John Bonica was instrumental in the foundation of the International Association for the Study of Pain (IASP) in 1973 after inviting delegates to an International Symposium on Pain. He also made sure that it was multidisciplinary, with all professionals interested in reducing pain and suffering invited to participate on an equal basis.10
To create diagnosis criteria for reflex sympathetic dystrophy a consensus conference was organized by the IASP in 1988 at Schloss Rettershof, near Frankfurt, and a second one in Orlando, Florida in 1993.
Bonica proposed to rename the disease as ‘Complex Regional Pain Syndrome’ (CRPS)’.
The name was changed to Complex Regional Pain Syndrome in 1994 and the Orlando Conference established that CRPS could be diagnosed in presence of the following conditions:6
The presence of an initiating noxious event or a cause of immobilization.
Continuing pain, allodynia, or hyperalgesia with which the pain is disproportionate to any inciting event.
Evidence at some time of oedema, changes in skin blood flow, or abnormal sudomotor activity in the region of pain.
This diagnosis is excluded by the existence of conditions that would otherwise account for the degree of pain and dysfunction.
According to IASP, CRPS is a syndrome characterized by a continuing (spontaneous and/or evoked) regional pain that is seemingly disproportionate in time or degree to the usual course of pain after 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 oedema, and/or trophic findings. The syndrome shows variable progression over time.
In the same conference in Orlando it was decided to differentiate between the form characterized by the evidence of obvious nerve damage (CRPS type II, corresponding to causalgia) and the form without demonstrable nerve lesions (CRPS type I).1
The Orlando criteria resulted in a large number of misdiagnosed patients. Stephen Bruehl and Norman Harden, both Pain Medicine specialists and members of the IASP Task Force on CRPS published two articles about a study carried out to test the internal and external validity of the Orlando criteria in 1999. The results of the study led to a proposal of a substantial revision of the Orlando criteria. The main change proposed by Harden et al. was to add clinical signs.1
Following this in 2003 in Budapest a further consensus conference put forward a new classification system. It proposed the presence of at least two clinical signs included in the four categories and at least three symptoms in its four categories.
The Budapest Criteria forms the basis of the diagnostic criteria still in use today.
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 hyperalgesia and/or allodynia.
Vasomotor: Reports of temperature asymmetry and/or skin colour changes and/or skin colour asymmetry.
Sudomotor/Oedema: Reports of oedema 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, nails, 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 deep somatic pressure and/or joint movement).
Vasomotor: Evidence of temperature asymmetry and/or skin colour changes and/or asymmetry.
Sudomotor/Oedema: Evidence of oedema 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, nails, skin).
4. There is no other diagnosis that better explains the signs and symptoms.
*A sign is counted only if it is observed at time of diagnosis.
**Research criteria for CRPS are recommended that are more specific, but less sensitive than the clinical criteria; they require that four of the symptom categories and at least two sign categories be present.
CRPS I (old name: Reflex Sympathetic Dystrophy): As defined above.
CRPS II (old name: Causalgia): Defined as above with electrodiagnostic or physical evidence of a major nerve lesion.
CRPS-NOS* (Not Otherwise Specified): Partially meets CRPS criteria, not better explained by any other condition.
*This subtype was added to capture any patients previously diagnosed with CRPS who now do not meet criteria as elaborated above.