About Myositis

A general term meaning inflammation of the muscles, myositis includes the following diseases:

• dermatomyositis

• inclusion body myositis

• juvenile myositis

• polymyositis

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The above diseases are also referred to as inflammatory myopathies.  They cause inflammation within muscle and muscle damage.

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Polymyositis, dermatomyositis, and juvenile myositis are all autoimmune diseases, meaning the body’s immune system is attacking the muscle.  While the immune system may also cause muscle damage in inclusion body myositis, this may not be cause of this disease. Although myositis is often treatable, these diseases are poorly understood and do not always completely respond to current medications.

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Muscle inflammation and damage may also be caused by certain medications.  These are called toxic myopathies.  Perhaps the most common toxic myopathy is caused by statin medications which are frequently prescribed to lower cholesterol levels.  In most cases, the muscle can recover once the problem medication is identified and stopped.

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Symptoms

Symptoms of myositis may include:

• trouble rising from a chair

• difficulty climbing stairs or lifting arms

• tired feeling after standing or walking

• trouble swallowing or breathing

• muscle pain and soreness that does not resolve after a few weeks

• known elevations in muscle enzymes by blood tests (CPK or aldolase)

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Although the inflammatory myopathies affect about 50,000 - 75,000 Americans, often they are not diagnosed correctly.  In part, this is because patients with autoimmune myopathies have many of the same symptoms as those with inclusion body myositis, toxic myopathy, or muscular dystrophies, which are inherited forms of muscle disease. In the case of inclusion body myositis, patients have been misdiagnosed with ALS.

 

As a result, patients with the above symptoms should be tested and evaluated by physicians and medical staff who specialize in diseases of the muscle. 

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