How are these disorders treated?

The chronic inflammatory myopathies cannot be cured in most adult patients but many of the symptoms can be treated.  Options include medication, physical therapy, exercise, heat therapy (including microwave and ultrasound), orthotics and assistive devices, and rest.  Inflammatory myopathies that are caused by medicines, a virus or other infectious agent, or exposure to a toxic substance usually abate when the harmful substance is removed or the infection is treated.  If left untreated, inflammatory myopathy can cause permanent disability.

Polymyositis and dermatomyositis are first treated with high doses of prednisone or another corticosteroid drug.  This is most often given as an oral medication but can be delivered intravenously.  Immunosuppressant drugs, such as azathioprine and methotrexate, may reduce inflammation in patients who do not respond well to prednisone.  Periodic treatment using intravenous immunoglobulin can further recovery in patients with dermatomyositis or polymyositis.  Other immunosuppressive agents that may treat the inflammation associated with dermatomyositis and polymyositis include cyclosporine A, cyclophosphamide, and tacrolimus.  Physical therapy is usually recommended to prevent muscle atrophy and to regain muscle strength and range of motion.  Bed rest for an extended period of time should be avoided, as patients may develop muscle atrophy, decreased muscle function, and joint contractures.   A low-sodium diet may help to counter edema and cardiovascular complications.

Many patients with dermatomyositis may need a topical ointment (such as topical corticosteroids or tacrolimus) or additional treatment for their skin disorder.  A high-protection sunscreen and protective clothing should be worn by all patients, particularly those who are sensitive to light.  Surgery may be required to remove calcium deposits that cause nerve pain and recurrent infections.

There is no standard course of treatment for IBM.   The disease is generally unresponsive to corticosteroids and immunosuppressive drugs.  Some evidence suggests that intravenous immunoglobulin may have a slight, but short-lasting, beneficial effect in a small number of cases.  Physical therapy may be helpful in maintaining mobility.  Other therapy is symptomatic and supportive.