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Ask the Expert: Myositis

white blood cells

In this week’s installment of Ask the Expert, Dr. Lindsay Lally, Rheumatologist, answer questions on myositis.

Q1. What is myositis?

Myositis means inflammation of the muscles. There are many causes of myositis including:

  • Infection
  • Drug or medication side-effects
  • Trauma
  • Cancer
  • Autoimmune disease

The inflammatory myopathies are a group of autoimmune muscle diseases involving chronic muscle inflammation. The most common inflammatory myopathies are dermatomyositis and polymyositis. Patients with other autoimmune disorders, such as systemic lupus erythematous or scleroderma, can also have myositis as part of their disease.

Q2. What are the effects of myositis?

If left untreated, the muscle inflammation in myositis can lead to permanent muscle damage and loss of muscle mass. Myositis can be associated with problems in other organs like the joints and the lungs. In dermatomyositis, there is usually a rash or skin inflammation in addition to the muscle inflammation.

Q3. What are some signs and symptoms of a flare?

There are many signs and symptoms of a flare for myositis patients. They include:

  • Muscle weakness is the most common symptoms of myositis
  • Fatigue, fevers or weight loss
  • Blood tests show increased muscle enzymes like creatine kinase (CK)
  • New or worsening rash in patients with dermatomyositis
  • Shortness of breath or cough in myositis patients with lung involvement

Q4. How can it be diagnosed?

Patients with myositis usually complain of muscle weakness, particularly in the proximal muscle groups like the deltoids and the quadriceps. A doctor can often detect and quantify the degree of muscle weakness with a simple physical exam. Blood tests will usually show high levels of muscle enzymes in the circulation, which is a sign of muscle breakdown and damage. There are also some specific blood tests for autoantibodies that may be present in patients with inflammatory myopathies. Your doctor may order an MRI or ultrasound to look for evidence of inflammation in the muscle. Another test called an electromyograph (EMG) can provide information about muscle injury. The gold standard to diagnosis myositis is to perform a muscle biopsy which can demonstrate inflammatory changes in the muscle tissue.

Q5. What are some forms of treatment?

Polymyositis and dermatomyositis are treated with medications to suppress the immune system in order to stop inflammation. Corticosteroids, like prednisone, are often prescribed at first because they can act quickly to quell the inflammation. Depending on symptoms, disease severity, and other organs involved, additional immunosuppressive medications either in pill or intravenous form may be recommended. Physical therapy or a structured exercise program can be very helpful too in order to regain muscle strength.

Reviewed on July 16, 2018.

Dr. Lindsay Lally specializes in the care of patients with various rheumatic conditions including vasculitis, systemic lupus erythematosus, scleroderma, and rheumatoid arthritis and has a particular interest in the systemic vasculitides. Dr. Lally is actively involved as an investigator in numerous clinical and translational studies focusing on vasculitis and has been the recipient of several awards including a Vasculitis Foundation Research Grant and the American College of Rheumatology Distinguished Fellow Award.

The information provided in this blog by HSS and our affiliated physicians is for general informational and educational purposes, and should not be considered medical advice for any individual problem you may have. This information is not a substitute for the professional judgment of a qualified health care provider who is familiar with the unique facts about your condition and medical history. You should always consult your health care provider prior to starting any new treatment, or terminating or changing any ongoing treatment. Every post on this blog is the opinion of the author and may not reflect the official position of HSS. Please contact us if we can be helpful in answering any questions or to arrange for a visit or consult.