The effects of biofeedback on rectal sensation and distal colonic motility in patients with disorders of rectal evacuation: evidence of an inhibitory rectocolonic reflex in humans?

OBJECTIVE: Abnormalities of descending colon motility reported in a subset of patients with rectal evacuation disorders are consistent with a rectocolonic inhibitory reflex. Our aims were to evaluate distal colon motor function and rectal sensation in such patients and assess effects of biofeedback (BF) training on these functions. METHODS: Seven patients (five women, two men; mean age 36 yr) with rectal evacuation disorders were studied before and after 10-days biofeedback training; six healthy volunteers (five women, one man; mean age 30 yr) were studied once. Colonic compliance, motility, sensation thresholds, and perception scores during standardized rectal distentions were measured using two barostat-manometry assemblies inserted into the cleansed colon with the aid of flexible sigmoidoscopy. RESULTS: Sigmoid compliance, fasting, and postprandial motility index, and perception thresholds were similar in controls and patients before and after biofeedback training. Postprandial sigmoid tone tended (p = 0.09) to be lower in patients than controls; after biofeedback, postprandial tone was comparable to that in controls. Rectal urgency scores at 24 mm Hg distention were greater in patients than in controls (p = 0.02 for both). After biofeedback, there were trends for lower perceptions of urgency to defecate (7.6 ± 1.1 cm pre- vs 5.3 ± 1.5 post-; p = 0.04) at 24 mm Hg; conversely, gas sensation at 12 mm Hg was higher (1.2 ± 0.5 cm pre- vs 3.3 ± 0.6 post-; p = 0.05). CONCLUSIONS: Normalization of rectal evacuation and postprandial sigmoid tone in patients with evacuation disorders by biofeedback training supports the presence of a rectocolonic inhibitory reflex. Effect of biofeedback on rectal sensation in these patients requires further study.