What is juvenile dermatomyositis? What are the signs and symptoms?
Juvenile dermatomyositis, or JM for short, is a disease found in children under the age of 18. JM affects 3,000 to 5,000 children in the United States. JM is thought to be an autoimmune disease. In an autoimmune disease, the body's immune system, which normally fights infections and diseases, fights the body's own tissues and cells. The immune system fights infections or injuries through inflammation (IN fluh MAY shun), or swelling.
The other forms of myositis (polymyositis and inclusion-body myositis) are not as common in children as in adults.
The first sign of JM is usually a skin rash. The rash may be red and patchy, like dry skin; a red or purplish color on the eyelids or cheeks that may look more like allergies; or both. JM patients can have weak muscles at the same time they see the skin rash, or the weak muscles may come after the rash over days, weeks or months. The weaker muscles are usually closer to the body (for example, neck, shoulders, back, and stomach), and you may notice your child having trouble climbing or standing from a seated position. The skin rash and weak muscles are caused by inflammation or swelling in the blood vessels under the skin and in the muscles, also called vasculitis (vas kyoo LIE tis).
Other signs may include falling, weaker voice [dysphonia (dis FOE nee yuh)], or problems swallowing [dysphagia (dis FAY jee yuh). About half of the children with JM have pain in their muscles.
Some children may have calcinosis (kal si NOH sis) or contractures (kun TRAK chers). Contractures happen when the muscle shortens and causes the joint to stay bent. Exercising the muscles can keep contractures from happening.
How will the doctor know my child has JM?
Your doctor may first ask you and your child questions about your child's health in general, including when you saw the first signs of weakness or rash. The doctor will also look at your child's skin and muscles, looking for signs of JM. Finally, the doctor may ask the hospital's lab to run one or more of the following tests:
Blood tests for muscle enzymes (including CPK and aldolase tests)
Muscle biopsy
Magnetic resonance imaging (MRI)
Electromyogram (EMG)
How can it be treated?
Most doctors first treat JM with prednisone (PRED ni zone), which is also called a steroid, corticosteroid, solumedrol, or prednisolone. Prednisone will slow the body's immune system since the immune system is attacking normal, healthy tissue. Side effects of prednisone include weight gain, mood changes, rounder face, and slowed growth. Prednisone also affects children's bones, so doctors may have them take a calcium supplement to help keep their bones healthy and strong.
Other possible medicines include methotrexate (METH oe TREKS ate); hydroxychloroquine (high DROKS ee KLOR oh kwine), also known as Plaquenil (PLA kweh nil); and cyclosporine (SIGH kloh SPOR en).
Doctors often work with Physical Therapists to find an exercise program that is right for each JM patient. Exercise helps the muscles and joints stay strong and flexible. A balanced and healthy diet is also important for the JM patient.
Talk with your doctor about JM. If your child has JM, it is important to start treatment as soon as possible. Patients who are diagnosed and treated quickly have better results in general.
The Myositis Association has a quarterly newsletter especially for JM families, with information for parents and special pages for your child. It is sent to every TMA member affected by JM.