Alterations in cerebral potentials evoked by rectal distention and drinking ice water in patients with irritable bowel syndrome

Aim: Visceral hypersensitivity has been found to be present in irritable bowel syndrome (IBS). The current study sought to study visceral afferent hypersensitivity in IBS patients and obtain further objective evidence of alterations in intestinal afferent pathways in IBS patients by cerebral evoked potentials (CEP). Method: We studied 30 female IBS patients and 12 female healthy subjects. Rectal perception thresholds to balloon distention were measured and CEP was recorded in response to rhythmic rectal distention (two distention series, each of 100 repetitions at a frequency of 1 Hz) at the volume of perception thresholds. All subjects were then asked to drink 220 mL 4 degrees C ice water and the above steps were repeated 20 min later. Results: Rectal distention led to recognizable and reproducible CEP. Compared to healthy subjects, IBS patients demonstrated significantly shorter N-1, P-1 and N-2 latencies (P < 0.05). After drinking ice water, IBS patients exhibited further shortened N-1, P-1 and N-2 latencies (P < 0.05), but drinking did not alter the latencies of healthy controls and the amplitudes of both IBS patients and healthy controls. Conclusion: The shorter latency of cerebral potentials evoked by rectal distention and ice water stimulation in IBS patients provided further objective evidence for defective visceral afferent transmission in IBS patients.