What is CRPS?

When it comes to defining complex regional pain syndrome (CRPS) it can be useful to head to the clinical guidelines in the first instance. CRPS is a complex condition that has been around for generations, initially named Causalgia during the Civil war and has been renamed many times since then. CRPS has been known as various conditions including: Sudecks atrophy, Reflex Sympathetic Dsytrophy (RSD – and you will come across it still called this in many overseas areas), Reflex neurovascular dystrophy (especially in children), eventuating with the most current descriptor, CRPS.

There are no tests that can be carried out to definitively diagnose CRPS, therefore this condition is essentially a clinical diagnosis based on the most current guidelines. Nor will you always see clear visible signs pointing straight to CRPS as the reason for the symptoms the patient is experiencing. This can often cause some question into whether the diagnosis is CRPS and can mean the patient may suffer unnecessarily due to lack of treatment – invisible illness strikes again.

There are a number of more common risk factors that may increased your risk of developing CRPS including: trauma (most commonly fractures), immobilisation, and other inciting events such as sprains, soft-tissue injuries, iatrogenic injuries from phlebotomy or injections, stroke, myocardial infarction, brain or spinal injury, presence of neoplasia, pregnancy, or varicella zoster virus infection. This is not an exhaustive list and you may have gone on to develop CRPS from some other event or illness.

Current guidelines for diagnosing CRPS are as follows:

(Diagnostic criteria proposed by the international consensus conference, Budapest, 2004)

CRPS is defined as continuing pain disproportionate to any inciting event. A patient must have at least 1 symptom in 3 of the 4 following categories

  • Sensory: hyperaesthesia and/or allodynia.
  • Vasomotor: temperature asymmetry and/or skin colour changes and/or skin colour asymmetry.
  • Sudomotor/oedema: oedema and/or sweating changes and/or sweating asymmetry.
  • Motor/trophic: decreased range of motion and/or motor dysfunction (weakness, tremor, dystonia) and/or trophic changes (hair, nail, skin).

At least 1 sign must be present at the time of evaluation in 2 or more of the following categories.

  • Sensory: hyperalgesia (to pinprick) and/or allodynia (to light touch and/or deep somatic pressure and/or joint movement).
  • Vasomotor: temperature asymmetry and/or skin colour changes and/or asymmetry.
  • Sudomotor/oedema: oedema and/or sweating changes and/or sweating asymmetry.
  • Motor/trophic: decreased range of motion and/or motor dysfunction (weakness, tremor, dystonia) and/or trophic changes (hair, nail, skin).

No other diagnosis can explain the signs and symptoms.

The International Association for the Study of Pain (IASP) has now approved the Budapest criteria as the new diagnostic criteria for CRPS. The Budapest criteria now supersede the diagnostic criteria published by the IASP in 1994.

IASP went further and defined two types of CRPS, the difference between type 1 and type 2 being an identifiable nerve injury preceding symptoms for type 2.

You may come across talk of ‘hot’ or ‘cold’ CRPS; there is no scientific data to back this up at this point, nor is it usual to describe CRPS in ‘stages’ anymore as an individuals presentation of CRPS is unlikely to fit neatly in any ‘stage’ box. CRPS is difficult enough to understand without making it even more complex.

The incidence rate of CRPS in New Zealand is currently unknown but this is a worldwide. It is difficult to quantify numbers as management of CRPS crosses over many specialties, incidence as reported in overseas studies differ from 5.46 per 100,000 person-years to 26.2 per 100,000 person-years. Also, due to the lack of knowledge around CRPS, it is suspected there are still a number of people who do not end up with a diagnosis.