is a medicine which has been shown in clinical trials to have a beneficial effect on the survival of people with ALS-MND. It can slow down the progress of the disease by a few months. Riluzole helps to inhibit the amount of glutamate released in nerve impulse transmissions. Glutamate is a chemical which relays signals between a nerve and another cell in the central nervous system. Glutamate in excess has been shown to cause brain and spinal cord nerve damage. This has some protective effect on the nerves.

There is currently no good robust evidence showing that taking antioxidants is of any benefit.

Respiratory care

This has been a great advance in treating people with ALS-MND over recent years. In this treatment, you are given a mask ventilator system to wear overnight while you are sleeping. The machines are small and portable and you can choose from a variety of different masks to suit you. People using this have been shown not only to have longer survival but also an improvement in the quality of their life.

Treatments to help ease symptoms

Treatments are available for many of the symptoms that you may develop with ALS-MND. These may include cramps, difficulty swallowing saliva and food, urinary symptoms, and depression.

It can be fairly common for people with ALS-MND to have feeding problems. These may either be due to difficulty swallowing or to difficulty in actually feeding yourself due to the weakness in your arms and hands. Some people find that having thickened fluid and sitting very upright when eating is beneficial.

If you are losing weight as a result of having feeding difficulties then you may benefit from having a gastrostomy inserted. This is a small feeding tube that is placed through the wall of the abdomen directly into your stomach. Your doctor will discuss this in more detail with you if you are suitable for one.

Most people with ALS-MND are cared for by a professional team which includes neurologists, specialist nurses, physiotherapists, speech and language therapists, occupational therapists, dietitians, and counsellors. Each problem that arises is assessed and dealt with as far as possible by the relevant members of the team.
The rate at which the disease progresses varies from person to person. Muscles weakened by ALS-MND do not recover. However, weeks or months may go by where the disease does not seem to progress. Eventually, severe disability develops. As the disease becomes severe, people with ALS-MND are unable to walk, talk or eat, and need a lot of care. The outlook for people with ALS-MND is variable. About 7 in 10 people with ALS-MND die within 3-5 years of the onset of symptoms. About 2 in 10 survive five years, and about 1 in 10 survives 10 years or more.

There are currently many research studies looking at different potential treatments for ALS-MND. It is hoped that new treatments will be introduced in the future.
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