[Importance of inflammatory myopathies in practice]

Inflammatory myopathies can be subdivided into two main groups: infectious (bacterial, viral or other) myositis and immunogenic myositis. According to their frequency there are four main groups of diseases: dermatomyositis (DM), overlap syndromes, inclusion body myositis (IBM), idiopathic polymyositis (PM). Muscle weakness and atrophy are the prominent clinical symptoms of all immunogenic inflammatory myopathies. Muscle pain is not so common and occurs more frequently in acute forms than in chronic cases. Primary chronic forms of polymyositis and inclusion body myositis are mostly painless. Diagnosis starts with electromyography and laboratory investigations (especially CK). Myositis associated antibodies are mostly associated with acute forms. Radiological methods, especially MRI, are important in chronic cases. Definite diagnosis has to be done by muscle biopsy. Immunohistological (especially in DM and PM) and ultrastructural (especially in IBM) techniques are necessary in some cases. Concerning therapy of DM and PM, corticosteroids in combination with immunosuppressive drugs are effective in most cases. Intravenous immunoglobulins are needed only in selected cases (severe forms), side effects of therapy or resistance to conventional therapy. In IBM, it is the only therapeutic possibility, especially in young patients with rapid progression of the disease.