Inflammatory Myopathies: Symptoms, Treatment
Overview
Inflammatory myopathies consist of polymyositis (PM) dermatomyositis (DM) and inclusion body myositis (IBM). They are a group of muscle diseases that involve inflammation of the muscles and associated tissues.
Myopathy is also known as inflammatory muscle disease or myositis. It is sometimes caused by the body’s misdirected attacks on muscles, resulting in inflammation, hence the name of inflammatory myopathy. Muscle weakness and soreness are the main characteristics of the condition. If left untreated, loss of muscle bulk (atrophy) may occur.
Inflammatory myopathies can occur in about 1 person per 100,000. They can affect people in all age groups, but children aging 5 to 10 and adults between 40 and 50 years old are more likely to get myopathy than others. Women are at a higher risk of developing the disease than men. The exact cause of inflammatory myopathy is unknown, but you can have a good outcome following your doctor’s treatment plan carefully.
Cause
In most cases, the cause of an inflammatory myopathy is unclear. For some reason, the body’s immune system attacks its own muscles and damages muscles and tissues.
Virus might be a trigger for this kind of autoimmune response. For example, people with the HIV virus, which causes AIDS, can develop a myositis. Other factors, such as muscle injury due to medicine, inherited diseases that affect muscle function, disorders of electrolyte levels, and thyroid disease, can play roles in the affection of this disease.
Risk factors for inflammatory myopathy include age and gender. Children between 5 and 10 years and adults aging 40-50 may be at a greater risk than people in other age groups. Women are two times more likely to get a myositis than men. Ethic group is not a risk factor in this disease.
Symptoms
There are three different types of inflammatory myopathies: PM, DM and IBM. Each of them have signs and symptoms different or similar to another. General manifestations of inflammatory myopathy include:
- Muscle weakness and inflammation in the neck, shoulders or hips
- Muscle pain
- Shortness of breath
- Trouble climbing stairs, getting up from a seat, or reaching for objects overhead
- Choking while eating food into the lungs
- Cough
In patients with DM, skin rash may occur. Children with inflammatory myopathy may have calcinosis, meaning white calcium deposits in the skin.
Diagnosis
First, doctors will examine your medical history and symptoms developing in your body. To confirm the diagnosis, doctors will do some further tests. They include:
- Electromyography (EMG).
EMG can record the electrical activity generated by muscles during contraction and at rest. It can detect the muscle proteins produced by muscle cells when these cells are electrically or neurologically activated. Normally, muscle cells are inactivated.
- Blood tests to check if there are elevated levels of muscle enzymes and autoantibodies
- Ultrasound to look for muscle inflammation
- Magnetic resonance imaging (MRI) to reveal abnormal muscle anatomy
- A biopsy of affected muscles to examine signs of chronic inflammation, muscle fiber death, vascular deformities, or other changes
- A skin biopsy when skin rash appears to show changes associated with DM
Treatment
Inflammatory myopathies cannot be entirely cured but many of the symptoms can be treated through proper treatment plans. In normal conditions, doctors would suggest that you combine medications and physical therapy.
Medications used to treat inflammatory myopathies are:
High doses of corticosteroid drugs, such as prednisone, are usually the first treatment option for patients with inflammatory myopathies. They can effectively reduce inflammation. But certain side effects do present, including weight gain, thinning of the skin, osteoporosis, and cataracts, sometimes even muscle weakness.
- Immunosuppressant drugs, like methotrexate or azathioprine to better control the disease in the long term and help avoid long-term side effects of corticosteroids
- Other immunosuppressive agents to treat the inflammation associated with DM and PM, such as tacrolimus (Prograf), mycophenolate mofetil (CellCept), and rituximab (Rituxan)
Intravenous immunoglobulin is recommended for patients who do not respond to the above-mentioned drugs or cannot tolerate them.
Physical therapy is usually used to prevent muscle atrophy as well as to maintain muscle strength and range of motion.
Keywords: inflammatory myopathies; myositis; polymyositis (PM); dermatomyositis (DM); inclusion body myositis (IBM).
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