• See Also
  1. Polymyositis
  2. Dermatomyositis
  • Pathophysiology
  1. Group I of Polymyositis disorders (accounts for 33%)
  • Epidemiology
  1. Incidence higher in women by ratio of 2:1
  • Course
  1. Insidiously progressive over weeks to years
  • Symptoms
  • Proximal limb weakness
  1. Hip and Thigh weakness (Most significant)
    1. Difficult rising from seated/kneeling position
    2. Difficult climbing/descending stairs
    3. Unable to walk (5%)
  2. Shoulder Muscle Weakness
    1. Difficulty reaching overhead (e.g. combing hair)
  3. Buttock, thigh, or calf aching (10%)
    1. Tenderness to palpation (20%)
  • Symptoms
  • Other
  1. Dysphagia (25%)
  2. Weakness of extensor neck Muscles
  3. Respiratory Impairment (5%)
  4. Cardiac involvement (30%)
    1. Electrocardiogram (EKG) change or Arrhythmia
    2. Congestive Heart Failure secondary to Myocarditis
  • Signs
  1. Proximal Muscle Weakness
  2. Distal Muscle sparing in 75%
  3. Muscles tender to palpation with signs of atrophy
  4. Gait slow and waddling
  • Differential Diagnosis
  1. See Polymyositis Differential Diagnosis
  • Evaluation
  1. See Polymyositis Evaluation
  • Management
  1. See Polymyositis Management
  • References
  1. Koler (2001) Am Fam Physician 64(9):1565-72 [PubMed]