Complex regional pain syndrome (CRPS) is characterised by chronic and often debilitating pain, usually in a limb. It has had many synonyms, including shoulder-hand syndrome, causalgia and Sudeck's atrophy.
There are two types of CRPS, depending on whether there is identifiable major nerve injury (type 2) or not (type 1). In general, this distinction does not affect management, but it is important to identify the mechanism of nerve injury in type 2.
Typically, CRPS follows injury or surgery. In 9% of cases, there is no identifiable inciting event and in others, the injury is minor or trivial. The incidence is about 26 per 100,000 person-years, but transient forms may occur in a quarter of all injuries, often remaining unrecognised.
Diagnosis can be difficult because the average GP sees it infrequently and the symptoms can be puzzling, especially in the early stages.
The pain is often described as burning and is typically out of proportion to the insult. There may be limb dysfunction (including clumsiness or disuse) and psychological distress, leading the clinician to suspect underlying mental health problems.
Patients sometimes describe feeling as though the limb is not theirs or is alien - this is different from some stroke syndromes because in CRPS, patients accept the limb as theirs.
Diagnosis is made using the Budapest criteria (see box above) and depends on sensory, vasomotor, sudomotor (sweating) and motor signs and symptoms.
There is no link between CRPS and pre-existing psychological problems, somatisation or 'malingering'. However, patients may require psychological support to deal with the problems caused by chronic pain, sleep disturbance and inability to work.
Be alert for the usual 'yellow flags' (excessive illness behaviour, poor coping strategies), which might indicate a poorer outcome and prompt early referral to specialist services.
Explain that the cause of CRPS is unknown and there is no cure. If it follows surgery, this does not imply the surgery was carried out negligently.
If you suspect peripheral nerve injury following surgery or trauma, the patient should be referred urgently. Written information may be helpful for the patient.
The mainstay of treatment is physiotherapy, which aims to avoid secondary problems associated with disuse of the affected limb. Refer all but the mildest cases urgently.
Initial therapy will focus on mobilisation and strengthening exercises, and desensitisation.
Many patients with CRPS will also need referral to specialist services for confirmation of diagnosis, pain control or rehabilitation.
Pain control can be difficult. Prescribe analgesics in accordance with the WHO analgesic ladder, but avoid strong opiates except on specialist advice. Consider starting medication for neuropathic pain after three weeks (or earlier) if pain remains uncontrolled. NSAIDs may be helpful where there is soft tissue injury.
Monitor the patient's mood and sleep, and offer interventions where appropriate.
About 15% of patients experience unrelenting pain and impairment five years after onset. The use of self-help, peer support groups and exercises may help to maintain independence and levels of activity. Do not forget that family and friends may also need advice and support. Some patients still report feeling stigmatised by healthcare professionals who do not believe that their condition is real.
- Dr Martin is a GP in Oldham and EKU author for the RCGP
- RCGP Essential Knowledge Update 10. www.elearning.rcgp.org.uk
- Goebel A, Barker CH, Turner-Stokes L et al. Complex regional pain syndrome in adults: UK guidelines for diagnosis, referral and management in primary and secondary care. London, RCP, 2012.
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