Myalgia

Differential Diagnosis

• Infection: Viral infection; Bacterial infection; Spirochete infection. E.g. Dengue fever; Trichinella infection Influenza virus.
• Drugs: Statins, Bisphosphonates, corticosteroids, ciprofloxacin, clofibrate, colchicine, chloroquine, emetine, aminocaproic acid, zidovudine, bretylium, penicillamine, drugs causing hypokalemia
• Metabolic disorders: Vitamin D deficiency; Mitochondrial myopathy; Scurvy; Osteomalacia
• Fibromyalgia
• Endocrine: hypothyroidism; hyperthyroidism; Cushing’s syndrome; Adrenal insufficiency; Hyperparathyroidism
• Polymyalgia rheumatica
• Rhabdomyolysis (and anything that can cause rhabdomyolysis)
• Myositis (muscle inflammation): e.g, polymyositis, dermatomyositis
• Systemic lupus erythematosus (SLE)
• Rheumatoid arthritis
• Inclusion body myositis
• Sarcoidosis
• Scleroderma
• Sjögren’s syndrome
• Psychiatric (e.g. somatic manifestations of depression)
• Domestic abuse; Crush injury
• Lyme disease
• Ehlers Danlos (Hypermobility syndrome)
• HIV myopathy
• Hypophosphatemia
• Hypokalemia
• Hypothermia
• Prolonged immobility, eg, after a drug overdose.
• Strenuous exercise (overuse) or heat stroke
• Seizure
• Severe volume contraction
• Alcoholism
• Muscular dystrophy, eg, Duchenne, Becker, limb-girdle, facioscapulohumeral (FSH); Myotonic dystrophy; Myotonia congenita
• Compartment syndrome; Muscle infarction
• Neuropathic
• Chronic fatigue syndrome
• Vasculitis
• Sarcocystosis
• Spinal stenosis
• Diabetic lumbosacral plexopathy

Evaluation

• Myalgias can be divided into diffuse (systemic) myalgias vs. Localized myalgias.
• Muscle pain can come from Rhabdomyolysis, Myositis, or Myopathy.