As it stands, there is currently no single test (a clinical diagnosis based entirely upon a set of accepted guidelines) that can definitively diagnose CRPS.
In 2004, a conference held in Budapest by the International Association for the Study of Pain (IASP) adopted a new set of guidelines which replaced the older ones introduced in the previous decade. These guidelines were named the Budapest Criteria.
The Budapest Criteria differentiates between ‘signs’ and ‘symptoms’. The ‘signs’ are seen or felt by the person carrying out the examination, and the ‘symptoms’ are what is reported by the patient to the doctor. A common problem with diagnosing CRPS is that sometimes, not all signs or symptoms are presenting at the same time as the examination.
To receive a diagnosis under the Budapest Criteria, a person must have at least one symptom in three of the four following categories:
- Sensory – Hyperaesthesia (an abnormal increase in sensitivity), and/or allodynia, which is pain caused by stimuli which shouldn’t trigger a painful response. Examples of allodynia include lightly touching the affected limb, perhaps by moving a bedsheet or by a gentle tap on the wrist.
- Vasomotor – Skin colour changes and/or changes in temperature of the limb.
- Sudomotor/oedema – Swelling of the limb and/or an excess of sweat from the affected limb, or changes in sweating swelling of the limb.
- Motor/Trophic – Decreased range of motion and/or motor dysfunction, including weakness, spasms, tremors or wasting. Trophic changes include changes to the hair, nails or skin on the affected limb.
At the time of clinical examination, at least one sign must be present to the person carrying out the examination in two or more of the categories listed below, they vary slightly to the list above.
- Sensory – Hyperalgesia (to pinprick), a heightened sensitivity to pain, and/or allodynia to light touch or deep somatic (physical) pressure and/or joint movement
- Vasomotor: temperature differences between the limb, and/or skin colour changes and/or skin colour changes between the limb
- Sudomotor/oedema: oedema and/or sweating changes and/or sweating differences between the limbs.
- Motor/trophic: decreased range of motion and/or motor dysfunction (ie weakness, tremor or muscle spasm) and/or trophic changes (hair and/or nail and/or skin changes).