Results of neurophysiologic evaluation in fecal incontinence

Several methods of neurophysiologic assessment exist in the investigation of patients with fecal incontinence. However, the clinical significance of the information gained is uncertain. The aim of this prospective study was to evaluate the results of pudendal nerve terminal motor latency and fiber density in relation to clinical variables and manometric measurements.

Seventy-two patients with fecal incontinence (63 women; mean age, 62; range, 24-81 years) responded to a bowel questionnaire and underwent anorectal manovolumetry, anal ultrasonography, defecography, and electromyography, including pudendal nerve terminal motor latency and fiber density.

Pudendal neuropathy (pudendal nerve terminal motor latency > 2.5 ms) was found in 46 percent and increased fiber density (> 1.7) in 82 percent. Pudendal neuropathy and increased fiber density were most common in patients with rectal prolapse or intra-anal intussusception. No difference was seen concerning anal resting and incremental pressures, rectal compliance, rectal sensibility or severity of incontinence in patients with unilateral, bilateral, or marked (> 4 ms) pudendal neuropathy vs. patients with normal pudendal nerve terminal motor latency. In contrast, patients with increased fiber density had lower incremental pressures (P < 0.05) and stated decreased rectal sensibility (P < 0.05) compared with those with normal fiber density. These differences were most pronounced in patients with neurogenic or idiopathic incontinence.

Pudendal neuropathy and increased fiber density are common in patients with fecal incontinence. Fiber density but not pudendal nerve terminal motor latency was correlated with clinical and manometric variables. The severity of nerve injury correlated with anal motor and sensory function in patients with neurogenic or idiopathic incontinence. The routine use of pudendal nerve terminal motor latency in the assessment of patients with fecal incontinence can be questioned.