Complex Regional
Pain Syndrome

This relatively rare pain syndrome usually occurs from injuring the peripheral nerves that extend to the arms and legs. Within 24 hours after experiencing such an injury, a person may feel a severe burning pain in their hand or foot (depending on the nerve that is damaged), with increased pain from any stimulation to the area .

Over time, the affected limb can become cold and pale and undergo changes to the skin, hair and nails. Other symptoms include swelling, stiffness, increased or decreased blood flow due to dilation and constriction of vessels, changes in sweating, and tapered fingers. Once outward physical changes are noticeable, the condition may be irreversible.

Complex regional pain syndrome occurs in two forms, both similar but with different causes.

  • Type 1 (reflex sympathetic dystrophy syndrome) occurs when the nerves in the affected limb were not directly damaged and accounts for a predominant majority of people who experience complex regional pain syndrome.
  • Type 2 (causalgia ) occurs when an injury or illness directly damages the affected nerve and accounts for about one in every 10 cases of complex regional pain syndrome.

Diagnosing Complex Regional Pain Syndrome
No single test can definitively diagnose this condition. After performing a thorough medical history and physical examination, several tests may be ordered:

    • Bone scans  detect changes in the bone
    • Sympathetic nervous system tests look for disruption in nerve signaling
    • Thermography measures temperature differences across the affected limb
    • Sweat tests compare the amounts of salt chemicals in the affected and non-affected limb s
    • X-rays  determine loss of bone minerals
    • Magnetic resonance imaging  (MRI) shows any tissue changes.

Treating Complex Regional Pain Syndrome

In cases where treatment is started early, improvement and even remission are possible. Doctors use various medications to treat the symptoms of complex regional pain syndrome:

  • Over-the-counter pain relievers (aspirin, ibuprofen, naproxen), antidepressants and anticonvulsants (amitriptyline, gabapentin) and intravenous ketamine to alleviate pain
  • Corticosteroids (prednisone) to help reduce inflammation
  • one-loss medications (alendronate) to prevent or slow bone loss
  • Sympathetic nerve-blocking medications (anesthetic) to block pain fibers in affected nerves

Other beneficial therapies may include applying heat and cold to relieve swelling and sweating, topical analgesics to help reduce hypersensitivity, physical therapy to help decrease pain and improve range of motion and strength, transcutaneous electrical nerve stimulation (TENS) and spinal cord stimulation to apply electrical impulses to nerve endings to reduce pain and biofeedback.


Our physicians at Houston Methodist specialize in managing chronic pain conditions at the following convenient locations.