18- MUSCLE DISORDERS

• Myalgia


  Muscle symptoms without increased serum CK levels
• Myositis


  Muscle symptoms + elevated CK levels, after excluding causes of high CK
• Myopathy


  Primary functional or structural impairment of skeletal muscle, which can be acquired or hereditary
• Differential Diagnosis of Myopathy


  • Drugs - statins, steroids
  • Infections - bacterial- staph-, strep-, pneumococcus, salmonella, tuberculosis, CMV, EBV, HIV, Herpes simplex, Cryptococcus, trichinosis, toxoplasmosis
  • Metabolic – glycogen storage disease
  • Sarcoidosis
  • Endocrine Hypo/Hyperthyroid, Hyperparathyroidism, Cushing, Vit D deficiency
  • Neuromuscular Disorders
  • Fibromyalgia
  • Myofascial Pain Syndrome
  • Polymyalgia Rheumatica
  • Chronic Fatigue Syndrome
• Fibromyalgia


  • Chronic widespread pain (≥3 months) & ≥ response to pressure
  • 9 times more common in females
  • Pain in at least 11 out of 18 tender points
  • Fatigue, sleep disturbances, cognitive depression
  • Partially respond to exercise & Amitriptyline
• Myofascial pain syndrome


  • Unbearable pain from one point of body to next
  • Deep aching muscle pain, joint stiffness, areas of tension (knot-like feeling)
  • Sites: arms/ legs, neck & back, buttocks, + many referred trigger points
  • Treatment: analgesia, antidepressants, muscle relaxants, physiotherapy, acupuncture
• Polymyalgia rheumatica


  • Periarticular pain (shoulder & hips)
  • Bilateral aching & stiffness
  • Morning stiffness > 1 hour
  • Fatigue, loss of appetite, weight loss
  • VERY HIGH ESR
  • 15% of PMR have giant cell arteritis
  • 50% of GCA have PMR
  • Respond to prednisolone (decrease symptoms in 24 to 48 hours)