Complex regional pain syndrome (CRPS) is a chronic pain condition characterized by severe pain, swelling, and changes in the skin, such as the pigmentation and/or texture. 

Previously known as reflex sympathetic dystrophy (RSD), CRPS most commonly develops in an arm or a leg, typically after surgery or as a result of an injury (i.e. a broken bone or sprain). It is a condition that may subsequently spread throughout the body.


Other events or conditions that can trigger CRPS include: brain diseases, such as stroke; degenerative arthritis of the neck; and heart disease. Though more uncommon, patients may also experience CRPS without being able to identify the event or injury that triggered it.

There are two types of CRPS:

  • Type 1: Without nerve injury (most patients are diagnosed with this type)
  • Type 2: With nerve injury (formerly known as causalgia). This type of CRPS tends to be more painful and is characterized by burning pain.


The pain associated with complex regional pain syndrome is often more severe than the initial injury. Symptoms can start as mild or moderate and get worse over time. Depending on the person, the symptoms may progress either gradually or quickly. 

The first signs of CRPS are usually pain in the affected arm or leg, redness, swelling, and sensitivity to touch and cold.

Other symptoms of complex regional pain syndrome include:

  • Burning or throbbing pain in the limbs
  • Changes in skin temperature, alternating between sweat and cold
  • Changes in skin texture (shiny or dry) and/or color (white, blotchy, red or blue)
  • Stiffness in the joints
  • Muscle spasms, weakness, and muscle loss
  • Loss of movement in the affected arm or leg

Symptoms may last for a few months to several years – and they can get progressively worse.


The doctor will diagnose CRPS based on a physical exam and medical history. The following tests and procedures may also be used to help make a CRPS diagnosis: 

  • Bone scan to help detect changes in bone density
  • X-ray to check for loss of minerals in the bones
  • Magnetic resonance imaging (MRI) to identify tissue changes
  •  Thermography to measure skin temperature and blood flow
  •  Other sympathetic nervous system tests

It is possible to recover fully from CRPS if the treatment starts early, just within months of the first symptoms.

Treatment options may include:

  • Pain relievers (over-the-counter and/or opioids)
  • Topical analgesics
  • Physical therapy
  • Spinal cord stimulation
  • Sympathetic block/ Stellate ganglion block
  • Intrathecal drug pumps
  • Transcutaneous electrical nerve stimulation
  • Other medication (corticosteroids, alpha-blocking drugs, calcium channel blockers)