Complex regional pain syndrome

Pain medicine consultant Dr Andreas Goebel on spotting and managing CRPS

Complex regional pain syndrome – formerly called reflex sympathetic dystrophy, causalgia or Sudeck's atrophy – is a painful condition that usually develops after trauma to a limb. Patients report sensory, autonomic, motor and skin changes, but the lead symptom is pain.

CRPS is relatively uncommon with a prevalence of about 1:2,000 and can mimic other limb conditions, so unfortunately is often diagnosed late. The case study below is a typical example.

This woman's symptoms raise a wide differential diagnosis, but few of us would usually consider CRPS.

CRPS is a diagnosis of exclusion and the diagnostic criteria have recently been updated as the Budapest Criteria (see box).

Around 85% of patients will get better within the first 12 to 24 months. Later improvement is also possible but some may have this condition for years. Even where the pain eventually improves, residual limb dysfunction prevents most people from going back to their jobs – in fact even after six years, only 30% do.

The CRPS aetiology is not well understood. It is associated with osteoporosis, migraine, asthma and ACE-inhibitor use but not with preceding psychological problems.1 Certain unusual features, such as a fluctuating inability to move the affected hand or foot, have led to suggestions it is due to somatisation.

Also, many patients feel estranged from their limb and may even express a wish to have it amputated.2 We now know these features are related to dramatic changes in the cortical representation of the affected limb, the so-called Penfield homunculus. CRPS can affect people from all walks of life, but it is more common in women and less common in children and adolescents. The foremost challenge for most doctors, including GPs, is to recognise the condition.

Diagnosis

A presentation of ongoing unilateral limb pain after trauma should alert GPs to CRPS as a possible diagnosis. But 10% of patients report no or only trivial trauma. Bilateral onset is possible and in 7% of cases the condition can spread to other limbs.

The autonomic features of the condition may give it away. The painful limb is often swollen and becomes red or mottled-blue – sometimes white – and can become cold or warm.

Sometimes the affected limb can profusely sweat and hair and nail growth can be altered. As CRPS becomes long-standing – longer than a year – some of these features may disappear, although the pain can remain, making diagnosis even more of a challenge. Many patients may also have allodynia.

Referral and management

Suspected CRPS should be referred to a pain clinic, except in cases with only mild pain, little distress, and where symptoms seem to be resolving. The pain specialist will probably first arrange for specialised physiotherapy or occupational therapy, including mirror therapy, which requires the patient to hide the affected limb behind a mirror, positioned perpendicular to the midline of the body.

When looking into the mirror and performing bilateral synchronised gentle movements, the virtual affected limb – the reflection of the unaffected limb – looks normal and moves normally. This treatment can be very effective, although it is not known exactly how it works.

The specialist is also likely initiate standard neuropathic medication although ideally this would be started by the GP while the patient waits for referral.3

Unfortunately, despite medication for neuropathy, many patients will become progressively frustrated and depressed. It can be appropriate to refer them to a multidisciplinary pain-management programme – usually involving cognitive behaviour therapy.4 Although pain intensity won't necessarily change, patients often find these programmes help them manage better.

Finally, stimulator treatment of the spinal cord – where an epidural catheter is electrically stimulated by an implanted battery – helps around half of patients.

It is the only NICE-approved treatment for CRPS.5 It is not a cure and many patients still struggle to come to terms with the condition despite getting pain relief.

Many patients get better either spontaneously or with specialist input but CRPS will often become a long-term condition. Best management is poorly defined and more work is needed to find out how we can best support our patients. It is important the patient feels listened to, even though there may be little therapeutically that can be offered in refractory CRPS.

Guidelines and support for GPs

A CRPS guideline development process has been started, with the support of the RCGP, and other royal colleges and professional organisations. It will become available in spring 2011. Some GP record systems offer a CRPS template (EMIS PCS, LV and EMIS web). You should also note that there are now updated Read Codes for CRPS.

Dr Andreas Goebel is senior lecturer and honorary consultant in pain medicine at Liverpool University and The Walton Centre NHS Trust

Dr Goebel's work has been supported by the Pain Relief Foundation, Liverpool. The author would like to thank Dr Chris Barker for his help with this article

Competing interests None

A 34-year-old lady noticed a painful blister under her left foot shortly after she had completed a half-marathon run. Within 24 hours the whole foot became swollen, red and extremely painful. She went to A&E, where X-rays and bloods, including inflammatory markers, were normal. Intravenous morphine relieved the pain by 40%, but made her nauseous. She was sent home and was advised to put her leg up and apply ice. Seven days later her symptoms had not improved.

All of the following statements must be met:
• the patient has continuing pain which is disproportionate to the inciting event
• the patient has at least one sign in two or more of the categories below
• the patient reports at least one symptom in three or more of the categories below
• no other diagnosis can better explain the signs and symptoms.