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Complex regional pain syndrome medicalises limb pain

BMJ 2014; 348 doi: https://doi.org/10.1136/bmj.g2631 (Published 28 April 2014) Cite this as: BMJ 2014;348:g2631

Re: Complex regional pain syndrome medicalises limb pain

Sir,

 

This letter is in response to the personal viewpoint article “Complex regional pain syndrome medicalises limb pain1.

 

Whilst it is to be welcomed that Bass highlights the need for greater psychological input to NHS pain clinics, and the frequent role of psychological factors in the maintenance of chronic pain conditions such as complex regional pain syndrome (CRPS), we are concerned that the article appears to suggest that i) the causation of CRPS is largely within the psychological domain; and moreover that ii) somehow the condition could be minimised or averted if only it could be re-framed in a manner that demedicalised the problem – Bass states “there is a case for abandoning the term CRPS altogether because of its potential for iatrogenic harm” – and indeed he suggests we consider alternative descriptive terms such as “armache or legache”.

 

There is now abundant evidence to implicate autoimmune and oxidative stress processes within the causation of a significant number of CRPS cases2-4 and although not fully understood, it now looks very likely that any consideration of the aetiology of CRPS must largely focus upon neurophysiological and neurochemical pain processing pathways within a complex multifactorial context that also includes genetic and environmental factors. Furthermore, magnetic resonance imaging demonstrates structural abnormalities of connectivity between brain structures in CRPS – measures that are separable5 from those in other chronic pain conditions such as chronic back pain and fibromyalgia.  Clearly the position that CRPS arises because of pre-accident psychological factors or post-accident factors such as the pursuit of litigation are not in concordance with a growing body of evidence relating to the neuropathological aetiology of the condition.  As the UK guidelines on CRPS puts it lucidly, “It is also now clear that CRPS is not associated with a history of pain-preceding psychological problems, or with somatisation or malingering”6. Prospective studies also dismiss any such psychological factors in the genesis of CRPS7.

 

Nonetheless, psychological factors are of considerable importance in the management of CRPS, as with other chronic pain conditions, and the development of distress, helplessness and depression, in addition to dysfunctional pain beliefs and behaviours (for example the belief that the pain is harmful and that avoiding activity will help the recovery, and behaviours of guarding and avoidance of movement) are “Yellow Flags” associated with chronicity in acute back pain8 and which are equally applicable to outcome in CRPS6.  Authors of this letter include a psychiatrist and pain medicine clinician practicing within an NHS pain clinic, in cases where we encounter patients with CRPS in whom significant levels of disability have developed, psychiatric enquiry often reveals the onset of enhanced levels of disability to be chronologically associated with the onset or worsening of depression or some other form of psychological distress such as symptoms of post-traumatic stress disorder (PTSD).  In such cases, appropriate treatment of these psychological exacerbating and maintaining factors is hugely important as part of a multi-disciplinary approach to treating the CRPS9.

 

However, recognition of the underlying CRPS is vital and informs the provision of specialist treatments by Pain Medicine colleagues (in the form of specialist rehabilitation programmes and pharmacological and neuromodulatory interventions where appropriate).  To replace the CRPS diagnosis with a descriptive term such as “disproportionate pain” or “armache” would be a retrograde step, obfuscating that which has been clearly demarcated and elucidated through clinical and basic research.

 

Equally, one cannot ignore the serious impact that Bass’ proposed changes could have upon the assessment of chronic pain conditions in the courts.  Over the years, great strides have been made by the legal profession in recognising the validity of diagnoses in Pain Medicine. This has been reflected by the introduction of a separate section relating to Chronic Pain Disorders, including CRPS, within the 11th and 12th edition Judicial College Guidelines for the Assessment of General Damages in Personal Injury Cases. Judicial findings of CRPS are now commonplace, based on tested expert medical opinion, leading to financial awards that are commensurate with what is often a significant level of disability. Declassifying CRPS would have the potential to undermine the now generally accepted proposition that pain disorders should not be viewed through a prism of psychiatric injury or damage alone and therefore deny those suffering from CRPS a fair level of compensation. This would be a matter of some concern amongst those representing injured parties.

 

Finally, whilst psychological treatments are an essential part of the toolkit in treating CRPS and psychological processes are often key to understanding the perpetuation of chronic presentations, neuropathology and pain mechanisms not psychology are at the heart of causation of CRPS and psychological treatments cannot replace the specialist Pain Medicine rehabilitative, pharmacological and interventional treatments that CRPS patients often require.  To put it another way – just because one of the tools we need is a hammer, doesn't mean that the problem must be a nail.

 

 

References:

 

1. Bass C. Complex regional pain syndrome medicalises limb pain. BMJ 2014;348:g2631.

2. Goebel A, Blaes F. Complex regional pain syndrome, prototype of a novel kind of autoimmune disease. Autoimmunity reviews 2013;12(6):682-6.

3. Tekus V, Hajna Z, Borbely E, et al. A CRPS-IgG-transfer-trauma model reproducing inflammatory and positive sensory signs associated with complex regional pain syndrome. Pain 2014;155(2):299-308.

4. Taha R, Blaise GA. Update on the pathogenesis of complex regional pain syndrome: role of oxidative stress. Canadian journal of anaesthesia = Journal canadien d'anesthesie 2012;59(9):875-81.

5. Geha PY, Baliki MN, Harden RN, et al. The brain in chronic CRPS pain: abnormal gray-white matter interactions in emotional and autonomic regions. Neuron 2008;60(4):570-81.

6. Royal College of Physicians. Complex regional pain syndrome in adults: UK guidelines for diagnosis, referral and management in primary and secondary care. Royal College of Physicians: London, 2012.

7. Beerthuizen A, Stronks DL, Huygen FJ, et al. The association between psychological factors and the development of complex regional pain syndrome type 1 (CRPS1)--a prospective multicenter study. Eur J Pain 2011;15(9):971-5.

8. Main CJ, Williams ACC. Musculoskeletal pain. In: Mayou R, Sharpe M, Carson A, eds. ABC of Psychological Medicine. London: BMJ Publishing Group, 2003:37-40.

9. Harden RN. Complex regional pain syndrome. British Journal of Anaesthesia 2001;87(1):99-106.

 

 

 

Dr Michael D Spencer

Honorary Consultant Psychiatrist, Department of Pain Medicine, West Suffolk Hospital, Bury St Edmunds IP33 2QZ, UK.

 

Mr Stuart McKechnie

Barrister, 9 Gough Square, London EC4A 3DG.

 

Dr Rajesh Munglani

Honorary Consultant in Pain Medicine, Department of Pain Medicine, West Suffolk Hospital, Bury St Edmunds IP33 2QZ, UK.

 

 

Competing interests: No competing interests

04 June 2014
Michael D Spencer
Honorary Consultant Psychiatrist
Stuart McKechnie, Rajesh Munglani
West Suffolk Hospital
Department of Pain Medicine, West Suffolk Hospital, Bury St Edmunds IP33 2QZ, UK