Guidelines Clinical Practice
Copyright ©2009 The WJG Press and Baishideng. All rights reserved.
World J Gastroenterol. Jan 14, 2009; 15(2): 151-159
Published online Jan 14, 2009. doi: 10.3748/wjg.15.151
Sensory testing of the human gastrointestinal tract
Christina Brock, Lars Arendt-Nielsen, Oliver Wilder-Smith, Asbjørn Mohr Drewes
Christina Brock, Mech-Sense, Department of Gastroenterology, Aalborg Hospital, DK-9000 Aalborg, Denmark
Lars Arendt-Nielsen, Center for Sensory-Motor Interactions, Department of Health Science and Technology, Aalborg University, DK-9000 Aalborg, Denmark
Oliver Wilder-Smith, Pain and Nociception Research Group, Department of Anaesthesiology, Radboud University Nijmegen Medical Centre, the Netherlands
Asbjørn Mohr Drewes, Mech-Sense, Department of Gastroenterology, Aalborg Hospital, DK-9000 Aalborg, Denmark
Author contributions: All authors have contributed to the manuscript.
Correspondence to: Asbjørn Mohr Drewes, Professor, MD, PhD, DMSc, Mech-Sense, Department of Gastroenterology, Aalborg Hospital, DK-9000 Aalborg, drewes@hst.aau.dk
Telephone: +45-99321111
Fax: +45-99326507
Received: September 10, 2008
Revised: November 24, 2008
Accepted: November 30, 2008
Published online: January 14, 2009
Abstract

The objective of this appraisal is to shed light on the various approaches to screen sensory information in the human gut. Understanding and characterization of sensory symptoms in gastrointestinal disorders is poor. Experimental methods allowing the investigator to control stimulus intensity and modality, as well as using validated methods for assessing sensory response have contributed to the understanding of pain mechanisms. Mechanical stimulation based on impedance planimetry allows direct recordings of luminal cross-sectional areas, and combined with ultrasound and magnetic resonance imaging, the contribution of different gut layers can be estimated. Electrical stimulation depolarizes free nerve endings non-selectively. Consequently, the stimulation paradigm (single, train, tetanic) influences the involved sensory nerves. Visual controlled electrical stimulation combines the probes with an endoscopic approach, which allows the investigator to inspect and obtain small biopsies from the stimulation site. Thermal stimulation (cold or warm) activates selectively mucosal receptors, and chemical substances such as acid and capsaicin (either alone or in combination) are used to evoke pain and sensitization. The possibility of multimodal (e.g. mechanical, electrical, thermal and chemical) stimulation in different gut segments has developed visceral pain research. The major advantage is involvement of distinctive receptors, various sensory nerves and different pain pathways mimicking clinical pain that favors investigation of central pain mechanisms involved in allodynia, hyperalgesia and referred pain. As impairment of descending control mechanisms partly underlies the pathogenesis in chronic pain, a cold pressor test that indirectly stimulates such control mechanisms can be added. Hence, the methods undoubtedly represent a major step forward in the future characterization and treatment of patients with various diseases of the gut, which provides knowledge to clinicians about the underlying symptoms and treatment of these patients.

Keywords: Endoscopy, Intestine, Experimental, Neurophysiology, Pain