INTRODUCTION
At the same time as the study of pain is flourishing as a basic and applied science, and attention is paid nationally to reducing the gap between provision and need (chronic/persistent pain is a Royal College of General Practitioners priority for 2011-2013),1,2 there are moves to categorise it as a medically unexplained symptom (MUS). This is puzzling on a scientific level, and seriously retrogressive at a healthcare level.
It is nearly 50 years since Melzack and Wall published their gate control theory,3 presenting an integrated model of physiological and psychological processing, and challenging existing dualistic interpretations of many pain phenomena:
‘The contemporary custom of assigning the cause of pain either to peripheral pathology or to mental pathology is too simple because it ignores the subtle dynamic properties of peripheral tissue and of the nervous system … which could explain many … diseases … which have previously been attributed to mental disorders.’3
On the basis of that model, understanding of the mechanisms underlying pain — some of which involve psychological and social factors — has deepened, although effective treatments have been slower to emerge.
NEUROPHYSIOLOGY EXPLAINS THE ‘UNEXPLAINED’
A minority of pains continue despite attempts to treat them: chronic or persistent pain. Whatever the (presumed) origin of the pain, there is increasing recognition that specific central nervous system mechanisms account for persistence through changes in structure and function of neurons at peripheral, spinal cord, and brain levels. Peripheral and central sensitisation facilitates and amplifies pain transmission and depresses its inhibition.4 Again, almost regardless of origin or site of pain, imaging of brain processing and behavioural studies show consistent changes,5 leading to serious suggestions that persistent pain may be considered a disease in its own right.5
Despite these consistent evidence-based explanations, reports of pain which are judged not to correspond to physical signs have long been classified as a ‘somatisation’ phenomenon (a recent review6 exposes the poor scientific basis of this), and more recently as medically unexplained. Pain is very heavily represented in any of the varied lists of MUS.7
The concept of MUS has been criticised for its dualism and the fact that the term MUS is a barrier in itself to improved care.8 Yet, the concept of MUS has been embraced by primary care commissioners and primary care mental health services (the Improving Access to Psychological Therapies [IAPT] programme), in whose documents chronic pain is described helpfully as a long-term condition (associated with anxiety, depression and disability) and unhelpfully as a MUS, attributable to anxiety and/or depression.9 Although much of the clinical advice is appropriate, the attribution of patients' struggle with pain to psychological disorder undermines the therapeutic relationship.10 Misunderstandings of pain as a danger signal underlie voluntary restriction of activity and withdrawal from normal activities.11 The practitioner's role in explaining pain and its relationship with beliefs and emotions is key to engaging the patient in rehabilitative treatment.1
EVIDENCE-BASED TREATMENT
The crudest model of pain as a MUS appears in a document supporting London commissioning of services:12 any presentation where ‘symptoms do not fit with findings’ should be considered ‘medically unexplained’. GPs are encouraged to search electronic records for frequently attending patients, and to filter by report of chronic or multiple pains, or by prescription of opioids, pregabalin, or gabapentin, then to refer to mental health services. No reference is made to Cochrane reviews and NICE guidance which support the prescription of these drugs for chronic pain.
Any GP will tell you that interrogating databases using these parameters is likely to identify a multitude of patients: around 11% of adults have chronic pain and many consult frequently.1 As for a diagnosis of MUS if a ‘patient cannot give a clear or precise description’; welcome to a normal surgery. After all, general practice can be characterised as the art of unravelling the medically unexplained.
The Commissioning Support for London document12 threatens to redirect patients with chronic pain to IAPT practitioners without adequate — or any — training in pain management. This will overwhelm the IAPT service, and commit patients to yet another inappropriate treatment. Pathways for assessment and treatment in primary care are currently in development under the auspices of the British Pain Society and Map of Medicine. Unlike the proposals based on pain as medically unexplained, these pain treatment pathways are evidence-based, practical, and take full account of patients' needs.
The ubiquity and familiarity of pain, and the difficulties of dealing with symptoms without signs, contribute to the failure to take seriously the phenomenon of persistent pain and the mechanisms which explain it.1,2 The resurgence of an unscientific and patient-unfriendly MUS model for pain is to be deplored.
Notes
Provenance
Freely submitted; not externally peer reviewed.
- © British Journal of General Practice 2011
