Polymyositis: Causes, Symptoms and Treatments

Definition: is inflammatory myopathy.

Muscle diseases involve inflammation of the muscles or associated tissues, such as the blood vessels that supply the muscles.

A myopathy is a muscular disease, and inflammation responds to cell damage.

Another word for inflammatory myopathy is myositis. The root “mine” means muscle, and the root of “itis” means inflammation, So a myositis is an inflammatory muscle disease.

Polymyositis (PM) is found mainly in people older than 20 years and affects more women than men. Muscle weakness usually occurs for days, weeks, or months.

Weakness begins with the muscles closest to and within the body’s trunk. The neck, hip, back, and shoulder forces are an example.

Some patients also have weakness in the muscles furthest from the trunk, such as the hands and fingers. Some patients with PM experience muscle pain, breathing problems, and difficulty swallowing.


Researchers are finding that each case of PM is very different from the others. Sometimes, patients initially diagnosed with PM and not responding to treatment are later found to include body myositis.

Patients with certain types of PM may have one or more autoimmune diseases.

What are the symptoms?


  • Sudden or gradual weakness in the muscles.
  • Difficulty swallowing (dysphagia).
  • Fall and problems are getting up from a fall.
  • A general feeling of fatigue.
  • Chronic dry cough


Marked weakness in the muscles closest to the body’s center, such as the forearms, thighs, hips, shoulders, neck, and back.

Sometimes, weakness in the fingers and toes.

Thickening of the skin on the hands (mechanic’s hands).

The shoulders, upper arms, hips, thighs, and neck muscles show the most significant weakness with polymyositis.

There may also be pain or tenderness in the affected areas and problems with swallowing, and inflammation of the heart and lung muscle tissues.

Polymyositis is more common in women than men and usually begins after age 20. Over weeks or months, several muscles weaken and gradually weaken.

The most affected are the muscles of the hips and thighs, the arms, the upper part of the back, the area of ​​the shoulder, and the forces that move the neck.

Many people with PM have pain or tenderness in the affected areas. The person may have problems extending the knee or going down or climbing stairs.

Picking things up, fixing your hair, or putting things on a high shelf can be difficult. It can be challenging to lift the head of the bed when lying down.

PM can also affect the heart muscle, causing inflammatory cardiomyopathy.

The muscles involved in breathing can be affected, and some people develop some inflammation of the lung tissues themselves, another respiratory complication.

Of course, cardiac, respiratory, and swallowing problems are the most severe effects of PM and need close monitoring.

What causes polymyositis?

In most cases, the cause of inflammatory myopathy is unclear. The body’s immune system turns against its muscles and damages the muscle tissue in an autoimmune process.

In this disease, the inflammatory cells of the immune system directly attack the muscle fibers.

Polymyositis is not a genetic disorder, although there may be genetic factors that make it more or less likely that an inflammatory myopathy will develop.

In most cases, the cause of an inflammatory myopathy such as polymyositis is unclear. The body’s immune system turns against its muscles and damages the muscle tissue in an autoimmune process.

Viruses can be a trigger for autoimmune myositis. People with HIV, which causes AIDS, can develop myositis, just like people with HTLV-1. Some cases of myositis have followed the infection with the Coxsackie B virus.

There are reports of myositis after exposure to certain medications.

Among the drugs that are suspected of contributing to myositis is Caritas in (a local anesthetic), penicillamine (a drug used to reduce copper levels in the body), and interferon alfa (used primarily to treat cancer and hepatitis). ).

However, also cimetidine (to treat ulcers), carbimazole (to treat thyroid disease), phenytoin (used to treat seizures), and growth hormone.

The hepatitis B vaccine has also been implicated in some cases.

Recent research suggests that mixing blood cells from a mother and fetus during pregnancy could lead to the subsequent development of an autoimmune disease such as myositis in the mother or child.

Although inflammatory myopathies such as polymyositis are not genetic, genetic factors may make it more or less likely to develop an inflammatory myopathy.

What is the status of research on this disease?

New research is rapidly leading to a greater understanding of polymyositis and more successful treatments. Scientists examine the factors that can cause this condition, such as viruses, certain medications, or vaccines.

All these factors are being studied so that inflammatory myopathies can be better understood, treated, or prevented altogether.

Scientists supported by MDA are studying the underlying mechanisms that cause inflammatory myopathies, the group of diseases to which polymyositis belongs.

Understanding precisely why and how the immune system attacks muscle tissue in polymyositis will likely lead to better treatments for the disease.

A research team is studying inflammatory myopathies in dogs.

These diseases appear to be similar in dogs and humans. It is believed that this project can generate a deeper understanding of human polymyositis and lead to new tools for diagnosis and treatment.

How is this disease treated?

Initially, polymyositis is treated with high doses of corticosteroids. Corticosteroids are cortisone medications (such as prednisone and prednisolone).

These are medications related to cortisone and can be administered orally or intravenously. They are recommended since they can have a powerful effect on decreasing the inflammation of the muscles.

They are usually required for years, and their continued use will be based on what the doctor finds related to the symptoms, examination, and blood analysis of the muscle enzymes.

Corticosteroids have many predictable and unpredictable side effects. In high doses, they commonly cause an increase in appetite and weight, swelling of the face, and easy bruising.

They can also cause sweating, beautiful facial growth, hair, upset stomach, emotions, leg swelling, acne, cataracts, osteoporosis, high blood pressure, worsening diabetes, and an increased risk of infection.

Uncommon effects of cortisone medications can cause severe bone damage (avascular necrosis) that can destroy large joints, such as the hips and shoulders. In addition, the sudden suspension of corticosteroids can cause outbreaks of the disease and cause other side effects, such as nausea, vomiting, and low blood pressure.

In addition, the sudden suspension of corticosteroids can cause outbreaks of polymyositis and cause other side effects, such as nausea, vomiting, and decreased blood pressure.