Complex regional pain syndrome - Diagnosis 

There is no single test for complex regional pain syndrome (CRPS). It is usually diagnosed by ruling out other conditions that have similar symptoms.

Tests

Possible tests used to rule out other conditions are:

• blood tests to rule out an underlying infection or rheumatoid arthritis
• a magnetic resonance imaging (MRI) scan to rule out underlying problems with your tissue or bones
• a biopsy, where a small tissue sample is removed and checked for the presence of abnormal cells
• an X-ray to rule out problems with the joints and bones

Tests that give a good indication that you have developed CRPS (although they can't confirm it) are described below.

• A physical examination, where your GP or another specialist will check for physical signs of CRPS, such as swollen joints and changes to your skin’s temperature and appearance.
• Sweat testing, where the sweat produced by both your affected limb and an unaffected limb is measured. A large difference between the two readings could indicate CRPS.
• Thermography, where an infrared thermometer is used to measure your skin temperature at different parts of your body. If your affected limb has a much higher, or lower, skin temperature than the rest of your body, it could indicate CRPS.
• Electrodiagnostic testing, where wires are attached to your skin to measure the electrical activity of your nerves. Abnormal readings may suggest that your nerves are damaged, and that you have type two CRPS.

Diagnostic checklist

As CRPS can be difficult to diagnose, experts have created a checklist to assist GPs and other healthcare professionals when making a diagnosis.

A diagnosis of CRPS can be made if the following signs and symptoms are present:

• You have recently experienced an injury or other type of trauma.
• You have ongoing pain in a limb disproportionate to the original injury or trauma.
• There is physical evidence of swelling, and changes to your skin temperature and appearance.
• No other diagnosis would better explain your signs and symptoms.

Referral

If you are diagnosed with CRPS, you may be urgently referred to a specialist pain clinic. There are around 300 pain clinics in the UK, mostly within hospitals.

There is also a national centre for CRPS based at the Royal National Hospital for Rheumatic Diseases in Bath. You may be advised to visit the centre once your diagnosis is confirmed so that a treatment plan can be drawn up.

An urgent referral ensures treatment can be started immediately, because the earlier treatment is started, the less likely it is that you'll have any long-term disability.