![]() Inflamatory myopathies are a group of muscle diseases involving the inflimation and degeneration of skeletal muscle tissues. They are thought to be autoimmune disorders. These include dermatomyositis, polymyositis and inclusion body myositis. Although all of these diseases result in muscle weakness, each is unique in its own development and treatment. 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.
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.
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.
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.
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.
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