Advances in diagnosis and management of inflammatory myopathies

Idiopathic inflammatory myopathies are rare causes of muscle weakness and may be difficult to diagnose and manage. The traditional classification of polymyositis (PM) and dermatomyositis (DM) has been expanded to include inclusion body myositis (IBM) and several other types as our knowledge of underlying immunopathologic mechanisms, specific antibodies, and clinical features has advanced. This has led to several modified and new classification systems and also to controversies over specific criteria required to make diagnoses of the several forms of inflammatory myopathies. The clinical response to treatment of PM and DM has been largely empiric, and IBM has proven to be refractory. There are efforts to formalize objective measures of treatment response to aid future randomized, controlled trials. This article reviews new information in the field of idiopathic inflammatory myopathies from the neurologic clinical perspective.