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| == Myositis == | | == Myositis == |
| Myositis is a subtype of myopathy where there is inflammation of muscle.
| | {{#lst:Inflammatory myopathy|neurology}} |
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| === Etiology ===
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| * Polymyositis (PM)
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| * Dermatomyositis (DM)
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| * Necrotising myositis
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| * Inclusion body myositis (IBM)
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| * Overlap myositis
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| * Paraneoplastic myositis
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| Dermatomyositis and necrotising myositis can be primary or secondary to adenocarcinoma.
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| === Clinical features ===
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| In most types of myositis there is proximal weakness, atrophy, and muscle pain. The only exception is inclusion body myositis, in which there is distal muscle weakness. IBM affects elderly.
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| In dermatomyositis there are also skin symptoms, namely heliotrope rash and Gottron papules. Polymyositis is like dermatomyositis but without skin symptoms. Necrotising myositis is similar to them but worse.
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| === Diagnosis and evaluation ===
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| The creatine kinase (CK) is elevated in most cases. MRI can show the distribution and extent of inflammation and can guide the location for biopsy.
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| Muscle biopsy is usually required for diagnosis. On muscle biopsy, inflammation, and MHC-I expression (which is usually not expressed on muscle) can be seen. In necrotising myositis, necrosis can be seen, and in IBM, vacuoles are present.
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| EMG can differentiate between neurogenic and myopathic problems.
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| In dermatomyositis and necrotising myositis it’s important to rule out adenocarcinoma.
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| === Treatment ===
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| The treatment is usually immunosuppressants, usually steroids + azathioprine or methotrexate. Immunosuppressants is not effective for IBM, however.
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| [[Category:Neurology 2]] | | [[Category:Neurology 2]] |
