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Gut 53:1553-1555 doi:10.1136/gut.2004.046110
  • Commentary

Importance of anti- and pro-nociceptive mechanisms in human disease

  1. I Tracey,
  2. P Dunckley
  1. Pain Imaging Neuroscience (PaIN) Group, Human Anatomy and Genetics Department and FMRIB Centre, Oxford University, Oxford, UK
  1. Correspondence to:
    Dr I Tracey
    Pain Imaging Neuroscience (PaIN) Group, Human Anatomy and Genetics Department and FMRIB Centre, Oxford University, South Parks Rd, Oxford OX1 3QX, UK; irene.traceyanat.ox.ac.uk

    Abnormalities in endogenous descending pain inhibitory and facilitatory influences probably contribute to the development and maintenance of chronic pain states

    The burden of chronic pain to society is enormous. This is both in terms of physical and emotional impact to individuals and carers, in addition to the large financial burden. Current estimates suggest that 11.5–55.2% of individuals worldwide are defined as suffering from chronic widespread pain.1 A major characteristic of functional disorders such as irritable bowel syndrome (IBS) and inflammatory/neuropathic disorders such as gastro-oesophageal reflux and chronic pancreatitis is abdominal discomfort or pain. There is an increasing awareness that many similarities exist mechanistically between somatic chronic pain conditions and the pain witnessed as chronic in IBS and chronic pancreatitis patients. With this realisation there has been a change of focus for researchers of both somatic and visceral pain conditions from peripheral structures as the preferred target of research to the central nervous system (CNS). It has long been recognised that the CNS has a major modulating nociceptive influence that alters resultant pain perception.2–4 Recent developments in neuroimaging have enabled CNS investigations of visceral pain processing in patients and controls and such studies have highlighted the additional relevance of cognitive and emotional factors in modulating pain perception from physical changes such as plasticity and sensitisation.5–7 Imaging studies have provided valuable objective information on what is inherently a subjective phenomenon, that for too long has relied upon patients giving a self report of their pain using coarse pain rating scales.8 Currently, there is a wider imaging literature on pain processing from somatic structures compared with visceral organs. This is probably because it is experimentally (and ethically) easier to perform somatic acute pain paradigms in healthy controls (for instance, using noxious thermal events) compared with more challenging …