Complex regional pain syndrome has been known as causalgia and reflex sympathetic dystrophy in the past. Previously, the way this syndrome was diagnosed was not standardised and more derived from the doctors’ personal experience rather than via something more evidence based. The International Association for the Study of Pain (IASP) finally came up with a new name and criteria in 1994, although there was resistance to a “tighter” definition by personal injury lawyers and other patient advocacy groups.
The IASP finally met up again in the fall of 2003 and came up with the following criteria, which is still relevant over 18 years later.
Other than the sensation of pain, and changes in movement and strength, and colour, temperature and swelling, I must emphasise that the pain needs to be out of proportion to the trauma or inciting event like a surgery. Having pain 2 weeks after an ankle surgery may not be CRPS as the magnitude of the surgery and the disruption of the tissues can account for the pain. Having the same pain at 6 months when there is an infection also means that we can’t call it CRPS as there is a cause of the pain (i.e. the ongoing infection). If the tissues have healed but there is still pain that fulfils the criteria below, then perhaps it may be CRPS if there is no other reason that can explain the pain.
Oftentimes there are the signs and symptoms listed below but there is an underlying cause like inflammation of a tendon or joint that is responsible for the pain, which means that the term CRPS may not be applied even though there might be signs of neuropathy and increased sensitivity.
Clinical diagnostic criteria for CRPS
|General definition of the syndrome:|
|CRPS describes 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 of abnormal sensory, motor, sudomotor, vasomotor, and/or trophic findings. The syndrome shows variable progression over time|
|To make the clinical diagnosis, the following criteria must be met:|
|1. Continuing pain, which is disproportionate to any inciting event|
|2. Must report at least one symptom in three of the four following categories:|
|Sensory: Reports of hyperesthesia and/or allodynia|
|Vasomotor: Reports of temperature asymmetry and/or skin color changes and/or skin color asymmetry|
|Sudomotor/Edema: Reports of edema and/or sweating changes and/or sweating asymmetry|
|Motor/Trophic: Reports of decreased range of motion and/or motor dysfunction (weakness, tremor, dystonia) and/or trophic changes (hair, nail, skin)|
|3. Must display at least one sign at time of evaluation in two or more of the following categories:|
|Sensory: Evidence of hyperalgesia (to pinprick) and/or allodynia (to light touch and/or temperature sensation and/or deep somatic pressure and/or joint movement)|
|Vasomotor: Evidence of temperature asymmetry (>1°C) and/or skin color changes and/or asymmetry|
|Sudomotor/Edema: Evidence of edema and/or sweating changes and/or sweating asymmetry|
|Motor/Trophic: Evidence of decreased range of motion and/or motor dysfunction (weakness, tremor, dystonia) and/or trophic changes (hair, nail, skin)|
|4. There is no other diagnosis that better explains the signs and symptoms|