PUDENDAL NERVE LATENCY - DOES IT PREDICT OUTCOME OF ANAL-SPHINCTER REPAIR

PURPOSE: Electrophysiologic evaluation has been suggested as a means o f identifying prognostic factors for patients with fecal incontinence who undergo anal sphincter repair. The purpose of this study was to ev aluate the results of anal sphincter repair in patients with documente d pudendal neuropathy and to determine the usefulness of electrophysio logic studies for prognostication of sphincteroplasty. METHODS: A retr ospective review of a series of patients undergoing electrophysiologic studies and anterior anal sphincteroplasty was performed. Data collec ted included age, standardized incontinence scores (preoperative, imme diately postoperative, and current follow-up), and results of pudendal nerve terminal motor latency and monopolar electromyography. Outcomes of sphinctero plasty were designated as excellent, good, fair, or poo r based on incontinence scores. Prolonged pudendal nerve terminal moto r latency was defined as longer than 2.2 ms and evaluated as unilatera l of bilateral. RESULTS: During the time period of the study (1991-199 6), 15 patients had electrophysiologic studies and underwent sphincter oplasty. Twelve patients (80 percent) were available for follow-up and form the basis for this study. All patients were women, with a mean a ge of 45 +/- 18.6 (27-75) pears and a mean follow-up of 49.7 +/- 18.6 (20.4-72.6) months. Mean duration of incontinence preoperatively was 1 3 +/- 16.1 (range, 1-58) years. The incontinence score was 15.8 +/- 3. 5 preoperatively, 5.4 +/- 4.5 postoperatively, and 5 + 5.1 currently f or all 12 patients. There was one patient with normal pudendal nerve t erminal motor latency. In the four patients with bilateral prolonged p udendal nerve terminal motor latency, the incontinence scores were 15 +/- 4.2 preoperatively, 8.5 +/- 5.3 postoperatively, and 6 +/- 6.1 (st atistically significant compared with preoperation) currently. Seven p atients were found to have unilateral prolonged pudendal nerve termina l motor latency with incontinence scores of 16.3 +/- 3.5 preoperativel y, 4.4 +/- 3.2 (statistically significant compared with preoperation) postoperatively, and 5.1 +/- 4.9 (statistically significant compared w ith preoperation) currently. Based on incontinence scores, results of the sphincteroplasty at the most current followup were as follows: no neuropathy, excellent in one patient; unilateral neuropathy, five with good/excellent results, two with fair/poor results; bilateral neuropa thy, two with good/excellent results, two with fair/poor results (P > 0.05 bilateral vs. unilateral). By monopolar electromyographic examina tion, external anal sphincter denervation was noted in 11 patients; th eir incontinence scores were 15.5 +/- 3.5 preoper atively, 5.9 +/- 4.3 (statistically significant compared with preoperation) postoperativel y, and 5.5 +/- 5.0 (statistically significant compared with preoperati on) currently. Monopolar electromyographic results in the puborectalis included four normal examinations and six that were unobtainable. In the two patients with puborectalis denervation, the incontinence score s were 19.5 +/- 0.7 preoperatively, 8.5 +/- 4.9 postoperatively, and 2 .5 +/- 3.5 (statistically significant compared with preoperation) curr ently. CONCLUSIONS: Anterior anal sphincteroplasty in patients with un ilateral or bilateral prolonged pudendal nerve terminal motor latency can provide significant improvement in continence with minimum morbidi ty. Therefore, correction of the anatomic sphincter defect should stil l be considered, even in patients with documented pudendal neuropathy.