Current concepts in the idiopathic inflammatory myopathies: polymyositis, dermatomyositis, and related disorders

Article Abstract:

Idiopathic inflammatory myopathies are rare autoimmune diseases where inflammation occurs in the skeletal muscles and the muscles become weak and degenerate. In most cases, the causes of the disease are not known, although drugs, toxins, and some infectious agents have been known to cause them. Idiopathic inflammatory myopathies includes polymyositis (inflammation of many muscles), dermatomyositis (a disease of the connective tissues, characterized by eczematous inflammation of the skin and weakness of the muscles), cancer-related myositis, connective tissue disease-associated myositis and childhood dermatomyositis, treatment-resistent inclusion body myositis and other related disorders. A conference at the National Institutes on Health was held in April 1988 and a summary of the meeting is presented. The clinical symptoms are described, with the main features being weakness, muscle tenderness, occasional pain, muscle atrophy or degeneration, and fibrosis, the development of fibrous tissue in the muscle. It is necessary for a muscle biopsy to be taken for the proper diagnosis to be made, so that inflammatory myopathy can be distinguished from neuromuscular disorders. The diseases can affect other parts of the body outside of the skeletal muscles, and can have effects on the heart and lungs, the oropharyngeal cavity, the gastrointestinal tract, and the endocrine, or hormone-producing, system. The involvement of the disease in the heart and lungs can lead to lung disease, irregular heart beat and heart attack. It is thought that genetic predispositions of individuals and the exposure to environmental agents, such as drugs, toxins or various infectious agents, act together to cause idiopathic inflammatory myopathies. There is evidence that picornaviruses can initiate the diseases in some individuals. Studies have revealed that autoantibodies, which are directed against some normal component of the body, are involved in these diseases. Treatment includes the administration of corticosteroids, to which most patients respond initially, and cytotoxic drugs if the patient no longer responds to the corticosteroids. Newer treatments are being developed. (Consumer Summary produced by Reliance Medical Information, Inc.)

Causes of, Autoimmune diseases, Muscle diseases, Muscular diseases

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Controlled trial of plasma exchange and leukapheresis in polymyositis and dermatomyositis

Article Abstract:

Leukapheresis (removal of white blood cells) and plasma exchange may not be effective for treating patients with polymyositis or dermatomyositis that is resistant to treatment with corticosteroids. Polymyositis and dermatomyositis are inflammatory diseases that affect muscle throughout the body. Of 39 patients with polymyositis or dermatomyositis resistant to treatment with corticosteroids, 13 were treated with leukapheresis, 13 were treated with plasma exchange and 13 were not treated. Three patients from each group experienced improvement of muscle strength and function after treatment. But there was no significant difference in muscle strength or function between patients in the three treatment groups. The condition of three patients treated with leukapheresis and one treated with plasma exchange worsened, but the condition of the other 26 patients did not change.

Health aspects, Polymyositis, Plasma exchange (Therapeutics), Leukapheresis

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Myositis: immunologic contributions to understanding cause, pathogenesis, and therapy

Article Abstract:

The discovery that many patients with myositis produce antibodies that attack normal body proteins may help researchers learn about the disease. Myositis or idiopathic inflammatory myopathy is an inflammation of muscle tissue. Patients with this rare disease have muscle pain and weakness in the trunk, limbs, and neck as well as signs of muscle damage. Many patients with polymyositis or dermatomyositis produce antibodies against proteins called synthetases that are present inside all body cells. Research indicates that T-cells may play a role in myositis. Environmental factors may stimulate the immune system and trigger the onset of myositis in susceptible people. Corticosteroids and other agents that modulate the immune system are prescribed to treat myositis. Myositis follows a similar course in adults and children, although it occurs less frequently in youngsters.

Research, Autoantibodies, Physiological aspects

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