Results of neurophysiologic evaluation in fecal incontinence

PURPOSE: Several methods of neurophysiologic assessment exist in the invest igation of patients with fecal incontinence. However, the clinical signific ance of the information gained is uncertain. The aim of this prospective st udy was to evaluate the results of pudendal nerve terminal motor latency an d fiber density in relation to clinical variables and manometric measuremen ts. METHODS: Seventy-two patients with fecal incontinence (63 women; mean a ge, 62; range, 24-81 years) responded to a bowel questionnaire and underwen t anorectal manovolumetry, anal ultrasonography, defecography, and electrom yography, including pudendal nerve terminal motor latency and fiber density . RESULTS: Pudendal neuropathy (pudendal nerve terminal motor latency > 2.5 ms) was found in 46 percent and increased fiber density (>1.7) in 82 perce nt. Pudendal neuropathy and increased fiber density were most common in pat ients 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 increase d fiber density had lower incremental pressures (P < 0.05) and stated decre ased rectal sensibility (P < 0.05) compared with those with normal fiber de nsity. These differences were most pronounced in patients with neurogenic o r idiopathic incontinence. CONCLUSIONS: Pudendal neuropathy and increased f iber 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 incon tinence. The routine use of pudendal nerve terminal motor latency in the as sessment of patients with fecal incontinence can be questioned.