How is it Diagnosed??

In some children, the signs of JDMS develop over a long period of time. In others, the signs develop quickly. To find out if your child has JDMS, the doctor will ask about your child's health history, perform a complete physical examination, and obtain laboratory tests.

Child's Health History

The doctor will ask many questions about your child's symptoms, such as:

•When did the symptoms start?
•What parts of the body are involved?
•Are the symptoms always present, or present only at certain times?
•Are the symptoms getting better or worse?
•How are your child's activities affected by the illness
•Has she had any choking or regurgitation
•Can she carry her back pack and books

The doctor may also want to know if other members of the family have had arthritis or a muscle disease since, in rare instances, some forms of these illnesses may run in families.

Physical Examination

The doctor will examine your child, paying special attention to skin and muscles. In particular, the doctor will look for these signs:

•a rash on the face, knuckles, elbows, knees, and/or cuticles
•swelling around the eyes
•nasal speech pattern
•sore and/or weak muscles
•sore and/or swollen joints
The doctor will carefully check your child's strength and will check routine areas, such as the eyes, ears, nose, and throat. The strength exam is extremely important; your doctor will ask your child to lift her arms, legs or head and then see if she can hold them up against the doctor's resistance. Only with a proper muscle exam can the weak muscles be identified as weak. Your child will develop all kinds of movements to hide her disability. One of the things you should look for in your doctor is his or her ability to show you your child's weakness.

Laboratory Tests

Laboratory tests help determine if your child has JDMS. These tests show if there is inflammation in the muscles or in other areas of the body. Many of these tests may be abnormal early in the course of the illness, even if your child has only mild muscle weakness. The most common tests are:

Muscle Enzymes

When the muscles are inflamed or damaged, certain proteins from inside the muscle cells (called enzymes) leak into the blood stream and their levels can be measured. The doctor will look for these enzymes such as CPK and aldolase. Your doctor may also tell you about other enzymes, called AST, ALT and LDH. These are less specific than CPK and aldolase but are often used to assess how medications are working. If large amounts of these enzymes are found in the blood, then the doctor knows that some muscles have been damaged.

Antinuclear antibodies (ANA)

This test shows whether or not your child's immune system is producing antibodies against the body's cells. This is not a specific test for DMS, it is often positive in other rheumatic diseases.

Electromyogram (EMG)

This test measures electrical activity in the muscles. Children with JDMS have a specific electrical pattern that shows the muscle is inflamed.

In this test, a thin needle is placed through the skin and into the muscle. A wire runs from the needle to a machine that records electrical activity in the muscle. Unfortunately, it is painful and therefore it is not done frequently.

Muscle Biopsy

This test provides the most specific information about your child's inflamed muscles. It shows how much the muscles or blood vessels have been affected by the disease. If your child needs a biopsy, the doctor will remove a small piece of muscle and look at it and its surrounding blood vessels under a microscope to see if there is any inflammation.

Most doctors no longer perform EMG or muscle biopsy if the child has a typical rash, demonstrable muscle weakness during the physical examination, and elevated muscle enzymes in the blood test. However, if there is no rash, or muscle enzymes are normal despite a typical rash, EMG and/or muscle biopsy is needed.

MRI (magnetic resonance imaging)

MRI, a very sophisticated Xray, is sometimes done to find inflamed muscles in children who remain strong and have normal or just slightly elevated levels of muscle enzymes; the MRI helps identify muscles most suitable for biopsy.

By putting together the story of how the illness started with the results of the physical examination and the laboratory tests, the doctor can usually make the proper diagnosis.

NOTE: Juvenile dermatomyositis (JDMS) affects 3,000 to 5,000 children in the United States. While certain signs and symptoms are common in most children with JDMS, the disease affects different children in different ways. The following information describes the general symptoms of and treatment for JDMS, but it is important for you to discuss your child's particular case with your doctor.


http://www.arthritis.org/disease-center.php?disease_id=37&df=diagnosed