Pudendal neuropathy and the importance of EMG evaluation of fecal incontinence

Abstract

A prospective study was undertaken to evaluate pudendal neuropathy in fecal incontinence. Fifty-two patients (38 women and 14 men) with fecal incontinence underwent manometric and electromyographic evaluation (measurement of pudendal nerve terminal motor latency [PNTML] and sphincter muscle mapping). The average age of all patients was 54 +/- 17 years. Fifty-two percent (27/52) were found to have a pudendal neuropathy (PNTML > 2.1 milliseconds). Seventeen of these 27 patients (63 percent) had a bilateral pudendal neuropathy. Patients with a pudendal neuropathy were older than those without a neuropathy (63.7 years vs. 51.9 years; P = 0.01). Women were significantly more likely than men to have a pudendal neuropathy (P = 0.03). Nine patients had an anatomic sphincter defect identified, and six of these (67 percent) had a neuropathy; 4/6 (67 percent) had a bilateral pudendal neuropathy. In the 43 patients who did not have an anatomic sphincter defect, there was no difference in resting pressure (69 mmHg vs. 60 mmHg; P = 0.4) or maximum voluntary contraction (95 mmHg vs. 86 mmHg; P = 0.5) when patients without a neuropathy were compared with those with a neuropathy. Patients with a pudendal neuropathy had a shorter sphincter length than those without a neuropathy (3.0 cm vs. 3.9 cm; P = 0.01). Bilateral pudendal neuropathy tended to occur more frequently in women (P = 0.08) and was not associated with poorer resting pressure, maximum voluntary contraction, or shorter sphincter length. We conclude that pudendal neuropathy is a common cause of fecal incontinence, particularly in older women, and frequently occurs in association with a sphincter defect. Manometric evaluation alone is not helpful in identifying the neuropathic patient. PNTMLs should be routinely measured in the evaluation of fecal incontinence.