Polymyositis

more about Polymyositis

Also known as

Proximal muscle weakness or Neuromyositis

Description

  • 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).
  • 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.

Symptoms

  • 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

Cause

  • Unknown (not certain)
  • Possible causes:
  • Viral (virus) Infections such as HTLV1
  • Autoimmune — body’s natural defenses (white blood cells and antibody Proteins) attack the muscles for unknown reasons
    1. There may be an abnormal inherited gene involved.

How the diagnosis is made

    • 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:
  • Blood tests for evidence of muscle inflammation and damage (myositis) — Creatinine kinase levels (a muscle chemical) are elevated
  • Blood levels of other chemicals (enzymes) such as SGOT, LDH, Aldolase, and ESR (elevated in inflammation) may also be elevated.
  • Blood may test positive for RF (rheumatoid antibody), ANA (lupus antibody), myositis, and other antibodies (body Proteins that fight off foreign invaders).
  • Blood tests may show anemia (low blood) and increased number of white blood cells.
  • A urine sample may show Myoglobin, a muscle pigment released when the muscle is damaged.
  • Chest X-Ray may show changes in the lungs known as interstitial fibrosis.
  • EKG — measures electrical activity of the heart — done if Arrhythmias (irregular heart rhythm) is suspected.
  • EMG — measures muscle electrical activity — abnormal in Polymyositis.
  • Muscle biopsy may show characteristic changes consistent with Polymyositis.
    1. 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.

Risk Factors

  • 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:
  • Alcohol — ethanol
  • Corticosteroids
  • AZT
  • Chloroquine
  • Tryptophan
  • Lovastatin
  • Cholchicine
    1. Vaccine injury

Treatment

  • 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.

If You Suspect this Condition

  • Contact your physician. Ask about new treatments, ongoing research protocols, or clinical trials.

Similar Conditions

  • Drug-induced muscle weakness (see risk factors)
  • Autoimmune disorders:
    1. Rheumatoid Arthritis
    2. SLE (lupus)
    3. Myasthenia Gravis
    4. Polymyalgia Rheumatica
  • Eaton-Lambert syndrome.