Summary

In response to perceived or experienced change, which is considered threatening to the individual, the central nervous system mounts a stereotypic response which decreases the sensitivity to somatic pain, modulates autonomic nervous system outflow, and activates the hypothalamic-pituitary-adrenal axis. Recent experimental evidence obtained in rats suggests that this response can be associated with an increase in visceral sensitivity. This response of the “emotional motor system” may or may not be associated with the conscious experience of feelings of fear or anxiety. Alterations in some of these response systems (antinociception, vigilance) may be responsible for the characteristic visceral hypersensitivity often seen in patients with functional gastrointestinal disorders.

Irritable bowel syndrome (IBS) is a chronic disorder of unknown aetiology characterised by exacerbations and remissions, which presents with symptoms of abdominal pain and discomfort, and alterations in bowel habits. Approximately two thirds of patients report abdominal pain as one of their symptoms, and abdominal pain is reported by 40% of patients when asked for their most bothersome symptom.1The occurrence of certain stressful life events is the most important factor in symptom exacerbation and in the first development of symptoms.2-5 A recent prospective study emphasised that life events of a sustained duration, associated with threats to the patient's security, are most commonly associated with symptom exacerbation.2 In addition to these symptoms referred to the digestive system, clinical experience and recent reports in the literature have demonstrated a variety of extraintestinal symptoms in these patients, including other pain syndromes such as fibromyalgia (FM)6 7 and interstitial cystitis.8Furthermore, there is a close overlap between IBS and anxiety disorders.9 This article reviews evidence for the involvement of supraspinal pain modulation systems in the reported visceral hypersensitivity in IBS patients. For more information on the general topic of visceral hyperalgesia, …