REPETITIVE SIGMOID STIMULATION INDUCES RECTAL HYPERALGESIA IN PATIENTS WITH IRRITABLE-BOWEL-SYNDROME

Background & Aims: Only a fraction of patients with irritable bowel sy ndrome (IBS) show hypersensitivity to rectal distention, The current s tudy sought to determine if repetitive high-pressure stimulation of si gmoid mechanoreceptors modulates perception of rectal pain and discomf ort. Methods: In 14 patients with IBS and 11 healthy controls, percept ion thresholds for discomfort and pain during rectal sensory tracking and verbal descriptor ratings of the perceived intensity of a rectal t onic stimulus were obtained before and after repetitive high-pressure mechanical sigmoid stimulation, Gastrointestinal and psychological sym ptoms were assessed by questionnaires, Results: Despite heterogeneity in baseline rectal sensitivity in patients with IBS, after sigmoid sti mulation, 100% of patients, regardless of baseline sensitivity, develo ped rectal hyperalgesia manifested by at least two of the following th ree criteria: lowered thresholds for pain and discomfort and increased viscerosomatic referral and lower abdominal discomfort outlasting the experimental stimulation. This pattern of responses was not observed in any of the healthy controls, Conclusions: In patients with IBS, rep etitive stimulation of sigmoid splanchnic afferents results in the dev elopment of central sensitization manifested as hyperalgesia and incre ased viscerosomatic referral during rectal distention and as spontaneo us rectosigmoid hyperalgesia in the absence of applied stimuli, Repeti tive sigmoid contractions may induce rectosigmoid hyperalgesia in pati ents with IBS.