Inflammatory Myopathies Flashcards
what are inflammatory myopathies characterised by
muscle weakness
describe what myopathy is
literally means “muscle disease”, it is a disease of the muscle in which the fibres do not function properly
what are the main inflammatory myopathies
polymyositis and dermatomyositis
describe what type of disease polymyositis and dermamyositis are
they are idiopathic autoimmune diseases
what group of people are inflammatory myopathies most common in
female 2:1 male, and between 40-50 y/o
what do inflammatory myopathies increase the risk of
increased incidence of malignancy
risk greatest in men> 45
describe the clinical features of myositis
predominantly muscle weakness, myalgia(usually mild), often specific problems eg difficulty walking up stairs
describe the onset of myositis
insidious onset, worsening over months
what muscles are usually affected by myositis
often proximal muscles(eg shoulder, hip, thigh, chest), usually symmetrical
what is seen in dermatomyositis alongside the muscle issues
skin involvement
describe Gottron’s sign/papules seen in dermatomyositis
purple/red discolouration over backs of hands, over MCP and PIP joints
describe Heliotrope rash seen in dermatomyositis
purple/red discolouration around the eyes, sometimes along with eye oedema/swelling
describe what Shawl’s sign is in dermatomyositis
purple/red rash seen over back of shoulders and on the chest
what other organs can be involved in polymyositis and dermatomyositis
lungs(most common), oesophagus, heart
what systemic signs can be seen in dermatomyositis and polymyositis
fever, weight loss, Raynaud’s phenomenon, inflammatory arthritis
what lung involvement can be seen in poly- or dermato- myositis
interstitial lung disease(10% patients), less commonly respiratory muscle weakness
what oesophageal involvement may be seen in poly- or dermato- myositis
dysphagia
what cardiac involvement may be seen in poly- or dermato- myositis
myocarditis
describe what is confrontational testing in examination of inflammatory myopathies and what its used for
it is a direct test of power, checking the patients muscle power compared to your own by pushing against each other
what is isotonic testing in examination of inflammatory myopathies and what is it used for
30 second sit to stand test, to see if muscles fatigue over time
what is looked for in blood tests of inflammatory myopathies
creatine kinase(CK), inflammatory markers, autoantibodies, and then electrolytes, Ca etc to rule out other causes
what muscle enzyme is almost always raised in inflammatory myositis
creatine kinase(CK) (CRP often high also)
what are some specific autoantibodies associated with inflammatory myositis
ANA(anti nuclear antibody)(non-specific), anti-Jo-1(specific)
what other tests may be used in inflammatory myopathy investigation
electromyography(EMG), muscle biopsy, MRI
what would be seen on the electromyography(EMG) of a myositis patient
increased fibrillations, abnormal motor potentials, complex repetitive discharges
what is the definitive test used in diagnosis of myositis
muscle biopsy
what may be seen on an MRI of myositis
muscle inflammation, oedema, fibrosis and calcification
how is myositis treated
corticosteroids and immunosuppressants
describe the use of corticosteroids in myositis
orally given at start of treatment and gradually reduced, limit use if possible
what immunosuppressants may be used in myositis treatment
azathioprine, methotrexate, ciclosporin
what may be given if immunosuppressant drugs are not working in myositis
IV immunoglobin or
Rituximab(biologic therapy)
