Anorectal functioning in fecal incontinence.

Manometric testing was performed on three groups of subjects: 14 patients complaining of fecal incontinence, 14 age- and sex-matched continent patients, and 14 sex-matched younger normal controls. The younger group displayed significantly stronger contractions of the external anal sphincter and puborectalis than the two patient groups, which did not differ. No differences were found in the relaxation of the internal and sphincter. The incontinent group required a significantly larger stimulus in order to detect rectal distension compared to either the continent patients or the younger normals. An additional group of unmatched normals and incontinent patients demonstrated significant differences in their ability to retain rectally infused saline. The patients leaked sooner and retained less; however, the performance of the normals was considerably reduced from that reported in previous studies. The aging process seems to result in weakening of the striated muscles of the anal canal, although fecal incontinence need not occur. The afferent limb of the anorectal sensorimotor mechanism does not necessarily deteriorate with aging. A lower threshold for sensation of rectal distension among continent individuals apparently helps them to avoid incontinent episodes, even though maximum contractile pressures in their anal canal are no different from a comparable group of incontinent individuals.