Pudendal Neuropathy Alone Results in Urge Incontinence Rather Than in Complete Fecal Incontinence.

Background: Conscious external anal sphincter contraction is mediated by the pudendal nerve. Pudendal neuropathy is, therefore, believed to result in fecal incontinence. Until urge sensation is experienced, fecal continence is maintained by unconscious external anal sphincter contraction, which is regulated by the anal-external sphincter continence reflex. The innervation of unconscious contraction is yet unknown.

Objective: We aimed to determine whether unconscious contraction is mediated by the pudendal nerve and whether age influences unconscious contraction.

Design: This was a retrospective comparative study.

Settings: The study was conducted in a tertiary care center.

Patients: Seventy adult patients experiencing defecation problems who underwent anorectal function tests were included in this study.

Main Outcome Measures: Conscious and unconscious contractions were compared between patients with and without pudendal neuropathy. Conscious contraction was defined by maximum anal sphincter contractility, unconscious contraction by pressure in the anal canal at maximum tolerable or retainable sensation during the balloon retention test.

Results: Unconscious contraction did not differ significantly between patients with pudendal neuropathy and non-pudendal neuropathy patients, whereas conscious contraction was significantly lower in patients with pudendal neuropathy. Multiple linear regression analyses demonstrated that unconscious contraction, in contrast to conscious contraction, was not predicted significantly by age and anal electrosensitivity at 2 cm, which represents pudendal neuropathy. Patients with pudendal neuropathy were significantly older than patients with nonpudendal neuropathy.

Limitations: The pudendal nerve motor latency and EMG tests were not performed.

Conclusions: The pudendal nerve does not mediate unconscious external anal sphincter contraction. Pudendal neuropathy alone, therefore, results in urge incontinence rather than in complete fecal incontinence. Unconscious contraction appears not to be influenced by age. Therefore, most of the elderly patients experience urge incontinence rather than complete fecal incontinence.