Muscle Disease Flashcards
List the muscle diseases
Polymyalgia Rheumatica
Polymyositis
Dermatomyositis
Fibromyalgia
What is polymyalgia rheumatica?
Chronic inflammatory condition of unknown aetiology causing proximal myalgia of the hip & shoulder girdles with morning stiffness lasting > 1 hour
Do the symptoms of polymyalgia rheumatica improve as the day goes on?
Yes they improve as the day goes on & with movement
Investigation of Polymyalgia Rheumatica
no specific diagnostic test
raised CPR, PV/ESR
Treatment of Polymyalgia Rheumtica
low dose steroids: prednisolone 15 mg daily, gradually reduced over 18 month
- symptoms respond dramatically
- sometimes diagnostic tool
Prognosis of Polymyalgia Rheumatica
By the end of treatment, the condition will have resolved in majority of the cases
What is the pathology of polymyositis?
Idiopathic inflammatory myopathy resulting in symmetrical, proximal muscle weakness
Proposed: T-cell mediated cytotoxic process against muscle antigens
AI response to nuclear & cytoplasmic autoantigens in 60-80% of patients with polymyositis & dermatomyositis
Histology of Polymyositis
Muscle fibres in varying stages of inflammation, necrosis, regeneration
CD8 T cells, macrophages surround healthy nonnecrotic muscle fibres
Symptoms of Polymyositis
Symmetrical proximal muscle weakness in upper & lower limvbs
insidous onset
difficulty with particular activities - e.g. climbing stairs
some have myalgia
dysphagia in 1/3rd (poor prognostic sign)
ILD in 5-30% (esp Anti-Jo)
Investigations of Polymyositis
Raised Inflammatory markers
CK raised (10x)
Immunology:
-ANA, anti-RNP (other AIs as well)
-Anti-Jo-I, Anti-SRP (unique to myositis)
EMG: abnormal in 90% - staging
muscle biopsy crucial (exclude other rare muscle diseases)
Treatment of Polymyositis
40mg prednisolone (initially) combined with methotrexate/azathioprine
Prognosis of Polymyositis
usually responds to treatment
30% with some residual weakness
What is dermatomyositis
Polymyositis (proximal symmetrical muscle weakness) + typical cutaneous features:
- Gottron’s papules
- Heliotrope rash
- V-shaped rash over chest
Investigation of Dermatomyositis
Raised Inflammatory markers CK raised (10x) Immunology: -ANA, anti-RNP (other AIs as well) -Anti-Jo-I, Anti-SRP (unique to myositis) EMG: abnormal in 90% - staging muscle biopsy crucial (exclude other rare muscle diseases) SCREEN FOR MALIGNANCY
Common cancers in patients with dermatomyositis
breast ovarian lung colon oesophagus bladder
