Myopathies Flashcards
Autoantibody associated with aggressive polymyositis pooly responsive to immunosuppression
Anti SRP
Dermatomyositis
Anti-synthetase
Anti-Jo1 - associated with ILD
Anti-Mi2
anti-SRP
Cancer associated: anti-TiF gamma, anti-NPX-2
Diagnosis of Mixed Connective Tissue Disease
Diagnosis of Myositis
Anti U1 RNP suggests MTCD, but not diagnostic (Anti-68 kD and A’ antibodies more specific)
ANA may be present with very high titre with speckled pattern
Anti-Smith or anti-dsDNA should suggests SLE rather MCTD though this can transiently occur
Name the different skin manifestations of dermatomyositis
Describe the characteristic cutaneous manifestations of dermatomyositis
May accompany or precede muscle weakness
- possible to present without weakness: dermatomyositis in myositis, where muscle biopsy still demonstrates significant changes
Skin findings:
- heliotrope rash
- gottron’s sign - scaly violacious rash over bony protuberances, especially the knuckles
- V or shawl sign - both may worsem with sun exposure
- mechanics hands
- dilated naiofold capillary loops
Which inflammatory myositis has the highest association with cancer?
Dermatomyositis
What are the clinical features common between the inflammatory myopathies?
Polymyositis and dermatomyositis are symmetrical, over weeks to months
- Inclusion body myositis can be asymmetrical, over years
Usually present with difficulty performing tasks requiring proximal muscles
- fine motor tasks deteriorate late in PM/DM but can be early in IBM
Ocular muscles are never involved
All often affect pharyngeal and neck flexor muscles
- characteristic ‘head drop’
Severe weakness almost always with muscle wasting
- sensation always preserved
- may lose reflexes in severe atrophy but should be preserved
Myalgia mainly in DM associated with CTD
How does inclusion body myositis (IBM) present? Does it have any associations?
Most common inflammatory myopathy in those >50yrs
- In contrast to PM and DM, characteristically affects BOTH proximal and distal muscles
- may be symmetric or asymmetric
- slow and steady disease progression: most need gait aid within a few years of diagnosis
- >=20% associated with systemic autoimmune or CTD
- Also associated with HIV and HTLV-1
Weakness and atrophy of distal muscles in almost all cases
- especially foot extensors and deep finger flexors
- can’t hold objects, tie knots, turn keys
Shrinking, atrophic forearm is characteristic
Falls due to early quadriceps weakness
- falling and tripping are classic
Dysphagia common (~60%)
- can lead to choking
May have mildly diminished vibratory sensation at the ankles, presumed age related
