Muscle Diseases Flashcards
Name 3 inflammatory myopathies?
- Polymositis
- Dermatomyositis
….both are idiopathic
- Polymyalgia rheumatica
Occurrence of polymyositis and dermatomyositis?
More common in females (2:1) with peak incidence at 40-50 years
Polymositis and dermatomyositis are assoc. with?
Increased incidence of MALIGNANCY, part. dermatomyositis
Histological features of polymyositis and dermatomyositis?
- Muscle fibre necrosis
- Degeneration and regeneration
- Inflammatory cell infiltrate i.e: the problem arises within the muscle ITSELF but the cause is unclear
Principal clinical feature of polymyositis and dermatomyositis?
MUSCLE WEAKNESS is the PRINCIPAL symptoms and has an insidious onset (over months)
Usually symmetrical and affecting the PROXIMAL muscles, so tops of arms and legs (drying/brushing hair, putting up washing, climbing stairs difficult due to weakness)
Other features in polymyositis and dermatomyositis?
Myalgia (muscle pain) CAN occur
Difference between polymyositis and dermatomyositis?
Dermatomyositis has signs of CUTANEOUS DISEASE
Cutaneous signs in dermatomyositis?
- Gottron’s sign (scaly erythematous papules or red patches overlying the MCP joints, elbows, and knees)
- Heliotrope rash (purple/red eyelids)
- Shawl sign (diffuse, flat, erythematous lesions over the back and shoulders, extending into a “V” on the upper chest; worsens with UV light)
Other organs affected by myositis?
Lungs (breathlessness may be caused by ILD or respiratory muscle weakness)
Oesophageal (dysphagia due to oesophageal and bulbar muscle inv.)
Cardiac (myocarditis)
Other systemic symptoms: fever, weight loss, Raynaud’s phenomenon, non-erosive polyarthritis (inflammatory)
Occurence of malignancy with polymyositis or dermatomyositis?
More common with dermatomyositis with the greatest risk in MEN > 45 YEARS
Tend to be ovarian, breast, stomach, lung, bladder and colon cancers
PMH assoc. with polymyositis or dermatomyositis?
Other autoimmune disease, such as diabetes mellitus and thyroid disease
DH assoc. with polymyositis or dermatomyositis?
Steroids
STATINS
SH assoc. with polymyositis or dermatomyositis?
Alcohol
Illicit drug use, esp. cocaine
Examination of polymyositis or dermatomyositis?
Confrontational testing - direct testing of power; will find that the person cannot resist the force pushing down on their arms and this is due to WEAKNESS
Isotonic testing (30 second sit and stand test); have the person cross their arms, to avoid help from upper limbs, and count how many times they can sit & stand in 30 secs
This is useful for monitoring the disease
Blood tests for polymyositis or dermatomyositis?
- Muscle enzymes, e.g: Creatine Kinase (CK) will be very high but it is non-specific
- Inflammatory markers will be raised
- Electrolytes, calcium, PTH, TSH to exclude other causes
- Auto-antibodies (ANA, Anti-Jo-1) - not present in all patients
Describe anti-Jo-1 antibodies
Myositis specific Ab that tends to be found in idiopathic inflammatory myopathies