Objective: Polymyositis (PM) and dermatomyositis (DM) are inflammatory muscle diseases of presumed autoimmune origin. Many possible interventions are available to treat these patients: corticosteroids, immunosuppressive drugs, plasmapheresis, and total body irradiation. But these therapies are not always effective and may be responsible for certain serious side effects. Polyvalent intravenous immunoglobulin (IVIG) has been tried with success in inflammatory myopathies after failure of traditional treatment. An attempt was made to evaluate the efficacy of IVIG as first line therapy in patients with PM or DM.
Methods: Eleven Caucasian patients [6 women, 5 men, mean age 55.6 (SD 10.1) years], with active recent inflammatory myopathy, were treated by high doses of IVIG as first choice. The average duration of inflammatory myopathy before IVIG was 9.6 months (SD 10.2 months, with a range of 1 month to 3 years). Five patients had PM and 6 had DM. None had myositis associated with connective tissue disease. Two patients had a history of malignant disease: 1 lymphoma and 1 breast tumor with relapse of the malignancy during the study. One patient had a probable lung carcinoma and in another patient, ovarian carcinoma was diagnosed a few months after the onset of IVIG. We used preparations of polyvalent human i.v. gamma globulins with intact IgG. All patients received 1 g/kg daily for 2 days each month. The mean course of treatment was 4 months.
Results: Clinical assessment, evaluated by proximal muscle power and biochemical tests, was carried out before each treatment period. Significant clinical improvement was noted in only 3 of the 11 patients (one with acute coxsackie virus B infection, and one with possible drug induced myopathy). Mean muscle power estimated for the 11 patients before and after IVIG therapy was not significantly improved. Eight patients showed significant biochemical improvement (more than 50%). Mean CK levels for the 11 patients showed a statistically significant decrease during IVIG therapy (p < 0.01). Minor IVIG side effects were noted in one patient.
Conclusion: IVIG therapy seems effective rarely as first therapy in patients with inflammatory myopathy but may be considered especially in viral or drug induced myopathy. IVIG therapy as the first treatment may also be tried in patients with contraindication for steroids, and in mild myopathy, especially in the elderly, to avoid steroid induced side effects.