Introduction

A biopsychosocial understanding of chronic abdominal pain requires integrating the biological processes affecting the pain, both peripheral and central, with knowledge of the contributing psychosocial factors (1). In effect, it is the brain-gut modulation of both enteroceptive (i.e., gut related) and extrinsic (i.e., environmental and stress related) influences on sensation that are unique to the individual. Although nociceptive signals increase with heightened motor reactivity and visceral...

Heat Allodynia and Hyperalgesia in Fibromyalgia Patients

There are pain conditions that, unlike CRPS described above, are characterized by diffuse pains and hyperalgesia over large areas of body. The ability to use the same patients as their own control in establishing hyperalgesia and allodynia is therefore more challenging in these patient populations. An alternative approach is to compare their ratings of experimental heat stimuli to groups of age- and sex-matched control subjects. For example, heat hyperalgesia has been shown to be a prevalent...

Gonadal Hormone Modulation Of Visceral Pain

The preponderance of evidence suggests that females are more sensitive to pain than males and several chronic pain syndromes including IBS, fibromyalgia, and temporomandibular disorders are more prevalent in women than in men 197-199 . Furthermore, nociceptive thresholds are lowest and pain responses highest during periods of elevated estrogen 199-204 , strongly suggesting that sex hormones modulate pain sensation. Several labs have demonstrated that gonadal hormones modulate behavioral...

Evidence of Heat Hyperalgesia in Irritable Bowel Syndrome Evidence from Human Irritable Bowel Syndrome Patients

The first study to show large magnitudes of heat hyperalgesia in IBS patients compared VAS ratings of pain intensity and unpleasantness in response to rectal distension and cutaneous thermal stimuli in 12 patients with IBS but without fibromyalgia and in 17 healthy controls 40 . Using methods similar to those of other investigators 41,42 , phasic distension of the rectum 870 mL min to constant pressure plateaus of 35 and 55 mmHg for 30 seconds each were performed, followed by a 60-second...

Visceral Pain Is Referred to Somatic Structures

The initial perception of pain from the viscera is described as diffuse pain along the midline of the trunk 3,2 . It is poorly localized relative to the originating tissue. This likely results from the divergent central projection of visceral afferent fibers synapsing with scores of dorsal horn neurons in many segments. As the pain intensifies, it is more clearly referred to somatic tissue. It is perceived as originating from the area of the body that is innervated by somatic primary afferent...