Inflammatory myopathies: pathogenesis, clinical presentation, diagnosis, treatment
The abrupt evolution of fundamental researches in medicine lets us combine new approach to ethiopathogenesis of a number of diseases such as inflammatory myopathies. Nowadays they are dived into five subtypes: dermatomyositis, polymyositis, necrotizing autoimmune myositis, inclusion-body myositis and overlap myositis. The differential diagnosis of the named clinical forms is a great challenge for the neurologists but the great value at the same time because each subtype of the disease is characterized with the unique pattern of the course and response to therapy. Thus the analysis of the contemporary data about these maladies, their clinical presentation and immunological peculiarities, determination of the rational therapy strategy looks to be very important point. So, the symptoms of dermatomyositis can be combined with manifestations of systemic sclerosis and mixed connective tissue disease; with typical cutaneous manifestations of inflammatory myopathies are short-lived or not clear. Polymyositis is often misdiagnosed with other diseases and subtypes of inflammatory myopathies: myositis with inclusions, autoimmune necrotizing myositis, muscular dystrophy. In this regard, polymyositis considered a diagnosis of exclusion and is best defined as subacute proximal inflammatory myopathy in adults, at which no lesions, family history of neuromuscular diseases, previous exposure miotoxic medications (statins, penicillamine, zidovudine et al.) and engage the front and extraocular muscles. Autoimmune necrotizing myositis is a distinct clinical and pathologic syndrome and can occur at any age, but is mostly seen in adults. It begins with a sharp, reaching its peak in a few days or weeks, or subacute, progressing steadily and causing severe weakness and very high levels of creatine kinase. Myositis with inclusions begins unnoticed and develops over a number of years, sometimes asymmetrical and has been steadily progressing, simulating the muscular dystrophies with late-onset or slow-progressive motor neuron disease. Cross myositis usually manifests without rash, which is a typical feature of dermatomyositis, but with severe pathological inflammatory changes in perifascicular, interfascicular and perimysial areas and are often associated with antisynthetased antibodies.