Original Contribution
The American Journal of Gastroenterology (2004) 99, 1990–1997; doi:10.1111/j.1572-0241.2004.30028.x
Acupuncture has a Placebo Effect on Rectal Perception but not on Distensibility and Spatial Summation: A Study in Health and IBS
Reingard BK Rohrböck MD1, Johann Hammer MD1, Harald Vogelsang MD1, Nicholas J Talley MD, PhD1 and Heinz F Hammer MD1
1Abteilung für Gastroenterologie und Hepatologie, University of Vienna, Austria; Mayo Clinic Center, Rochester, Minnesota; Medizinische Universitätsklinik Graz, Austria
Correspondence: Univ.-Prof. Dr. Johann Hammer, Universitätsklinik für Innere Medizin IV, Abteilung für Gastroenterologie und Hepatologie, Währinger Gürtel 18-20, A-1090 Vienna, Austria
Received 6 February 2004; Revised 0000; Accepted 13 April 2004.
Abstract
BACKGROUND:
Recent data suggest that acupuncture has effects on gut physiology and perception. Spatial summation is a central mechanism of perception and describes the phenomenon that thresholds for perception are lower if more receptors are stimulated.
OBJECTIVES:
We assessed perception thresholds for rectal distension and cutaneous referral of symptoms, while inflating one or two rectal balloons and the effect of both electro-acupuncture and placebo-acupuncture on rectal distensibility, perception, and spatial summation.
METHODS:
A tube with two barostat balloons was placed in the rectum of 12 healthy subjects and nine irritable bowel syndrome (IBS) patients with rectal symptoms. Volume-controlled stepwise distension of the distal balloon only or both balloons was performed first as a control, and thereafter with simultaneous placebo- or electro-acupuncture in dermatomes S3 and S4. A symptom questionnaire and anatomic questionnaire was completed during each distension.
RESULTS:
Rectal elastance increased from 42.0 
19.6 log mmHg/ml during one-balloon distension to 59.6 33.1 log mmHg/ml during two-balloon distension (p < 0.05) in healthy subjects, and from 48.8 14.4 log mmHg/ml (one balloon) to 77.6 24.2 log mmHg/ml (p < 0.001) in patients with IBS. Electro-acupuncture had no effect on rectal sensation, elastance, and cutaneous referral when compared to placebo-acupuncture. However, acupuncture (both electro- and placebo-) increased volume thresholds for sensation compared to control experiments, while objective parameters like rectal tone and elastance were unaltered.
CONCLUSIONS:
Acupuncture has a placebo effect on rectal perception but has no effect on rectal distensibility and visceral referral. Spatial summation affected both rectum distensibility and perception, but was also not altered by acupuncture.
