Juvenile dermatomyositis (JDM)

The muscles and small blood vessels in the skin are affected which can cause muscle weakness and pain, and often affects the muscles of the torso, hips, shoulders and neck and on occasion blood vessels in organs.

At various periods in the progression of the disease, skin rashes can also occur on the knees, elbows, hands and faces and eyelids.

The disease progression of JDM generally follows three paths:

• One episode of disease that goes into remission within two years after onset.
• Disease alternates with long periods of remission and periods of relapse, which often occur when treatment is reduced or stopped.
• Chronic disease that is resistant to treatment with a higher risk of complication.

We have created videos to help children, families and teachers better understand the journey for children and young people with JDM.  The short videos can be seen on the PRN YouTube Channel.

• Fatigue that interferes with their daily activities
• Muscle pain and weakness often in the torso, abdomen, back and neck. This can result in reluctance to walk long distances, climb stairs or participate in sport.
• Inflammed muscles that can shorten and tighten over time, making straightening the effected limb/s difficult.
  Joint pain, swelling and stiffness caused by inflammation.
  Facial skin rash with distinguishing features of swelling around the eyes, a purple-pink discolouration on eyelids, and reddened cheeks.
• Rash and skin thickening on knuckles, knees and elbows that can develop before muscle pain or weakness. Some rashes get worse in the sun and others may develops associated sores and ulcers.
• Calcinosis (hard lumps containing calcium) can occur below the skin. Once these lumps have developed they are difficult to treat.
• Abdominal pain or tummy ache which can involve the bowels and cause constipation and discomfort.
• Breathing problems, swallowing difficulties and voice changes can occur because of muscle weakness. If there is inflammation of the lungs respiratory difficulties may be present.

Some JDM symptoms look like other diseases so diagnosis is made using physical examination and a range of laboratory tests. Your doctor will determine which tests are needed according to which symptoms are observed.

• Blood tests determine the levels of five muscle enzymes (CK, LDH, AST, ALT and aldolase) and various antibodies present in the blood. Commonly used to assess treatment and progress, blood tests are used throughout the treatment and management of the disease.
• Magnetic resonance imaging (MRI), electromyography and EMG can assist in diagnosis and to rule out other illnesses.
• Muscle biopsy involving the removal of a small piece of muscle for examination under a microscope is sometimes used to confirm diagnosis.

In some cases intravenous corticosteroids are given but if used in high doses over time these can cause side effects.

The most commonly prescribed medications are:

• Methotrexate
• Cyclosporin
• Mycophenolate mofetyl
• Intravenous Immunoglobulin (IVIg)
• Rituximab
• Cyclophosphamide is used in severe cases or those that have been hard to treat with other medications.

Other treatments

Physiotherapy and exercise is very important and an effective way to manage symptoms and disease progression. It helps maintain muscle strength and flexibility and is very effective in reducing stiffness and loss of mobility. Working in conjunction with a physiotherapist, significant improvements can be made from regular sessions of exercise. Parents and patient are shown stretches and strengthening exercises that can be done at home.

Intravenous Immunoglobulin (IVIG) is an intravenous treatment using human antibodies derived from blood to reduce inflammation. Some patients respond to IVIG better than others and the precise mechanism of how it works is unknown.

If you are using the internet to search for information about your child’s disease, in addition to the excellent Australian resources listed, we recommend information provided by Paediatric Rheumatology InterNational Trials Organisation (PRINTO)

PRINTO is an international public network of academic and/or clinical centres engaged in the research and clinical care of children with paediatric rheumatic diseases. They collect a lot of information world-wide and so the information they provide is reliable and up-to-date.