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An overview of the idiopathic inflammatory myopathies

Published on January 30, 2017 Reviewed on July 23, 2024   36 min

A selection of talks on Cardiovascular & Metabolic

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0:00
My name is Jemima Albayda. I'm an Assistant Professor at the Johns Hopkins University, seeing patients at the Division of Rheumatology, Myositis Center. Today, I will give you "An overview of the Idiopathic Inflammatory Myopathies".
0:17
Our objectives with this talk are to describe the clinical presentation of the idiopathic inflammatory myopathies. To define the subgroups of myositis. And present the framework for current understanding of classification. To enumerate the known antibody associations. And discuss how they help guide prognosis and management. To detail the clinical evaluation of myositis and the role of ancillary testing. And to briefly discuss treatment strategies.
0:47
The idiopathic inflammatory myopathies are a rare group of acquired autoimmune muscle disorders. Clinically, they are characterized by muscle weakness and by inflammatory cell infiltrates in the muscle. Although, it is thought of as a muscle disorder, it is quite heterogenous in presentation and treatment response. Extramuscular manifestations are often seen and can include skin and lung inflammation, joint, heart, and rarely GI tract involvement. There's also a known increased risk of malignancy, particularly, in cases of dermatomyositis.
1:28
When we think about how these diseases present, certain features are often considered. There's usually symmetrical weakness, usually progressive of the limb-girdle muscles, such as the deltoids and hip flexors. There's elevation of serum levels of muscle-associated enzymes, such as creatine phosphokinase, aldolase, LDH, and AST, and ALT. There can be muscle biopsy evidence of myositis. And this can include necrosis of type I and type II muscle fibers, phagocytosis, degeneration and regeneration of myofibers, and infiltrates, which are inflammatory involving the endomysial, perimysial, perivascular, interstitial spaces. There is also often electrophysiologic evidence of myopathy. And these can include short, small, low-amplitude polyphasic motor units potentials, positive fibrillation potentials, even at rest, and bizarre high frequency repetitive discharges. In the case of dermatomyositis, characteristic rashes are often seen. These features I mentioned make up the core set of the most commonly used and widely accepted criteria for myositis,

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