Constipation in the elderly. A physiologic study.

Colorectal motility was studied in 25 elderly patients with chronic constipation and compared with an asymptomatic control group (N = 17). Proctometrograms were performed to measure rectal volumes at sensory threshold and maximal tolerance, and rectal compliance. Anal sphincter pressures and reflexes were measured by conventional techniques. Indices of colonic motility were also assessed. Significant impairment of rectal sensory threshold was apparent in constipation. Six patients presenting with impaction demonstrated functional megarectums. The remaining 19 showed a significant reduction in maximal rectal volume and rectal compliance and 14 extruded the balloon. There were no differences in sphincter length or presence of the rectosphincteric reflex. Four patients had an absent pudendoanal reflex and the remainder significant prolongation. Total gastrointestinal transit times were prolonged in the constipation group, mainly distally due to rectal stasis. In two patients bisacodyl failed to elicit a sigmoid motor response. Constipation in the elderly is not merely due to delayed transit. Neurogenic deficits of sacral spinal cord function may be responsible for abnormalities in rectal motor and sensory function.