Hypersensitivity to cutaneous thermal nociceptive stimuli in irritable bowel syndrome

• Published in: Pain (Amsterdam) Vol. 115; no. 1; pp. 5 - 11
• Main Authors: Rodrigues, Anthony C., Nicholas Verne, G., Schmidt, Siegfried, Mauderli, Andre P.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-05-2005; Elsevier
• Subjects: Adult; Biological and medical sciences; Chronic pain disease; Cutaneous stimulus; Female; Fundamental and applied biological sciences. Psychology; Gastroenterology. Liver. Pancreas. Abdomen; Hot Temperature - adverse effects; Humans; Hyperalgesia - diagnosis; Hyperalgesia - physiopathology; Irritable bowel syndrome; Irritable Bowel Syndrome - diagnosis; Irritable Bowel Syndrome - physiopathology; Medical sciences; Middle Aged; Nervous system involvement in other diseases. Miscellaneous; Neurology; Other diseases. Semiology; Pain; Pain - diagnosis; Pain - physiopathology; Pain Measurement; Pain sensetization; Pain Threshold; Physical Stimulation - methods; Skin - innervation; Skin - physiopathology; Somesthesis and somesthetic pathways (proprioception, exteroception, nociception); interoception; electrolocation. Sensory receptors; Stomach. Duodenum. Small intestine. Colon. Rectum. Anus; Thermal stimulus; Vertebrates: nervous system and sense organs; Thermal stimulus; Pain; Cutaneous stimulus; Chronic pain disease; Pain sensetization; Irritable bowel syndrome; Dermatome; Human; Pain sensitivity; Noxious stimulus; Hypersensitivity; Thermal sensitivity; Convergence; Digestive diseases; Intestinal disease; Perception; Sensitization
• ISSN: 0304-3959; 1872-6623
• DOI: 10.1016/j.pain.2005.01.023

Irritable bowel syndrome (IBS) is a common intestinal ailment of which the pathophysiological mechanisms are not well understood. Most IBS patients demonstrate enhanced perception, visceral hypersensitivity, in response to distension of the gut lumen but there are conflicting results about changes in somatic sensitivity. This study focused on the possible contribution of abnormal pain sensitization due to positive feedback (vicious pain cycle) that affects somatic tissues due to viscero-somatic convergence. The specific objectives were to measure cutaneous thermal pain sensitivity along the segmental axis, including in dermatomes that are remote from the visceral pain focus. Pain sensitivity was probed with cutaneous thermal stimulation to the lower and upper extremities and the face in nine diarrhea-predominant IBS patients (diagnosed with ROME II criteria) and 12 healthy female controls. The stimuli were administered with a contact thermode, assuring that size of the stimulated area and stimulus duration were clearly defined and identical in all locations. Sensitization of IBS patients was not limited to symptomatic dermatomes (calf) but extended evenly across the body, including to the face (no sensitization gradient from foot to face). Also, the difference between IBS and control groups did not depend on the evoked pain intensity level, i.e. the degree of sensitization of IBS patients was similar near threshold (10% on the visual analog scale) and at higher intensities. Lastly, no correlation was found between IBS subjects' pain sensitivity of any of the three test sites and their ratings of spontaneous pain.