Complex regional pain syndrome (CRPS)

CRPS is a clinical diagnosis made with the Budapest criteria. Treatment centers on graded functional restoration; drugs, sympathetic blocks, ketamine and neuromodulation support rehabilitation rather than replace it.

1. Diagnose with the Budapest clinical criteria. Continuing pain disproportionate to the inciting event, at least one symptom in three of four categories (sensory, vasomotor, sudomotor/edema, motor/trophic), at least one sign in two or more categories, and no better explanation. Imaging and blocks are not required for the diagnosis ¹.
2. Functional restoration is the core. The 5th-edition guidelines center care on graded physical and occupational therapy. Sympathetic blocks, drugs and psychotherapy are used mainly when progress stalls or pain blocks engagement ².
3. Bisphosphonates: modest and short-lived. A 2026 meta-analysis found that bisphosphonates may reduce pain at 1 to 3 months (about 10 points on a 100-point scale, low certainty), with little or no medium-term difference and more adverse events ³.
4. Ketamine infusions have moderate support. The chronic pain ketamine consensus found moderate evidence for CRPS, with improvement lasting up to 12 weeks; avoid it in poorly controlled cardiovascular disease or psychosis and severe hepatic impairment ⁴.
5. DRG stimulation for focal lower-limb CRPS. In ACCURATE, 81.2% treatment success with dorsal root ganglion stimulation versus 55.7% with tonic spinal cord stimulation at 3 months, with more targeted coverage ⁵.
6. Children: exercise therapy plus psychology. Exercise and physical therapy are the cornerstones of pediatric CRPS, within an interdisciplinary program with CBT; invasive treatments have only weak evidence ⁶².

Immobilization perpetuates CRPS: casting healthy volunteers for 28 days produced CRPS-like signs, so rest and disuse should be reversed, not prescribed ².

• Budapest clinical criteria kept the IASP criteria's sensitivity (0.99) and improved specificity (0.68); the research criteria are more specific (0.79) ¹.
• Signs must be observed on examination in at least two categories ¹.
• Graded motor imagery has mixed trial results; functional restoration is the consistent core ².
• Bisphosphonates probably increase adverse events (risk ratio 1.1, moderate certainty) ³.
• ACCURATE enrolled lower-extremity CRPS only, so it does not support upper-limb DRG use ⁵.
• In children, PT plus CBT improved pain and function in a randomized trial, with sustained benefit in most ².

• Waiting for pain to settle before starting graded therapy ².
• Requiring imaging or a sympathetic block response to make the diagnosis; Budapest criteria are clinical ¹.
• Calling bisphosphonates a cure or durable treatment ³.
• Offering a sympathetic block or a stimulator trial in place of rehabilitation rather than to enable it ².