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Complex regional pain syndrome

Evidence: Unconfirmed

Names

Amplified musculoskeletal pain syndrome
Causalgia
Complex Regional Pain Syndrome
Reflex Sympathetic Dystrophy

Description

Complex regional pain syndrome (CRPS) and amplified musculoskeletal pain syndromes (AMPS) are chronic pain conditions lasting at least 6 months. CRPS is often triggered by an injury followed by immobilization, and is marked by pain that does not diminish in a manner typical for the injury.  Patients experience unreasonably intense pain in the arms, legs, hands, or feet, both in response to painful and non-painful triggers. Pain can include burning, tingling, or squeezing sensations.  Redness and swelling are often present in the affected area. 

There are two types of CRPS.  Patients with CRPS-I/Reflex Sympathetic Dystrophy do not have a confirmed nerve injury, whereas patients with CRPS-II/Causalgia do have an associated, confirmed nerve injury. CRPS usually occurs after an injury that caused damage to the nervous system.

The cause is unknown but there are correlations with immune processes that result in swelling surrounding injury.  Treatments are available to manage symptoms, which help some patients, but not all.  Younger patients are more likely to recover than older patients, whose pain may persist and lead to disability.

There is no known cause, and autoimmunity is suspected, but no evidence of autoimmunity has been definitively linked to CRPS.

Prevalence

US Cases: 65,000 [Sandroni 2003]

Typical Age of onset

50-70 years of age
Source: Guthmiller and Varacallo (2019) 

Symptoms

  • Chronic pain in the limbs

  • Initial redness and swelling of the affected area followed by coolness and blue coloring

  • Thin, shiny skin over the affected area

  • Changes in nail and hair growth patterns on the affected limb

  • Stiffness in the affected joints/limbs

  • Decreased mobility or coordination in affected limb

  • Tremors or involuntary spasms (dystonia)