Definition: is an inflammatory myopathy.
A group of muscle diseases that 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 is the response 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 trunk of the body. The muscles of the neck, hip, back and shoulder 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, cases originally diagnosed as PM and not responding to treatment are later found as inclusion 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 difficulty to get up from a fall.
- General feeling of fatigue.
- Chronic dry cough
Marked weakness in the muscles closest to the center of the body, 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 muscles of the shoulders, upper arms, hips, thighs and neck show the greatest weakness with polymyositis.
There may also be pain or tenderness in the affected areas, as well as problems of 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 a period of 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 muscles that move the neck.
Many people with PM have pain or tenderness in the affected areas. The person may have problems extending the knee, going down or climbing stairs.
Picking things up, fixing your hair or putting things on a high shelf can be difficult. It can be difficult to lift the head of the bed when lying down.
PM can also affect the heart muscle, causing a condition called 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 serious effects of PM and need close monitoring.
What causes polymyositis?
In most cases, the cause of an inflammatory myopathy is unclear. For some reason, the body’s immune system turns against its own 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. For some reason, the body’s immune system turns against its own muscles and damages the muscle tissue in an autoimmune process.
Viruses can be a trigger for autoimmune myositis. People with the HIV virus, which causes AIDS, can develop myositis, just like people with a virus called 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 are caritasin (a local anesthetic), penicillamine (a drug used to reduce copper levels in the body), interferon alfa (used primarily to treat cancer and hepatitis). ).
But 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, there may be genetic factors that make it more or less likely that an inflammatory myopathy will develop.
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 are examining 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 perhaps 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, and 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 to decrease 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 of 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.