Complex Regional Pain Syndrome


Complex Regional Pain Syndrome typically presents as persistent and often severe pain in one arm or leg. The instigating factor is an injury to the arm or the leg. However, the reaction is magnified, and the pain can occur throughout the limb even if the injury is more localized. CRPS is classified as one of two types:

Type 1: Occurs after a fracture or sprain and does not involve nerve damage. It is also referred to as Reflex Sympathetic Dystrophy (RSD)

Type 2: Follows nerve damage to a limb and is also labeled as causalgia


There are multiple factors that can contribute to the development of complex regional pain syndrome. Immobilization is associated with CRPS type 1. Immobilizing limbs after fractures and surgery can increase sensitivity to pain, cause swelling and fluid build-up (edema), and increased temperature of the affected limb.

Changes in the nervous system can contribute to CRPS. The “fight or flight” portion of the nervous system, known as the sympathetic nervous system, is activated by very high stress levels. This leads to constriction of blood vessels, which reduces blood flow to the extremities. Sympathetic nervous activity may initially be decreased in CRPS, which may explain the red, warm and swollen arm or leg.

Inflammation is thought to play a role in complex regional pain syndrome. In the early stages of CRPS, patients have high levels of cytokines, which cause inflammation. There are other pain mediators present that amplify the perception of pain. The cytokines and pain mediators cause an exaggerated pain response to a stimulus that should cause little to no pain.

Genetic risk factors are hypothesized to contribute to the development of complex regional pain syndrome. However, there is no clear evidence of this yet.

Anxiety, depression, and anger can exacerbate the symptoms of CRPS.


  • Pain felt deep inside the affected limb with burning and stinging

  • Sensory changes with increased sensitivity to pain and occasionally, sensory loss

  • The affected extremity is often warm, red, and swollen but can change over time to feeling cool with dark or bluish skin

  • Fluid build up in the affected extremity, known as edema

  • Swelling

  • The skin of the affected limb may become shiny and thin

  • There may be increased or decreased hair and nail growth in the affected extremity

  • Weakness of the affected extremity with a diminished range of motion

  • Spasms can occur as well as involuntary muscle contractions


The patient history and physical exam are used to make a diagnosis of complex regional pain syndrome. There is no standard diagnostic study. Commonly used criteria for the diagnosis of CRPS include those published by the IASP (International Association for the Study of Pain). These are based on patient-reported signs and symptoms and on the physical presentation of the patient.


Complex regional pain syndrome is managed through a multispecialty approach that includes various types of therapy, medications, therapeutic modalities, and procedures. Physical therapy is very important and should be initiated early. The goal is diminished pain and keeping the limb active and moving. This promotes circulation and prevents loss of muscle tone and stiffness.

An occupational therapist can teach you several techniques that can help you cope with the pain of CRPS. These include desensitization which aims to normalize touch sensations to the affected arm or leg. Relaxation and body perception awareness training can help as well.

Psychologists also play an important role in helping CRPS patients deal with the mood-altering effects of chronic pain. They can help with stress management and cognitive behavioral therapies.

Medications used to treat complex regional pain syndrome include anticonvulsants, which diminish pain signal transmission from nerves to the brain. Tricyclic antidepressants also work in a similar manner to reduce the pain of CRPS. Other pharmacologic therapies include the fentanyl patch, oral opioids, and nonsteroidal anti-inflammatory drugs.

Trans-cutaneous electrical nerve stimulation may help as well. It involves transmitting a mild current through electrodes placed on the skin in order to disrupt pain signals to the brain.

An interventional pain management physician can perform specialized blocks using targeting injections of local anesthetics near nerve bundles. These procedures aim to block pain signals to the brain as well and may provide relief from the pain of CRPS.

Spinal cord stimulation involves implanting a thin wire in the epidural space in close proximity to spinal nerves. The wire connects to an external unit used to control mild electrical impulses that interrupt pain transmission to the brain. If the stimulation works in diminishing the pain, the battery unit can be surgically implanted. The wire and battery can be removed if the spinal cord stimulation is no longer needed.