Complex regional pain syndrome

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  • CRPS

Other Names

  • Reflex sympathetic dystrophy (RSD)
  • Causalgia
  • Reflex neurovascular dystrophy (RND)
  • Amplified musculoskeletal pain syndrome (AMPS)


  • Disorder of the extremities characterized by regional pain that is disproportionate in time or degree to the usual course of any known trauma or other lesion
  • Pain is not in a specific nerve territory or dermatome
  • Pain usually has a distal predominance of abnormal sensory, motor, sudomotor, vasomotor, and/or trophic findings
  • CRPS often worsens over time
  • 35% of patients report symptoms throughout their whole body.[1]


Type I NO evidence of peripheral nerve injury (edema, erythema, numbness), 90% of clinical presentations
Type II YES evidence of peripheral nerve injury, considered more serve type


  • Generally unknown
  • Inciting event
    • Found in about 90% of cases - usually begin 4-6wks after fractures, crush injuries, sprains, and surgery.[2]
  • Proposed mechanisms
    • Classic inflammation, neurogenic inflammation, and maladaptive changes in pain perception at the level of the central nervous system

Clinical Features

Type II CRPS showing skin changes[3]
Pain burning, stinging, or tearing sensation that is felt deep inside the limb, usually continuous but can be paroxysmal.[4]
Sensory hyperalgesia, allodynia, or hypesthesia
Motor weakness, occasional tremor, myoclonus, or dystonic postures
Skin warmth, skin color changes, sweating, or edema, other skin/hair/nail changes

Differential Diagnosis


Clinical: Budapest consensus criteria:

At least 1 symptom in three of the following four categories:

Sensory allodynia, hyperalgesia
Vasomotor temperature asymmetry, skin color changes, skin color asymmetry
Sudomotor edema, sweating
Motor/trophic decreased ROM, weakness, tremor, dystonia, trophic changes (hair, nail, skin)
And, there is no other diagnosis that better explains the signs and symptoms

Rule-Out Emergent Etiologies

Other Imaging

  • CT/MRI/XR are all NOT diagnostic for CRPS[4]


Ketamine for Flare-Ups

  • Initial bolus - 0.2–0.3 mg/kg of infused over 10mins.[3]
    • Avoid IV push - could cause dissociative side effects.
    • Diagnostic- pain should resolve by the end of the 10min bolus and if so, continue
  • Infusion - 0.2 mg/kg/hr over 4-6hrs.

No discharge prescription usually required. If needed:

Opioids should NOT be used for chronic or acute CRPS. Patient education on this is important.


  • Outpatient follow-up with pain management
  • Referral for PT/OT - important for all CRPS patients
  • Consider psychiatric referral if warranted

See Also

Acute pain management

External Links


  1. Schwartzman RJ, Erwin KL, Alexander GM (May 2009). "The natural history of complex regional pain syndrome". The Clinical Journal of Pain. 25 (4): 273–80. doi:10.1097/AJP.0b013e31818ecea5. PMID 19590474.
  2. Sandroni P, Benrud-Larson LM, McClelland RL, Low PA. Complex regional pain syndrome type I: incidence and prevalence in Olmsted county, a population-based study. Pain 2003; 103:199.
  3. 3.0 3.1 Ducharme, Jim, MD. "Tips for Managing Complex Regional Pain Syndrome - ACEP Now." ACEP Now. N.p., 11 Sept. 2015.
  4. 4.0 4.1 4.2 Birklein F, O'Neill D, Schlereth T. Complex regional pain syndrome: An optimistic perspective. Neurology 2015; 84:89.
  5. Harden RN, Oaklander AL, Burton AW, et al. Complex regional pain syndrome: practical diagnostic and treatment guidelines, 4th edition. Pain Med 2013; 14:180.