Difference between revisions of "Polymyositis"

(Text replacement - " prednisone" to " prednisone")
(Evaluation)
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==Evaluation==
 
==Evaluation==
*CBC, ESR, CRP, CK, UA, RF, ANA, Anti-Jo-1
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*CBC
 +
*ESR
 +
*CRP
 +
*CK
 +
*UA
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*Consider:
 +
**RF
 +
**ANA
 +
**Anti-Jo-1
  
 
==Management==
 
==Management==

Revision as of 21:24, 21 August 2016

Background

Idiopathic inflammatory myopathy causing symmetric proximal muscle weakness, elevated CK,and characteristic EMG findings

Clinical Features

  • Symmetrical proximal muscle weakness with insidious onset
  • Generally painless (though 30% have myalgia)
  • Difficulty with kneeling, climbing stairs, combing hair, or rising from a seated position
  • Weak neck extensors causing difficulty of holding head up
  • Associated arthralgias

Differential Diagnosis

  • Hypokalemia
  • Hypophosphatemia
  • Thyroid disorder (hypothyroidism or hyperthyroidism)
  • Myopathies
  • Inclusion body myositis
  • Drug Induced myopathies (EtOH, antimalarials, colchicine, antifungals)

Weakness

Evaluation

  • CBC
  • ESR
  • CRP
  • CK
  • UA
  • Consider:
    • RF
    • ANA
    • Anti-Jo-1

Management

  • Prednisone 1mg/kg/day for 4-8 weeks until CK returns to reference range
  • Other treatments that rheum may prescribe:
    • Methotrexate as second line for poor response to corticosteroids
    • Other agents with less evidence: IVIG, TNF Inhibitors

Disposition

  • Rheumatology or neurology consultation either in ED or as outpatient depending on severity of symptoms
  • Very strongly associated with malignancy (~30%), especially:[1]
    • Ovarian
    • Lung
    • Pancreatic
    • Stomach
    • Colorectal
    • Lymphoma
    • Bladder

References

  1. Hill CL et al. Frequency of specific cancer types in dermatomyositis and polymyositis: a population-based study. Lancet. 2001 Jan 13;357(9250):96-100.