Anorectal temperature sensation: a comparison of normal and incontinent patients

In the skin, temperature sensation plays an important role in discriminating between gas, liquid and solid. To elucidate the role of temperature sensation in idiopathic faecal incontinence we studied the minimum detectable temperature change in the lower, middle and upper zones of the anal canal and rectum in 33 normal subjects, and 20 patients with idiopathic faecal incontinence. A water perfused thermode was used to vary anorectal temperature from 37 degrees C down to 32.5 degrees C and up to 41.5 degrees C. The temperature change was reported by the patient as the thermode temperature varied from 37 degrees C to each extreme and on return to base line. The anal canal in the control group was highly sensitive to temperature change, the lower rectum was significantly less sensitive (P less than 0.0001). At each level in the anal canal and lower rectum the incontinent group were significantly less sensitive than their controls (P less than 0.005). The mid-rectum had no appreciable sensation in either group. We consider that this sensory deficit may be an important factor in idiopathic faecal incontinence.