Causes and Diagnoses

Causes and Diagnoses of Complex Regional Pain Syndrome

Complex regional pain syndrome (CRPS) often develops after an injury to the arm or leg. The condition may occur after what seemed like a minor injury, such as a sprain. However, in CRPS, the pain persists long after the injury has healed.


There is no specific diagnostic test for complex regional pain syndrome. Making a firm diagnosis may be difficult early in the course of the disorder when symptoms are few or mild. The diagnosis is made after obtaining a complete medical history, performing a thorough physical examination and through observation of the following symptoms:

  • Presence of an initial injury
  • Higher than expected amount of pain from an injury
  • Change in appearance of the affected area
  • No other apparent cause of pain or altered appearance

A diagnosis can often be made if the patient has a history of a predisposing condition with typical symptoms and physical change in the painful region of the body. However, additional tests may be ordered to rule out other conditions.

Other tests may include:

  • Magnetic resonance imaging (MRI)
  • Triple phase bone scan
  • Nerve block

Diagnostic Tests