What Causes Complex Regional Pain (CRPS) Syndrome?

Reviewed on 10/8/2020
Pain usually starts in the arm or leg and may spread to other body parts.
CRPS pain usually starts in the arm or leg and may spread to other body parts.

The exact cause of complex regional pain syndrome (CRPS) is not completely understood. Researchers believe that it may be caused by an injury or abnormality of the nervous system. CRPS usually presents after a trauma, infections, a major surgery, a stroke, or a heart attack. The mechanism of why these trigger CRPS is not understood. It could be due to a dysfunction of the interaction between the central and peripheral nervous systems, resulting in inappropriate inflammatory responses.

There are two types of CRPS, and they have different causes but present with similar signs and symptoms:

  • Type 1 CRPS: This is also called reflex sympathetic dystrophy (RSD). It typically occurs after a major illness or an injury. There is no direct damage to the nerves in the affected limb. Type 1 is more common, and about 90% of people with CRPS have type 1 CRPS.
  • Type 2 CRPS: It is sometimes called causalgia. It usually occurs after a nerve injury.

What is complex regional pain (CRPS) syndrome?

Complex regional pain syndrome (CRPS), also called reflex sympathetic dystrophy (RSD), describes a group of painful conditions that are characterized by long-standing, continuous regional pain.

Pain usually starts in the arm or leg and may spread to other body parts. This pain is continuous and intense that is out of proportion to the injury. Other symptoms may include color and temperature changes of the skin over the affected area, skin sensitivity, sweating, and swelling. Those affected may have severe pain, swelling of the limbs, and reduced movements of the affected body parts. About 35% of the affected people report symptoms throughout their whole body. 

CRPS is rare, and the exact cause is unknown. CRPS usually presents after an injury, a major surgery, a stroke, or a heart attack.

What are the signs and symptoms of complex regional pain syndrome?

The signs and symptoms usually begin in one limb initially and eventually spread to the rest of the body. 35% of people with complex regional pain syndrome (CRPS) have symptoms throughout the body. Some of the changes are irreversible, whereas other symptoms may last for months or years. Signs and symptoms of CRPS include:

  • Constant throbbing pain or burning pain, usually in the arm, leg, hand, or foot
  • Increased sensitivity to cold or touch
  • Swelling of the affected area 
  • Changes in skin color, ranging from white to red or blue
  • Changes in skin texture, thinning or shiny appearance in the affected area
  • Frequent changes in the skin temperature, alternating between sweaty and cold
  • Muscle spasms and tremors
  • Weakness and atrophy (muscle loss)
  • Changes in hair and nail growth
  • Joint stiffness and joint damage
  • Limited range of movement
  • Affected limb may become cold and pale

What are the complications of complex regional pain syndrome?

If the complications of complex regional pain syndrome (CRPS) isn't diagnosed and treated early, the disease progresses, becomes debilitating, and leads to irreversible complications. These may include:

  • Atrophy (tissue wasting): CRPS can cause the muscles, bones, and skin to weaken and deteriorate causing difficulty in moving the affected area.
  • Contracture (muscle tightening): Patients experience contracture (tightening) of the muscles, leading the hands, fingers, feet, or toes to contract and remain in a fixed position.
  • Muscle weakness: This is experienced in the affected areas.

Can complex regional pain syndrome be prevented?

These following might help you reduce the risk of complex regional pain syndrome (CRPS):

  • Taking vitamin C after a fractureStudies have shown that consuming high doses of vitamin C after a fracture, especially wrist fracture, may reduce the risk of CRPS.
  • Early mobilization after a strokeResearch has suggested that people who are mobilized by being made to walk soon after a stroke may reduce the risk of CRPS.
  • Timely rehabilitation or physiotherapy: This may help to reduce the risk of CRPS after fractures or injuries.


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