POLYMYOSITIS Polymyositis is a disease of muscle featuring inflammation of the muscle fibers. The cause of the disease is not known. It begins when white blood cells, the immune cells of inflammation, spontaneously invade muscles. The muscles affected are typically those closest to the trunk or torso. This results in weakness that can be severe. Polymyositis is a chronic illness featuring progressive muscle weakness with periods of increased symptoms, called flares or relapses, and minimal or no symptoms, known as remissions. Polymyositis is slightly more common in females. It affects all age groups, although its onset is most common in middle childhood and in the 20s. Polymyositis occurs throughout the world. Polymyositis can be associated with skin rash and is then referred to as dermatomyositis. Dermatomyositis in children is referred to as juvenile dermatomyositis. Amyopathic dermatomyositis is the term used to describe people who have skin changes compatible with dermatomyositis but do not have diseased muscle involvement. Polymyositis can also affect other areas of the body and is, therefore, referred to as a systemic illness. Occasionally, it is associated with cancer or with other diseases of connective tissue (such as systemic lupus erythematosus, scleroderma, and rheumatoid arthritis). What are symptoms of polymyositis? Comment on this Read 8 Comments Share Your Story Weakness of muscles is the most common symptom of polymyositis. The muscles involved usually are those that are closest to the trunk of the body. The onset can be gradual or rapid. This results in varying degrees of loss of muscle power and atrophy. The loss of strength can be noticed as difficulty getting up from chairs, walking, climbing stairs, or lifting above the shoulders. Trouble with swallowing and weakness lifting the head from the pillow can occur. Occasionally, the muscles ache and are tender to the touch. Patients can also feel fatigue, a general feeling of discomfort, and have weight loss and/or low-grade fever. With skin involvement (dermatomyositis), the eyes can be surrounded by a violet discoloration with swelling. There can be scaly reddish discoloration over the knuckles, elbows, and knees (Gottrons sign). There can also be reddish rash on the face, neck, and upper chest. Hard lumps of calcium deposits can develop in the fatty layer of the skin, most commonly in childhood dermatomyositis. Heart and lung involvement can lead to irregular heart rhythm, heart failure, and inflammation of the lungs with shortness of breath. Because polymyositis can appear in combination with other illnesses (see related articles on systemic lupus erythematosus, scleroderma, and rheumatoid arthritis), it can also have overlap features with them. These illnesses are discussed elsewhere. Both polymyositis and dermatomyositis can sometimes be associated with cancers, including lymphoma, breast cancer, lung cancer, ovarian cancer, and colon cancer. The cancer risk is reported to be much greater with dermatomyositis than polymyositis. How does the doctor diagnose polymyositis? When a patient first sees the doctor, the recent symptoms especially concerning weakness will be discussed. The condition of many other body areas might be reviewed, for example, the skin, heart, lungs, and joints. An examination will further focus on these and other systems. Various measures of strength might be noted. The characteristic features of polymyositis include weakness of the muscles closest to the trunk of the body, abnormal elevation of muscle enzymes, electromyograph (EMG) findings, magnetic resonance imaging (MRI) findings, and certain abnormalities detected with muscle biopsy. Blood testing usually (but not always) reveals abnormally high levels of muscle enzymes, CPK or creatinine phosphokinase, aldolase, SGOT, SGPT, and LDH. These enzymes are released into the blood by muscle that is being damaged by inflammation. They can also be used as measures of the activity of the inflammation. Other routine blood and urine tests can also look for internal organ abnormalities. Chest X-rays, mammograms, PAP smears, and other screening tests might be considered. Autoantibodies can often be found in the blood of people with polymyositis. These include antinuclear antibodies (ANAs) and myositis-specific antibodies (such as Jo-1 antibody). An electromyograph (EMG) and nerve conduction velocity are electrical tests of muscle and nerves that can show abnormal findings typical of polymyositis as well as exclude other nerve-muscle diseases. Imaging of the muscles using radiology tests, such as magnetic resonance imaging (MRI scanning), can show areas of inflammation of muscle. This sometimes can be used to determine optimal muscle biopsy sites. A muscle biopsy is used to confirm the presence of muscle inflammation typical only of polymyositis. This is a surgical procedure whereby muscle tissue is removed for analysis by a pathologist, a specialist in examining tissue under a microscope. Muscles often used for biopsy include the quadriceps muscle of the front of the thigh, the biceps muscle of the arm, and the deltoid muscle of the shoulder.
Posted on: Mon, 08 Sep 2014 09:09:00 +0000
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