II. Pathophysiology
- Group I of Polymyositis disorders (accounts for 33%)
III. Epidemiology
- Incidence higher in women by ratio of 2:1
IV. Course
- Insidiously progressive over weeks to years
V. Symptoms: Proximal limb weakness
- Hip and Thigh weakness (Most significant)
- Difficult rising from seated/kneeling position
- Difficult climbing/descending stairs
- Unable to walk (5%)
- Shoulder Muscle Weakness
- Difficulty reaching overhead (e.g. combing hair)
- Buttock, thigh, or calf aching (10%)
- Tenderness to palpation (20%)
VI. Symptoms: Other
- Dysphagia (25%)
- Weakness of extensor neck Muscles
- Respiratory Impairment (5%)
- Cardiac involvement (30%)
- Electrocardiogram (EKG) change or Arrhythmia
- Congestive Heart Failure secondary to Myocarditis
VII. Signs
- Proximal Muscle Weakness
- Distal Muscle sparing in 75%
- Muscles tender to palpation with signs of atrophy
- Gait slow and waddling