Alterations in cerebral potentials evoked by rectal distension in irritable bowel syndrome

Central nervous system correlates of the visceral hyperalgesia documented in patients with irritable bowel syndrome are limited. Reproducible cerebral evoked potentials can be recorded in response to rhythmic balloon distension of the rectum in healthy adults. Irritable bowel syndrome patients and healthy subjects were studied to compare the characteristics of mechanically-evoked rectal cerebral potentials obtained during fasting and after the ingestion of a standard meal.

Twenty-two pairs of age-matched healthy female subjects and female irritable bowel syndrome patients were studied. Cerebral evoked potentials were recorded in response to rhythmic rectal distension (two distension series each of 100 repetitions at 0.8 hertz); cerebral evoked potential recordings were repeated after a 1000 kcal (46% fat) liquid meal. Trait and state anxiety questionnaires were also completed.

Compared to healthy subjects, irritable bowel syndrome patients demonstrated higher prevalence of cerebral evoked potential early peaks (latency < 100 ms) postprandially, and uniformly shorter cerebral evoked potential latencies both before and after feeding.

These findings provide further objective evidence for defective visceral afferent transmission in irritable bowel syndrome patients.