Patterns of abnormal pudendal nerve function that are associated with postpartum fecal incontinence

The purpose of this study was to assess patterns of abnormal pudendal nerve function in women who complain of postpartum fecal incontinence.

During a 12-month period, a cohort of 83 women underwent neurophysiologic assessment as part of an evaluation of fecal incontinence after vaginal delivery. Pudendal nerve assessment consisted of the measurement of the clitoral-anal reflex and quantitative electromyography of the external anal sphincter. Endoanal ultrasound examination and anal manometry were also performed in each patient.

Thirty of 83 women (38%) with fecal incontinence were found to have abnormal neurophysiologic condition, among whom four identifiable patterns of abnormality emerged. Five women (17%) had evidence of pudendal nerve demylenation with a prolonged sensory threshold of the clitoral-anal reflex (>5.2 mA), although electromyography studies were normal. Eight women (27%) had abnormal electromyography results that were consistent with axonal neuropathy with or without reinervation, in whom the clitoral-anal reflex was normal. Thirteen women (43%) demonstrated a mixed demyelinating and axonal pudendal neuropathy, with evidence of reinervation. Four women (13%) had abnormal patterns of neurophysiologic condition that was not attributable directly to past obstetric trauma but to coincident medical problems.

Four abnormal patterns of pudendal nerve function may be identified, three of which (demyelinating, axonal, and mixed demyelinating/axonal) can be attributed to specific past obstetric events, although a fourth radicular pattern is due to coincident medical or orthopedic problems. Assessment of pudendal nerve function is important in women with postpartum fecal incontinence because particular patterns of abnormality correlate with different symptoms and can influence treatment options.