Myositis

What is myositis?

Myositis is the name for a group of rare conditions that can cause muscles to become weak, tired and painful.

The word myositis simply means inflammation in muscles. If something is inflamed, it may be swollen.

Myositis can affect people of any age, including children.

The main muscles to be affected are around the shoulders, hips and thighs.

肌炎也可能导致身体的其他部位受到影响,例如皮肤,肺或心脏。

Sometimes myositis can affect the muscles that carry out tasks such as breathing and swallowing.

There are several types of myositis. The two most common types are polymyositis and dermatomyositis.

‘Poly’ means many. Polymyositis means that many muscles are affected by inflammation. This type doesn’t often affect other parts of the body much.

Dermatomyositis causes similar symptoms in muscles, but there is also a skin rash. ‘Derma’ means skin.

Polymyositis, dermatomyositis, as well as other types of myositis, are autoimmune conditions.

The immune system is the body’s natural self-defence system. When healthy, it protects us from infection, injury and illness.

However, in people who have autoimmune conditions, the immune system gets confused and mistakenly attacks the body’s own healthy tissues.

One feature of a healthy immune system is inflammation. For example, when we have a cut, the body sends fluid to the affected area so that white blood cells can fight off any infection.

If someone has an autoimmune condition the body can create inflammation when there is no infection to fight. The unnecessary inflammation can then cause problems.

Symptoms

The symptoms of myositis vary between different people.

They can include:

  • weak and tired muscles that can make everyday tasks such as climbing stairs, brushing hair, and getting in and out of cars difficult
  • pain in muscles
  • muscles feeling tender to touch
  • muscles can sometimes swell
  • generally feeling unwell
  • weight loss
  • night sweats.

The most common muscles to be affected are around the shoulders, hips and thighs.

The weakening and tiredness in the muscles can make people with myositis more likely to fall over.

使用皮肌炎,您可以有上述症状以及:

  • a red or pink rash on the upper eyelids, face and neck, and on the backs of the hands and fingers
  • swelling of the affected skin
  • puffiness and colouring around the eyes.

Some other medical conditions can appear similar to myositis. These include:

  • the side effects of some medications – for example,steroidsand drugs to lower your cholesterol levels, such as statins
  • effects of drinking too much alcohol over a long period
  • hormonal conditions – for example, under- or overactive thyroid glands
  • low vitamin D levels
  • abnormal calcium or magnesium levels
  • infections
  • other rare muscle conditions – for example, where muscles waste away.

其他类型的肌炎

Polymyositis and dermatomyositis are the two main types of myositis. Here are some of the others:

Inclusion body myositis (IBM)

Inclusion body myositis (IBM) causes weakness in muscles, usually near the ends of the arms or around the tops of the legs. This can make it difficult to grip objects, or can cause the knee to give way and lead to falls. This condition can also make swallowing difficult.

The effects can happen slowly over 10 to 15 years. It affects more men than women, and generally starts once people are over the age of 50.

The key difference in inclusion body myositis compared to other types of myositis is that as well as inflammation in the muscles, there is also a build-up of protein. These tiny clumps of protein can only be seen with special microscopes. They might not be seen clearly in the early stages of the condition. And so it can be difficult to tell the difference between polymyositis and inclusion body myositis.

Inclusion body myositis doesn’t respond to steroids ordisease modifying anti-rheumatic drugs (DMARDS), that are used to treat other types of myositis. It’s thought that this resistance to treatment is related to the clumps of protein in the muscle cells, which the body cannot break down.

If you’re diagnosed with polymyositis and steroids aren’t working, you may need further tests to look more closely for inclusion body myositis.

While there are no effective drugs for inclusion body myositis, the following can really help:

抗合成酶综合征

抗合成酶综合征is a condition where several parts of the body are affected by inflammation.

It can affect the muscles, and elsewhere, such as the lungs and skin. This lung condition can potentially be serious, which is why prompt medical treatment is important. Early symptoms can be a dry cough, which can occur before skin and muscle symptoms.

People with anti-synthetase syndrome might also have a condition calledRaynaud’s phenomenon。在这种情况下手指和脚趾改变有限公司lour when cold. They may turn white, then blue and feel very cold to touch. When they warm up again, the fingers and toes may go red and start to throb or swell.

有些人用这个条件我过去ncorrectly been told that they have polymyositis or dermatomyositis. It has some similar symptoms, but is now being classed as a separate condition.

Immune-mediated necrotising myopathy

最近发现了这种肌炎。它导致肌肉细胞在称为坏死的过程中迅速死亡。弱点通常非常严重,患有这种情况的人通常会难以行走和使用手臂。在极少数情况下,可以通过他汀类药物触发这种疾病。

Post-infectious reactive myositis

Infectious or post-infectious reactive myositis can occur during and after some viral infections. Even after the virus has gone, the immune system may cause inflammation in some parts of the body for a few months.

Symptoms are similar to those of polymyositis, such as muscle pain and weakness. Usually, the condition is mild and can settle without treatment.

In rare cases, some people who have HIV infection can develop long-term viral muscle infections.

Drug-induced myopathies

Drug-induced myopathies can sometimes appear like myositis. The most common drugs to cause this are statins used to lower people’s cholesterol levels. Usually, stopping this drug treatment leads to improvement in symptoms. Occasionally, the symptoms can last after the drug treatment has been stopped and people can develop myositis.

How will myositis affect me?

In most cases the pain and feelings of being unwell are eased with drugs. Even in severe cases most people with myositis eventually respond to treatment.

You may need to try more than one treatment before you find the right one for you.

Muscle strength can take longer to get back to normal. Once myositis is controlled with treatment, exercises can also help to improve muscle strength.

Although people can make a good recovery, some never regain their original muscle strength or function.

Complications

有时,药物治疗无法完全起作用,肌肉会保持弱。我们仍在研究为什么是这种情况。

Occasionally, myositis can affect breathing and swallowing. This may occur at the start of severe cases when the muscles used for these important tasks become weak.

On rare occasions, this condition may cause weakening of the heart.

If there is inflammation in the lungs this can cause scarring, which can affect how the lungs work.

Lung and heart conditions can cause long-term breathlessness. For this reason, you may be referred to a heart or chest specialist if there’s a risk of these problems developing.

Children with dermatomyositis may develop painful deposits of the mineral calcium in damaged muscles. These deposits, combined with loss of mobility, can occasionally result in permanently rigid joints, which are called contractures.

Polymyositis occasionally occurs in patients who have other autoimmune conditions such asrheumatoid arthritis,lupus或者scleroderma

On rare occasions, myositis can be associated with cancer. Most people with myositis don’t develop cancer, but your doctor might arrange tests such as a chest x-ray or an ultrasound scan of your abdomen and pelvis to be on the safe side.

Diagnosis

There is no single test that can show for certain if someone has myositis.

Your doctor will talk to you about your symptoms and examine you.

由于肌炎的症状与许多其他疾病相似,因此您可能会接受血液检查和其他检查。

Blood tests

Blood tests can look for:

  • signs of damaged muscles
  • inflammation levels within the body
  • the presence of autoantibodies, which are tiny proteins that can attack the body’s own healthy tissues and cells.

There is no autoantibody test that can prove for certain you have myositis, but there are tests that can be helpful in making a diagnosis.

One of these is the anti-nuclear antibody test (ANA). This is a test to see if your blood has antibodies that attack the central part of a cell called the nucleus.

Healthy people can also test positive so it’s only helpful alongside all the other information about your symptoms.

其他自身抗体测试包括ENA(可提取的核抗原)和抗JO-1测试。这些测试有时对肌炎患者呈阳性。

现在有很多不同的自身抗体which can be present in people with myositis. Tests for these can sometimes be useful for predicting your responses to treatment.

Even if these tests haven’t led to a diagnosis of myositis, they may have helped your doctor rule out other conditions. There are other tests to help confirm a myositis diagnosis.

Electromyography

You may have a test called electromyography (EMG). This involves a tiny needle electrode, being inserted into the muscle to record electrical messages from nerve endings that enable your muscles to move.

An unusual pattern of electrical activity in a number of different muscles can be due to myositis. The test isn’t very painful but may be uncomfortable.

Muscle biopsy

您的肌肉的一小部分可以取自您的大肌肉之一,例如在大腿或小腿的侧面,并在显微镜下检查以寻找炎症迹象。这称为活检。

You’ll be given a local anaesthetic to numb the area while the sample is taken, but there may be some discomfort for a few days afterwards.

有时,如果您的病情无法改善标准治疗方法,则可能需要进行另一个肌肉活检。这是为了检查包容体肌炎中发现的蛋白质。

Magnetic resonance imaging (MRI)

An MRI scan can help work out where the inflammation is. Sometimes MRI scans can pick up areas of muscle that are being replaced by fat, indicating damage.

MRI是一种使用磁铁来查看体内发生的事情的扫描。它可能显示出软组织损伤 - 在肌肉,韧带或神经中,以及骨骼的任何问题。

治疗

治疗for myositis includes a combination of drug treatment and exercise.

Drugs

The first choice of treatment of myositis issteroids, which are usually given in high doses to begin with.

Steroids can be given as tablets or injections. They should reduce the inflammation quickly, settle muscle pain and the feeling of being unwell.

High doses of steroids can have side effects, so your doctor will reduce the dosage as quickly as possible.

Taking steroids over a long time can increase the risk of developing the conditionosteoporosis, which causes bones to become thin and fracture more easily. There are drugs you can take alongside steroids to reduce the risk of developing osteoporosis. This includes bisphosphonates, which can slow bone loss.

Sometimes the symptoms of myositis can flare up when the steroid dose is lowered and your doctor may often prescribe other drugs to help reduce the inflammation. These includemethotrexate,azathioprine,ciclosporin, tacrolimus andmycophenolate

Most of these are types ofdisease-modifying anti-rheumatic drugs (DMARDs),您将需要定期进行血液检查以检查可能的副作用。

Occasionally these drugs aren’t able to control myositis. In these more severe cases, the following drugs might be available:

Biological therapies work by blocking specific targets within the immune system that cause inflammation.

Immunoglobulins are antibodies collected from blood donations given by healthy people, which can help stop your immune system from attacking your own tissues. This treatment is usually given as a drip into a vein in your arm, known as an intravenous drip. This will be carried out in hospital and it can be repeated if needed. Sometimes you might feel a little unwell, during the treatment itself.

即使在严重的情况下,肌炎通常会对治疗做出反应,尽管许多人需要终身药物治疗才能控制自己的病情。

运动和理疗

It’s probably best to rest when your myositis is very active, but once it has calmed down doing regular exercise can greatly improve your symptoms and overall health.

Aerobic exercise, which makes you breathe more heavily and your heart beat faster, is especially important to help restore muscle strength and improve stamina.

At first this should ideally be done under the supervision of aphysiotherapist, who’ll give you a tailored programme. You should avoid very strenuous exercise.

Children with juvenile dermatomyositis will need more vigorous physiotherapy to reduce the risk of joints, especially the knees, becoming permanently bent.

People with myositis can make a good recovery. However, some people with severe symptoms may never fully recover.

Even for people who do make a good recovery it can take several months to see improvement, as treatments take time to help your body repair muscles. Because of this you may experience a lot of tiredness.

继续尽可能定期运动将极大地帮助您的病情。

Research and new developments

Versus Arthritis has funded multiple research studies to further our understanding of myositis.

We’ve funded research to look at the link between genes people inherit, the presence of certain antibodies and the severity of their condition. This will allow doctors to predict which patients will experience mild or severe disease and why. This will help identify targets for future drug development.

We’ve also funded research to develop a standard method of assessing children with suspected juvenile dermatomyositis to improve diagnostic techniques, treatment and outcomes for young people. As these conditions are rare, research centres are joining forces to aid recruitment to clinical trials.

We are currentlysupporting several studies into juvenile dermatomyositisat our centre for adolescent rheumatology at Great Ormond Street Hospital, in London.

This research includes a study looking at the role of a specific white blood cell, a B cell, in myositis. Blood samples will be taken from young people with juvenile dermatomyositis and a group without the condition. The information gathered will improve our knowledge of the condition and may help to develop new and more effective treatments in the future.