[Investigation of visceral hyperesthesia in irritable bowel syndrome].

BACKGROUND: It has been well established that visceral hyperesthesia plays a role in the development of irritable bowel syndrome (IBS).

AIMS: 1. to detect the possible changes of visceral perception in different subtypes of IBS patients, 2. to analyze the difference of visceral hyperaesthesia in different subtypes of IBS, 3. to examine whether distension protocols (e.g. phasic or ramp distension) has any influence on sensory thresholds, 4. to analyze the differences of perception thresholds produced by phasic or ramp distension in different subtypes of IBS.

METHODS: 10 patients having colorectal polypectomy (control group) and 40 IBS patients were studied. The diagnosis was based on the Rome-II criteria. Diarrhoea-predominant, alternating and constipation-predominant subtypes were determined by the Talley bowel habit questionnaire. Sensory thresholds were detected by semi random ascending phasic and ramp rectosigmoid distension. Rectal dynamic compliance was calculated by using the dV/dP ratio.

RESULTS: 1. The pain thresholds determined by phasic distension were significantly lower in all subtypes of IBS. 2. Increased thresholds for pain were found in almost half of constipation-predominant IBS patient determined by ramp distension. Thus two distinct subgroups could be found based on the findings of ramp distension: a normosensitive and a hyposensitive group. 3. Rectal dynamic compliance was significantly higher both in the constipation-predominant and alternating subtype of IBS patients.

CONCLUSION: Visceral hyperesthesia can be detected in all types of IBS. Tolerance to physiologic stimuli could be observed in constipating IBS patients that is not related to the increase of rectal compliance.