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| Polymyositis/Dermatomyositis |
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Polymyositis - Also Known As
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Proximal muscle weakness or Neuromyositis
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Description
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• Polymyositis is the inflammation (i.e., irritation, pain, swelling, and damage) of the muscles closest or proximal to the trunk of the body (i.e., limb girdles, neck, and pharynx). It is a progressive condition, with periods of relapse (gets worse) and remissions (gets better).
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• There is an adult form of Polymyositis in those between 40-60 years old, and a childhood form seen in those between ages 5-15. Polymyositis can also occur with other inflammatory type diseases (e.g., Rheumatoid Arthritis, mixed connective tissue diseases, and dermatomyositis) as well with some malignancies.
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Symptoms
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• First, may notice muscle aches and pain
• Weakness and fatigue
• Often affects arms and legs
• Heliotrope rash may be seen around the eyes, knuckles, and nail beds
• Swelling around the eyes
• Progressive difficulty getting up from the chair or bed
• Difficulty with climbing stairs
• Difficulty raising arms -- e.g., combing hair, brushing teeth.
• Difficulty kneeling
• Muscle and joint pain, stiffness, and tenderness
• Trouble swallowing
• Breathing difficulties
• Heart problems -- swollen ankles, shortness of breath, fatigue, irregular heart rate
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Causes
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• Unknown (not certain)
• Possible causes:
1. Viral (virus) Infections such as HTLV1
2. Autoimmune -- body's natural defenses (white blood cells and antibody Proteins) attack the muscles for unknown reasons
3. There may be an abnormal inherited gene involved.
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How The Diagnosis Made
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• History:
1. Symptoms
2. Illnesses
3. Medications
4. Surgeries
5. Allergies
6. Occupation
7. Habits
8. Family history
• Medical exam will demonstrate the presence of heliotrope rash and Proximal Muscle Weakness (arms and legs).
• The doctor may refer patient to a neurologist (muscle and nerve doctor) or a rheumatologist (muscle and joints doctor).
• Often tests are needed for diagnosis:
1. Blood tests for evidence of muscle inflammation and damage (myositis) -- Creatinine kinase levels (a muscle chemical) are elevated
2. Blood levels of other chemicals (enzymes) such as SGOT, LDH, Aldolase, and ESR (elevated in inflammation) may also be elevated.
3. Blood may test positive for RF (rheumatoid antibody), ANA (lupus antibody), myositis, and other antibodies (body Proteins that fight off foreign invaders).
4. Blood tests may show anemia (low blood) and increased number of white blood cells.
5. A urine sample may show Myoglobin, a muscle pigment released when the muscle is damaged.
6. Chest X-Ray may show changes in the lungs known as interstitial fibrosis.
7. EKG -- measures electrical activity of the heart -- done if Arrhythmias (irregular heart rhythm) is suspected.
8. EMG -- measures muscle electrical activity -- abnormal in Polymyositis.
9. Muscle biopsy may show characteristic changes consistent with Polymyositis.
10. Muscle biopsy -- surgically taking a tiny piece of the affected muscle and looking at it under a regular or even an electron (very powerful) microscope.
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Risk Factors
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• Female > Male (2:1 ratio)
• Family history of Polymyositis, vasculitis, or other autoimmune disorders
• Dermatomyositis -- Polymyositis with a purplish skin rash (heliotrope)
• Bacterial, viral, and parasitic infections
• Genetic -- association with HLA - DR3, HLA - DRw52 genes
• Certain drugs and medications:
1. Alcohol -- ethanol
2. Corticosteroids
3. AZT
4. Chloroquine
5. Tryptophan
6. Lovastatin
7. Cholchicine
8. Vaccine injury
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Treatment
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• Usually outpatient
• Involves reducing inflammation with drugs, such as:
1. Prednisone
2. Azathioprine
3. Methotrexate
4. Cyclosporin A.
5. Cyclophosphamide
6. Other medications or combinations can be added.
• Intravenous (via blood) immunoglobulins (antibodies) are added to Prednisone therapy in some instances to enhance the effect in resistant cases.
• A search for cancer is recommended in all adults with Polymyositis.
• Those with thin bones, as demonstrated by a bone mineral density test, need to be closely observed while taking steroids (Prednisone, etc.), and supplemented with bone-building medications, Calcium, and vitamins.
• Exercise and physical therapy is recommended to prevent joint damage and keep up strength.
• Psychiatric counseling may be needed if the patient is depressed.
• Cardiologist (heart doctor) or a pulmonologist (lung doctor) may be consulted as needed.
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If You Suspect This Condition
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• Contact your physician. Ask about new treatments, ongoing research protocols, or clinical trials.
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Similar Conditions
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• Drug-induced muscle weakness (see risk factors)
• Autoimmune disorders:
1. Rheumatoid Arthritis
2. SLE (lupus)
3. Myasthenia Gravis
4. Polymyalgia Rheumatica
• Hypothyroidism -- low levels of thyroid hormone
• Eaton-Lambert syndrome
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What is Dermatomyositis?
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Dermatomyositis is one of a group of acquired muscle diseases called inflammatory myopathies. The disease, which has a somewhat severe onset, affects both children and adults. Females are more often affected than males. Dermatomyositis is characterized by a rash accompanying, or more often, preceding muscle weakness. The rash looks like patchy, bluish-purple discolorations on the face, neck, shoulders, upper chest, elbows, knees, knuckles, and back. Some people may also develop calcium deposits, which appear as hard bumps under the skin. The most common symptom is muscle weakness, usually affecting the muscles that are closest to the trunk of the body. Eventually, people have difficulty rising from a sitting position, climbing stairs, lifting objects, or reaching overhead. In some cases, muscles further away from the trunk of the body may be affected later in the course of the disease. Problems with swallowing (dysphagia) may occur. Occasionally, the muscles ache and are tender to the touch. Affected individuals may also feel fatigue and discomfort and experience weight loss or a low-grade fever.
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Is there any treatment?
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Prescribing a steroid drug, such as prednisone, is usually the first line of treatment. Immunosuppressants, such as azathioprine and methotrexate, may help those for whom prednisone is ineffective. Further treatment with intravenous immunoglobulin was shown to be effective and safe. Physical therapy is usually recommended to preserve muscle function and prevent muscle wasting.
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What is the prognosis?
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Most cases of dermatomyositis respond to therapy. The disease is usually more severe and resistant to therapy in individuals with cardiac or pulmonary problems.
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What research is being done?
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The NINDS conducts and supports a broad range of research on neuromuscular disorders such as inflammatory myopathies. Basic science research and clinical studies are designed to increase understanding of the disorders and, ultimately, to find ways to prevent, treat, and potentially cure them.
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