Inflamatory cells surround, imvade, and destroy normal muscle fibers as thought they were defective or foreign to the body. This results in muscle weakness. This muscle weakness is usually symmetrical and develops slowly over weeks to months or even years.

Early signs of inflamatory myopathies may include difficulty rising from a chair, climbing stairs, or lifting the arms. A patient can become exceedingly week after prolonged standing or walking. In some cases early signs may include difficulty in swallowing or breathing.

Tests that may be run include physical exam, blood tests, electromygraphy (EMG) and a muscle biopsy. The diagnosis is confirmed by the muscle biopsy using special strains. If a polymyositis patient does not respond to reatment it is important that they see a specialist to rule out IBM. At times a repeat muscle biopsy may be needed.







POLYMYOSITIS

Polymyositis-PM Onset of muscle weekness usually progresses slower then Dermatomyositis. Nearest to the trunk of the body, limb and neck muscles are weakened; invovement of muscles farthest from the trunk of the body varies. Difficulty in swallowing is common. Inability to breathe due to muscle fatigue is uncommon but occurs more often in PM than in Dermatomyositis or infusion body mysoitis. As many as one third of PM patients have muscle pain but is rarely the chief complaint.

It rarely affects people under the age of 20 but cases of childhood and infant PM have been reported. More women than men are affected with PM. High doses of Prednisone have been affective in treatment for many patients. Other nonsteriodal immunosupressants are also prescribed such as azathioprine and methotrexate are also prescribed. These drugs unfortunately have adverse side affects especially after prolonged use. For patients that do not respond well to prednisone intraveinous immunoglobulin might be effective.






DERMATOMYOSITIS

Dermatomyositis-DM is the most easily recognized due to its distincitve rash. The rash occurs as a patchy, dusky, reddish or lilac rash on the eyelids, cheeks, and bridge of the nose, and on the back or upper chest, elbows, knees, and knuckles. Some develop calcified nodules or hardened bumps under the skin. The rash often precedes mscle weakness.

Muscle weakness usually develops over a period of weeks but may develop over months or even days. The weakness initially affects those muscles closest to and within the trunk of the body, including the neck, hip, trunk and shoulder muscles. Difficulty swallowing occurs in at least one third of DM patients. Where as less then 25% of adults report mscle pain, more than 50% of children complain of muscle pain and tenderness.

DM can occur at any age. It is more common in females than males. High dose prednisone has been affective in the treatment of many patients. Other non steriodal immunosupressants such as azathioprine and methotrexate are often used. These drugs unfortunately have adverse side affects. For patients who do not respond well to prednisone intraveinous immunoglobulins has also proven affective.





INCLUSION BODY MYOSITIS

Inclusion body myositis-IBM is ver similar to PM. In fact many doctors believe that patients diagnosed with PM that do not respond to treatment actually may have IBM.The only definitive test for IBM is a muscle biopsy.

Onset of muscle weakness in IBM is usually very gradual, taking place over months or years. It is different from PM in that both proximal and distal muscles are affected. Typical findings include weakness of the wrist flexors and finger flexors. Atrophy or shrinking of the forearms is characteristic. In the legs, atrophy of the quadriceps muscle is common with varying degrees of weakness in other muscles.

Difficulty swallowing occurs in about half of patients with IBM. Facial muscle weakness is present in a minority of patients. Falling is often the first noticeable symptom of IBM.

Symptoms of IBM usually begin after age 50, although no age group is excluded. It occurs more frequently in men than women. About 1 in 10 causes of IBM may be hereditary.

There is no known treatment for IBM. Interveinous immnoglobulin has shown some preliminary evidence for a slight beneficial effect in a small number of cases. New drugs and other avenues are being explored. Prescribed physical therepy may be helpful to maintain mobility.





JUVENILE MYOSITIS

Juvenile idiopathic inflamatory myopathy-JIIM or juvenile myositis-JM most often presents itself as dermatomyositis-JDM with its typical rashe and muscle weakness. There are fewer cases of juvenile PM-JPM, inclusion body myositis-JIBM and other clinical forms of myositis reported. The JDM rash preceeds muscle weakness greater than 50% of the time. In both cases JPM and JDM muscle weakness usually develops over a period of months, weeks or days. The weakness being closest to and withing the trunk of the body primarily involves neck, hi9p, trunk and shoulder muscles. May also include distal muscles, difficulty swallowing, hoarseness, abdominal pain, and arthritis can also occur with this disorder. Muscle pain is seen approximately in 50% of children with myositis.

Corticosteriods are effective in the majority of patients and remission with complete withdrawl of medication can be anticipated in a large percentage of patients. Patients with severe weakness may need longer periods of treatment. For those patients that experience dose-limiting side effects of corticosteroids or are unresponsive, there are other treatments available, including intrveinous immune globulin infusions.

It is important to diagnose these patients and start treatment as soon as possible. The patients and the doctor of a child with myositis will also want to consider a rehabilitation program with a team of professional experts in this fiels.