Unilateral pudendal neuropathy. Significance and implications

Obstetric trauma and excessive defecatory straining with perineal descent may lead to pudendal neuropathy with bilateral increase in pudendal nerve terminal motor latencies (PNTML). We have frequently observed unilateral prolongation of PNTML. Diagnostic and therapeutic implications of unilateral pudendal neuropathy are discussed.

Records of 174 patients referred to pelvic floor laboratory for anorectal manometry and PNTML testing were reviewed. Computerized and manometry was performed using dynamic pressure analysis, and PNTML was determined using a pudendal (St. Mark's) electrode.

No response was elicited from pudendal nerves to electric stimulation from both sides in 14 patients (8 percent) and from one side in 24 patients (13.8 percent). Bilateral PNTML determination was possible in only 136 patients (78 percent), of whom 83 patients (61 percent) had no evidence of neuropathy, revealing normal PNTML on both sides. Of 53 patients (39 percent) with delayed conduction in pudendal nerves, in 15 patients (28 percent), PNTML was abnormally prolonged on both sides, with an abnormal mean value for PNTML. In the remaining 38 patients (72 percent), PNTML was abnormal on one side; in 27 patients with an abnormal mean PNTML and in 11 patients with a normal mean PNTML.

A significant number of patients with pelvic floor disorders have only unilateral pudendal neuropathy. Patients with unilaterally prolonged PNTML should be considered to have pudendal neuropathy, despite normal value for mean PNTML. This fact may be relevant in planning surgical treatment and in predicting prognosis of patients with sphincter injuries.