The sensory discrimination training technique involves a series of brief balloon inflations, noting the volume that induces a sensation of the urge to defecate thereby establishing a current sensory threshold. The volume is subsequently reduced by 25% and a series of insufflations are repeated until the patient is able to promptly recognize the new stimuli. Once patients learn to associate the increase in intrarectal pressure with balloon inflation, the patient is encouraged to recognize sequentially smaller volumes of distention. Thus, after each session, new sensory thresholds are established. The mechanisms by which biofeedback training improves rectal perception are unclear. It is suggested that biofeedback training may recruit sensory neurons adjacent to damaged afferent pathways. However, the speed with which sensory thresholds improve during biofeedback suggests that patients use existing afferent pathways, but learn to pay more attention to weak sensations and to recognize their significance (discrimination training).
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