Reflex sympathetic dystrophy

Complex regional pain syndrome (CRPS) is also known as Sudek's atrophy and reflex sympathetic dystrophy (RSD). It describes the presence of regional pain after a harmful event. The symptoms and signs - usually in the limbs - are excessively severe and inappropriately prolonged given the magnitude of the original injury. Autonomic, sensory and motor features may be present.

Complex regional pain syndrome is a chronic pain condition characterized by autonomic and inflammatory features.

• occurs acutely in about 7% of patients who have limb fractures, limb surgery, or other injuries
• often will resolve within the first year - a smaller subset of patients progress to the chronic form
  • the transition from acute to chronic form is often paralleled by a change from "warm complex regional pain syndrome," with inflammatory characteristics dominant, to "cold complex regional pain syndrome" in which autonomic features dominate
• multiple peripheral and central mechanisms seem to be involved
  • possible contributors include peripheral and central sensitization, autonomic changes and sympatho-afferent coupling, inflammatory and immune alterations, brain changes, and genetic and psychological factors

It is a major cause of disability with only one in five sufferers able to fully resume prior activities. The earlier a diagnosis is made and treatment is commenced, the better the prognosis.

Effective management of chronic form of this condition is often challenging.

Reference:

• Bruehl S. Complex regional pain syndrome. BMJ. 2015 Jul 29;351:h2730.