Definition

What is polymyositis?

Polymyositis is an idiopathic inflammatory myopathy that causes symmetrical, proximal muscle weakness; elevated skeletal muscle enzyme levels; and characteristic electromyography (EMG) and muscle biopsy findings. Polymyositis can make it difficult to climb stairs, rise from a seated position, lift objects or reach overhead. Clinically similar to polymyositis, dermatomyositis is an idiopathic, inflammatory myopathy associated with characteristic dermatologic manifestations. Inclusion body myositis is a slowly progressive, idiopathic, inflammatory myopathy with characteristic pathologic findings that is generally found in older males

How common is polymyositis?

Polymyositis most commonly affects adults in their 30s, 40s or 50s. It’s more common in blacks than in whites, and women are affected more often than men. Polymyositis signs and symptoms usually develop gradually, over weeks or months.

Please discuss with your doctor for further information.

Symptoms

What are the symptoms of polymyositis?

The muscle weakness associated with polymyositis involves the muscles closest to the trunk, such as those in your hips, thighs, shoulders, upper arms and neck.

The weakness affects both the left and right sides of your body, and tends to gradually worsen.

When should I see my doctor?

If you have any signs or symptoms listed above or have any questions, please consulting with your doctor. Everyone’s body acts differently. It is always best to discuss with your doctor what is best for your situation.

Causes

What causes polymyositis?

The exact cause of polymyositis is unknown, but the disease shares many characteristics with autoimmune disorders, in which your immune system mistakenly attacks your own body tissues.

 

Risk factors

What increases my risk for polymyositis?

Risk factors for developing polymositis are:

  • Advanced age
  • Female sex
  • African American race
  • Interstitial lung disease
  • Presence of anti-Jo-1 (lung disease) and anti-SRP antibodies (severe muscle disease, cardiac involvement)
  • Associated malignancy
  • Delayed or inadequate treatment
  • Dysphagia, dysphonia
  • Cardiac and pulmonary involvement

Diagnosis & treatment

The information provided is not a substitute for any medical advice. ALWAYS consult with your doctor for more information.

How is polymyositis diagnosed?

If your doctor suspects you have polymyositis, he or she might suggest some of the following tests:

Blood tests

A blood test will let your doctor know if you have elevated levels of muscle enzymes, such as creatine kinase (CK) and aldolase. Increased CK and aldolase levels can indicate muscle damage. A blood test can also detect specific autoantibodies associated with different symptoms of polymyositis, which can help in determining the best medication and treatment.

Electromyography

A doctor with specialized training inserts a thin needle electrode through the skin into the muscle to be tested. Electrical activity is measured as you relax or tighten the muscle, and changes in the pattern of electrical activity can confirm a muscle disease. The doctor can determine the distribution of the disease by testing different muscles.

Magnetic resonance imaging (MRI)

A scanner creates cross-sectional images of your muscles from data generated by a powerful magnetic field and radio waves. Unlike a muscle biopsy, an MRI can assess inflammation over a large area of muscle.

Muscle biopsy

A small piece of muscle tissue is removed surgically for laboratory analysis. A muscle biopsy may reveal abnormalities in your muscles, such as inflammation, damage or infection. The tissue sample can also be examined for the presence of abnormal proteins and checked for enzyme deficiencies. In polymyositis, a muscle biopsy typically shows inflammation, dead muscle cells (necrosis), and degeneration and regeneration of muscle fibers.

How is polymyositis treated?

Although there is no certain cure for polymyositis, treatment can improve your muscle strength and function. The earlier treatment is started in the course of polymyositis, the more effective it is — leading to fewer complications.

However, as with many conditions, no single approach is the best. Based on your symptoms and how well they respond to therapy, your doctor will tailor your treatment strategy.

Medications

Some common medications are used to treat polymyositis include:

  • Corticosteroids

Drugs such as prednisone can be very effective in controlling polymyositis symptoms. But prolonged use of these drugs can have serious and wide-ranging side effects, which is why your doctor may gradually taper the dose of medication down to lower levels.

  • Corticosteroid-sparing agents

When used in combination with a corticosteroid, these drugs can decrease the dose and potential side effects of the corticosteroid. The two most common medications used for polymyositis are azathioprine (Azasan, Imuran) and methotrexate (Trexall).

  • Rituximab (Rituxan)

More commonly used to treat rheumatoid arthritis, rituximab is an option if initial therapies don’t adequately control your polymyositis symptoms.

Therapy

Depending on the severity of your symptoms, your doctor might suggest:

  • Physical therapy

A physical therapist can show you exercises to maintain and improve your strength and flexibility and advise an appropriate level of activity.

  • Speech therapy

If your swallowing muscles are weakened by polymyositis, speech therapy can help you learn how to compensate for those changes.

  • Dietetic assessment

Later in the course of polymyositis, chewing and swallowing can become more difficult. A registered dietitian can teach you how to prepare easy-to-eat foods.

Surgical and other procedures

  • Intravenous immunoglobulin (IVIg)is a purified blood product that contains healthy antibodies from thousands of blood donors. These healthy antibodies can block the damaging antibodies that attack muscle in polymyositis. Given as an infusion through a vein, IVIg treatments are expensive and may need to be repeated regularly for the effects to continue.

Lifestyle changes & home remedies

What are some lifestyle changes or home remedies that can help me manage polymyositis?

There is no certain prevention for polymyositis. When the precise cause of polymyositis is identified, preventative measures might be possible.

If you have any questions, please consult with your doctor to better understand the best solution for you.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Sources

Review Date: July 31, 2017 | Last Modified: July 31, 2017

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