Polymyositis is a condition caused when the skeletal muscles—the muscles that allow your body to move—become irritated and inflamed. The muscles eventually start to break down and become weak, making even simple movements difficult. Medically, polymyositis is classified as a chronic inflammatory myopathy — one of only three such diseases. Polymyositis rarely strikes people younger than 18, but it mostly affects adults in their 30s, 40s or 50s. Experts are of the opinion that polymyositis is probably triggered by a viral infection or an autoimmune reaction—a response that causes the body to attack its own tissues. In some cases, certain medications may lead to an allergic response that cause muscle irritation and damage. Many people with polymyositis show a detectable level of auto antibodies in their blood. Most of the time, however, doctors aren’t able to uncover the exact cause of polymyositis.
Your doctor may run a number of different tests to diagnose polymyositis. Elevated muscle protein levels in the blood reflect muscle irritation and can help to establish the diagnosis of polymyositis. In addition, a physical exam and special tests to determine how strong your muscles are can also be helpful. Polymyositis can also be diagnosed with the help of these tests such as MRI scans, Biopsy of muscle tissue and Electromyography which tests muscle strength and function by examining its electrical activity.
Polymyositis can’t be cured, but treatments can manage symptoms. Steroids drugs are the primary treatment for polymyositis. Symptoms usually get better within four or six weeks, and your doctor will usually start to cut down on the steroids after that to minimize possible side effects. Some people may need to take steroids permanently to manage the disease and keep symptoms at bay. Steroid medications aren’t always effective though. In some instances, a doctor may prescribe special drugs that blunt the immune system and help reduce the inflammation associated with polymyositis.
Physical therapy and regular exercise can also help treat polymyositis and treat symptoms. These approaches can help keep muscles from shrinking, or becoming atrophied, and can help maintain your strength. Using heat therapy on the muscles and taking some time to rest can also help symptoms improve.
In addition to a thorough physical exam, the doctor will likely use other tests to confirm a diagnosis of polymyositis such as:
Magnetic resonance imaging (MRI): to create cross-sectional images of the muscles from data generated by a powerful magnetic field and radio waves.
Electromyography: Electrical activity is measured as the muscles tighten or relax, 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.
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.
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.