- 1. Complex regional pain syndrome (CRPS) is a syndrome typically occurring in a single extremity following trauma and is characterized by allodynia, hyperalgesia, and vasomotor signs.
- 2. A characteristic three-phase bone scan (TPBS) has moderate sensitivity (50%–80%) but high specificity for the diagnosis of CRPS and predicts a better response to corticosteroid therapy.
- 3. A spinal cord stimulator reduces pain approximately 50% in 50% of patients with severe CRPS.
CRPS is defined as “an array of painful conditions that are characterized by a continuing (spontaneous and/or evoked) regional pain that is seemingly disproportionate in time or degree to the usual course of any known trauma or other lesion. The pain is regional (not in a specific nerve territory or dermatome) and usually has a distal predominance (never head or trunk) of abnormal sensory, motor, sudomotor, vasomotor, and/or trophic findings. The syndrome shows variable progression over time.”
There are two types:
- CRPS type I (formerly reflex sympathetic dystrophy) (90% of all CRPS): cases that occur without evidence of a peripheral nerve injury.
- CRPS type II (formerly causalgia) (10% of all CRPS): cases that occur with a peripheral nerve injury.