Myositis
Myositis is the medical term used to define muscle soreness. In myositis, inflammation damages the muscle fibers, causing muscle weakness because it impedes the ability of muscle contraction. Although myositis can cause muscle pain and muscle tenderness, weakness is usually the dominant symptom.
In some cases, myositis is a short-term problem that goes away after a few days or weeks. In other cases, is part of a chronic (long). Chronic forms of myositis can lead to muscle atrophy (wasting and shrinking) and severe disability.
There are many different types of myositis, including:
Idiopathic inflammatory myopathies: In this group of muscle diseases of unknown cause muscle inflammation (idiopathic). There are three major types: dermatomyositis, polymyositis and inclusion body myositis. In the United States, idiopathic inflammatory myopathies affect about 1 in 100,000 people. Polymyositis and dermatomyositis are most common in women, whereas inclusion body myositis affects men more frequently.
Symptoms may begin at an early age, but the average age of first symptoms is premature cases of dermatomyositis and polymyositis (50 years) than in inclusion body myositis (60 years). To date, most evidence suggests that polymyositis and dermatomyositis are autoimmune disorders, diseases in which the immune system mistakenly attacks the body’s own cells. The muscles of people with inclusion body myositis contain abnormal protein called amyloid, but the reason is unknown form. This protein called amyloid is similar to the protein deposited in the brains of people with Alzheimer’s, and some experts believe that the two diseases might develop in the same way.
In inclusion body myositis, muscle contains tiny structures that resemble viral particles (called inclusion bodies), although viral infection has been identified associated with this disease. In dermatomyositis, cancer is found in approximately 10 to 20% of cases. Sometimes, the problem of the muscles is the first to be developed. In other cases, the cancer is detected before the myositis. Myositis quite similar to polymyositis or dermatomyositis, may accompany other autoimmune diseases like lupus erythematosus (SLE) or systemic sclerosis (also called scleroderma).
Myositis Infectious Myositis sometimes occurs as part of a systemic infection (whole body), especially a viral infection. It is especially common in people who had flu. Myositis is also caused by trichinosis, an infection in which tiny parasites invade the muscles. People can develop this infection by eating undercooked meat. One type of infectious myositis is called pyomyositis, a bacterial infection that causes one or more pockets of pus (abscesses) in the muscle. It is usually caused by Staphylococcus bacteria.
Pyomyositis is a relatively common infection in developing countries with tropical climates, especially in hygienic conditions and inadequate health care. However, cases sometimes appear in the U.S., especially in people who inject illegal drugs and in persons infected with HIV.
Benign acute myositis: In benign acute myositis, a young child suddenly develops severe leg pain and can not walk normally. These symptoms are dramatic, but usually disappear within a few days. Benign acute myositis usually occurs in children recovering from flu or respiratory infection is a problem caused by a virus. Doctors are not sure if the symptoms in the child’s muscles are caused by the virus itself or by the reaction of the body’s immune system to the virus.
Myositis ossificans: In myositis ossificans, a lump formed bone material (bone) into the muscle. This usually happens after a muscle injury, especially a deep bruise.
Drug-induced myositis: In the drug-induced myositis, muscle inflammation occurs as a side effect of medication or a combination of drugs. Although this is rare, the most common medications that cause myositis are those cholesterol-lowering drugs called statins, including atorvastatin (Lipitor), lovastatin (Mevacor) and simvastatin (Zocor) and zidovudine (Retrovir), also called AZT, a drug used to treat HIV / AIDS.
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