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Our aim was to compare rectal perception of patients with diarrhea-predominant irritable bowel syndrome (IBS-D), constipation-predominant irritable bowel syndrome (IBS-C), functional constipation (FC), and healthy controls and to evaluate the therapeutic effect of acupoint transcutaneous electric nerve stimulation (TENS). Age- and sex-matched patients (24 IBS-D, 20 IBS-C, and 30 FC) were selected, and 30 volunteers served as healthy controls. Rectal sensory thresholds were evaluated by rectal balloon distension. Short- and long-term acupoint TENS was given respectively. IBS-D patients had significantly lower rectal sensory thresholds of the first sensation of stool, urgency of defecation, and pain than IBS-C or FC patients or healthy controls (P < 0.05), but there were no differences in rectal sensory thresholds among IBS-C and FC patients and healthy controls. In each group, females had significantly lower rectal sensory thresholds than males (P < 0.05), but there was no difference between younger (< or =50 years old) and older (>50 years old) patients. Short-term acupoint TENS increased rectal sensory thresholds of IBS-D patients. After 2-month acupoint TENS treatment in IBS-D patients, rectal sensory thresholds were significantly increased, stool times and the intensity of abdominal pain were decreased, and psychological scores were relieved to normal. Lowered rectal perception threshold is a hallmark of IBS-D patients. Females have significantly lower rectal sensory thresholds than males. Acupoint TENS is effective to treat IBS-D.
KEY WORDS: irritable bowel syndrome; visceral hypersensitivity; TENS.
Irritable bowel syndrome (IBS) is very common and often characterized by lower abdominal pain with disturbed defecation in the absence of organic abnormalities that might explain these symptoms (1-3). Many research groups have demonstrated lowered sensory thresholds to rectal distention in IBS patients. A lowered rectal pain threshold is a hallmark of IBS patients and can be useful to confirm the diagnosis of IBS and to discriminate IBS from other causes of abdominal pain (4, 5). IBS has a strong predominance in women and a variety of reasons for this ob- servation has been suggested, ranging from psychosocial to physiological factors (6). Sensory differences have been noted in esophagus, with healthy females exhibiting lowered pain thresholds to balloon distension than males (7). However, direct evidence of lowered rectal sensory thresholds in females is lacking. In addition, IBS consists of various subtypes. There...