Myositis is the medical term for inflammation of the muscles. This inflammation may be the result of disease conditions that solely affect the muscles. It may also be a symptom of one or more diseases affecting the muscles and other areas of the body. Myositis may even be a side effect of medications.
Dermatomyositis
In dermatomyositis, people have muscle inflammation, right- and left-sided muscle weakness and skin disorders. Physicians currently do not know what causes this disease, according to David Hellmann, M.D., Chairman of the Department of Medicine at Johns Hopkins Bayview Medical Center. Physicians do know this disease affects people at any age, but those in their 50s and 60s are affected the most. Women are affected twice as often as men. The muscles in the neck, arms and legs gradually get weaker. The legs may become weak first, making it hard to get up from a chair or climb stairs.
Polymyositis
Polymyositis is caused by the immune system attacking the muscles instead of attacking foreign substances. As with dermatomyositis, people with polymyositis have a gradual weakness in the muscles of their neck, arms and legs. The leg muscles usually become weak before the arms, and this disease also primarily affects people in their 50s and 60s; twice as many women as men are affected. Unlike with dermatomyositis, people with polymyositis do not have any skin disorders in this disease.
Lipid-lowering Medications
Myositis is a rare side effect of "statin" medications. Myositis occurs more often in people who take several medications, have severe diseases or are elderly. The statin medications lower the low-density lipoprotein, or LDL, cholesterol level by as much as 60 percent, according to Anne Carol Goldberg, M.D., Associate Professor of Medicine at the Washington University School of Medicine. She notes in "The Merck Manual for Healthcare Professionals" that statins are HMG-CoA reductase inhibitors, which is short for hydroxymethylglutaryl-coenzyme A reductase inhibitors. These are enzymes, or proteins, which the liver must have to make cholesterol. Statins interfere with this enzyme, and this lowers a person's cholesterol levels.
Systemic Lupus Erythematosus
Systemic lupus erythematosus, or SLE, is a disease involving the immune system attacking its own cells and organs instead of only attacking foreign substances. Approximately 90 percent of people with this disease are women, reports Bevra Hahn, M.D., Professor of Medicine at the David Geffen School of Medicine, in "Harrison's Principles of Internal Medicine." At first, SLE may affect just one or more organs; but in time, people may develop myositis. Fever, weight loss, muscle aches, a facial rash that is sensitive to sunlight, anemia, a low number of white blood cells, neurological problems, heart abnormalities and kidney problems may also develop.
References
- "Current Medical Diagnosis & Treatment 2011"; Stephen McPhee, M.D., Maxine Papadakis, M.D.; 2011
- "Harrison's Principles of Internal Medicine"; Anthony Fauci, M.D., Dennis Kasper, M.D., Dan Longo, M.D., et al.; 2008
- The Merck Manual for Healthcare Professionals: Dyslipidemia (Hyperlipidemia)
