Myositis is a rare condition that affects the muscles. The term myositis means "inflammation of the muscles" and it is usually caused by an underlying problem with the immune system, where it mistakenly attacks healthy tissue.

Types of myositis

There are different types of myositis which all affect the muscles, including:

  • polymyositis(PM)– which affects many different muscles, particularly the shoulders, hips and thigh muscles; it's more common in women and tends to affect people aged 30 to 60
  • dermatomyositis(DM) – which as well as affecting the muscles causes a rash; it's also more common in women and affects both adults and children
  • post-infectious reactive myositis – which you can get after some viral infections and causes the muscles to become inflamed; this type of myositis is usually mild and settles without treatment
  • inclusion body myositis (IBM) – which causes muscle weakness in the quadriceps (main thigh muscles), weakness in the forearm muscles that flex the fingers, and weakness in the muscles below the knee, which can cause foot drop, making it difficult to lift the front part of your foot and toes and causing the foot to drag on the ground when walking; IBM is more common in men and tends to occur after the age of 50.

Although the condition affects adults and children, the childhood form possibly has different underlying causes and behaves somewhat differently from the adult form. Children can be expected to make a complete recovery. However, Myositis is a rare disease in any of its forms.

Symptoms of Myositis

In most of these conditions, the voluntary muscles break down due to inflammation. The main symptom of these illnesses is muscular weakness which can vary from week to week or month to month, although it tends to get worse without treatment. Other symptoms can include:

  • skin rash
  • muscle pain
  • fatigue
  • generally feeling unwell
  • trouble swallowing
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  • shortness of breath

People often have difficulty climbing stairs, rising from a seated position, turning over in bed, raising their arms over their head, and grasping items with their hands, and many become prone to falls. Symptoms can appear gradually, over a period of months or even years, or it may develop more rapidly, within days or weeks.

In addition to the above, with dermatomyositis, red or purple-coloured rash often appears on the face (eyelids, nose and cheeks), back, upper chest, elbows, knees and knuckles.

The rash can be itchy or painful, and you may also get hard lumps of tissue under the skin called calcinosis.

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The main signs are muscle weakness, painful or aching muscles, tripping or falling, and extreme tiredness after walking or standing. If you have any of these symptoms you should see your GP. Early detection and prompt treatment will provide people with the best possible chance of remission.

How do you get Myositis?

There may be a host of reasons why an individual develops Myositis, it is usually down to a number of factors both genetic and environmental, and nothing a particular individual has done themselves. Most doctors think that Myositis may be an autoimmune disease. Other doctors feel Myositis may be started by a virus or the combination of a viral infection and defective immune system.

Treating Myositis

There are a number of ways to treat myositis, although there are no specific treatments for it.

  • Exercise and physiotherapy might be prescribed according to your case
  • Steroids are the main type of medication used to treat polymyositis and dermatomyositis. They can include creams and tablets.
  • Disease-modifying anti-rheumatic drugs (DMARDs) such as azathioprine, methotrexate, cyclophosphamide or mycophenolate suppress your immune system and help reduce inflammation.
  • Intravenous immunoglobulin therapy may be needed in very severe cases of myositis where severe muscle weakness is causing life-threatening breathing or swallowing problems.
  • Biologic therapies, may also play a part in managing myositis in people whose symptoms don't respond to conventional steroids and immunosuppressive medication.

Myositis and Overlap Syndrome

As with most autoimmune diseases, Myositis seems to enjoy company. Overlap Syndrome is where a patient is diagnosed with two or more autoimmune diseases such as Scleroderma or Lupus.

The treatment of overlap syndrome is mainly based on the use of corticosteroids and immunosuppressants.

This information has been taken from NHS Choices, Myositis UK and Understanding

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