More In-depth Definition
What causes JDMS?
A new, really complete, description 1-9-02
Juvenile dermatomyositis (der-MA-toe-MY-o-SY-tis) (JDMS) is a relatively rare disease that causes a skin rash and weak muscles in children. JDMS is different from dermatomyositis in adults, and from polymyositis, a disease that usually affects adults.
The skin rash and weak muscles of JDMS are caused by inflammation in the blood vessels that lie under the skin and in the muscles. This is called vasculitis. Since blood vessels run throughout the body, JDMS can also affect other areas such as the digestive tract. Usually, the worst symptoms are in the skin and muscles.
JDMS is often called an autoimmune disease. The immune system is a group of cells which normally protects the body from infections. In autoimmune diseases, these cells are signaled to "turn on" their infection-fighting process, but then can't turn it off. The process then ends up damaging the body rather than protecting it.
One way the immune system cells fight infection is by a process called inflammation. But when the cells can't "turn off" the inflammation process, tissues are damaged. In JDMS, blood vessels in the skin and muscles are inflamed. An inflamed muscle will feel weak or sore, while inflamed skin will have a rash.
Juvenile dermatomyositis is a relatively rare disease characterized by myositis, a rash typically on the face and hands, edema, and vasculitis. Average age of onset is 8-9 years. The myositis causes symmetric muscle weakness, which is acute and rapidly progressive in 50% of cases, but can be indolent and associated with development of joint contracture before the diagnosis is made. Gower's sign (inability to rise from sitting on floor without using the hands) is often positive.
The typical rash is known as a "heliotrope" rash consisting of a purplish-red discoloration of the upper eyelids. Often there is periorbital and limb edema. The vasculitis can cause lesions in the skin, eye, GI tract, and myocardium (this can lead to varying degrees of heart block.) A late sign of the disease is muscle calcinosis, occurring in 2/3 of patients. Lung involvement is occasional; clinical hepatitis is not commented on in the literature, although nonspecific elevation of LFT's can be seen.
There is no clear gender predominance in juvenile dermatomyositis, whereas the adult form occurs more often in females. There is no association with underlying malignancy, which has been noted in the adult form.
Diagnosis is based on the above history and physical findings and by elevations in muscle enzymes, specifically CPK, aldolase, and alanine aminotransferase. ANA or Anti-DNA antibodies are often positive, however less consistently than in the adult form of the disease. Von Willebrand's factor antigen may be elevated, as in other types of vasculitis, and is useful for following the activity of the vasculitis.
Etiology is unclear, but seems to follow the model of genetic predisposition (HLA-B8, DR3, Q have been associated) with a superimposed insult that sets up a self perpetuating autoimmune reaction. There is evidence for Coxsackie B as an offending agent; less directly for echovirus.
Clinical course is variable, but general patterns include monocyclic with recovery in about 2 years, chronic polycyclic, and chronic continuous. Relapse is uncommon after a complete remission, however a few patients have been reported to develop scleroderma later in life. Calcinosis occurs months into the course, most often with the chronic forms of the disease. It is a factor in residual disability, as is development of muscle contracture. Deaths in juvenile dermatomyositis patients can be caused by acute myocarditis, severe myositis, bowel perforation from vasculitic ulcers, occasional lung involvement, and infection.
Treatment is controversial. The first line is usually pulse IV methylprednisone in doses of 30 mg/kg, up to 1 gram/day. For mild disease, some authors recommend qod oral prednisone alone or in combination with other agents. Cyclosporine A has shown promise as an adjunct therapy, although studies are quite small and important side effects are observed (hypertension, alopecia, renal insufficiency).
IVIG has proven very effective in several small studies, particularly in patients who develop steroid resistance or severe toxicity. The mechanism for its effect is unknown, but may include neutralization of viruses, suppression of autoantibody production and of cell mediated autoimmunity by masking epitopes, Fc receptors, etc. Finally, cytotoxic agents such as azathioprine, methotrexate, and cyclophosphamide are occasionally used in refractory cases.
How often and how long to treat must be individualized, and is particularly difficult in acute relapses in a chronic patient. Calcinosis has no specific therapy, but tends to improve with less active disease and increased patient mobility.
What causes JDMS?
It is not yet known what causes JDMS or what causes the immune system to damage the body. Many researchers now think the autoimmune reaction may be caused by the immune system's abnormal response to a virus. That is, immune system cells attack an invading virus, but then also attack the body's own tissue. It is now thought that the tendency for the immune system to react in this way may be at least partially inherited.
JDMS is not contagious. Children don't catch it from other children, and nothing can prevent a child from developing this disease.
Treatment for JDMS
There is no cure for JDMS, but treatment can prevent or control most serious problems. Each child's treatment plan will be based on the severity of the illness. The goal of any treatment program for JDMS are to:
To reach these goals, treatment usually includes:
As symptoms change, treatment plans may also change.
There are several medications doctors may use to treat JDMS. The specific drug or combination of drugs doctors use depends on the type and severity of the patient's symptoms. Since only common side effects of each drug are listed here, discuss your child's medication with the doctor.
Prednisone slows down the immune system and helps control inflammation in the muscles and joints. This drug is similar to cortisone, a natural body hormone. Prednisone is used to:
Dose: At first, high doses of this drug are given until the patient's muscle enzyme tests improve. As the patient gets better, the dose will gradually be lowered.
Common side effects: The side effects patients may have depend on how much medicine they take, and how long they have taken it. Common side effects include:
Over a long period of time, the drug can also cause these problems:
Prednisone may cause other side effects, depending on the dose and length of time the patient takes it. This drug is given because the benefits of controlling the JDMS outweigh the risks of side effects.
A word about relapses: As the prednisone dose is lowered, the patient's earlier symptoms of JDMS may return. This is called a relapse. These symptoms will usually go away with a mild increase of prednisone. Although some children have more than one relapse, a relapse may not necessarily slow the child's recovery from JDMS.
If prednisone alone can't control the child's illness, a stronger drug such as methotrexate or cyclophosphamide (Cytoxan) is often used. These drugs also slow down the body's immune system.
Dose: The doctor will use as little of these drugs as possible and will usually use them in combination with prednisone. The drugs are given as a pill or by injection. As your child gets better, the doctor will slowly reduce the dose of one or both of the drugs.
Common side effects: Because these drugs can cause serious side effects, they are used only of other medicines have not controlled the disease well enough. Talk to your doctor to decide whether the benefits of the drug outweigh the risk of its side effects. Side effects may include:
These side effects will go away when the dose is lowered or stopped completely. These drugs may cause other, more serious side effects. If your child is taking any of these drugs, the doctor will take regular blood and urine tests to monitor the drug's effect on your child.
Hydroxycloroquine (hi-DROCKS-ee-CLOR-o-kwine) is a drug sometimes used to treat a severe rash in JDMS. The brand name of this drug is Plaquenil (PLA-kewh-nill).
Dose: This drug is given as a pill. Since it simply controls the rash, your child will also take other medicines for other symptoms.
Common side effects: Side effects include:
A small dose of Plaquenil is given for JDMS, so eye problems don't happen very often. Plaquenil may cause problems such as focusing sharply on an object, or seeing a "halo" around lights. In the earliest stages of eye damage, the damage is still reversible. At this early stage, your child may not notice any symptoms. That is why an ophthalmologist (eye doctor who is an MD) should check your child's eyes every three to six months while your child is on Plaquenil. If eye problems are detected early, they should go away when the medication is stopped.
Exercise is a very important part of JDMS treatment: in fact, it is nearly as important as medication. The purpose of regular exercise is to:
A physical therapist can teach your child exercises to do at home. These exercises will be designed specifically for your child and will change depending on the activity of the disease. At first, your child's muscles may be weak and she may need help with the exercises. Later on, when your child won't need as much help, the exercises will be changed.
Exercises usually take about one hour per day. It is important for your child to do the exercises regularly, but not to overwork and tire her muscles. The therapist will try to combine some exercises with your child's normal play activity.
A Balanced Diet
Although there is no diet that will cure JDMS, it is important for your child to eat a regular, balanced diet. Protein in your child's diet is important for normal growth and to repair damaged muscles. Calcium is important for strong bones. If your child does not feel well and does not want to eat, try to keep her interested in foods by letting her help prepare meals, and by preparing many different foods.
Your local Arthritis Foundation (I received a booklet from my doctor, which is where
most of this information came from)
Vanderbuilt Medical Center (definition provided there)
Julia's JDMS Diary (Check out the Links section for a listing of many resourceful web sites)