Pudendal neuropathy is predictive of failure following anterior overlapping sphincteroplasty

PURPOSE: This study assessed the efficacy of anterior overlapping sphincteroplasty and parameters predictive of a successful outcome. METHODS: Clinical findings and physiologic investigations of female patients who underwent anterior overlapping sphincteroplasty for fecal incontinence between 1988 and 1996 were reviewed. The extent of sphincter damage was assessed at needle electromyography as the number of quadrants exhibiting decreased motor unit potentials. Prolonged pudendal nerve terminal motor latencies were those of greater than 2.2 ms. The size of the endoanal ultrasound defect was assessed as degrees circumference of the external sphincter in which viable muscle was absent. Patients were reviewed by telephone questionnaire and were asked to grade the outcome of their surgery as excellent or good (success) or fair or poor (failure). Incontinence was graded using a scoring system of 0 (perfect continence) to 20 (complete incontinence). RESULTS: There were 100 patients who had an overlapping sphincteroplasty; complete follow-up information was obtained for 77 patients at a median of 24 (range, 2-96) months. The median age was 47 (range, 25-80) years and they had a median duration of incontinence of four (range, 0.1-39) ears. Prior sphincteroplasty had been performed in 30 patients with a median of one (range, 1-7) operations. Investigations performed included electromyography (n = 49), pudendal nerve terminal motor latency (n = 71), endoanal ultrasound (n = 49), and manometry (n = 67). Sixty percent of patients had improved continence and 42 (55 percent) considered their surgery to have been successful as attested to by a significant decrease in their incontinence score (from 15.1 +/- 4.5 to 4.3 +/- 4.2; P < 0.0001). Neither patient age, parity, prior sphincteroplasty, cause or duration of incontinence, extent of electromyography damage, size of the endoanal ultrasound defect, nor any manometric parameter correlated with outcome. However, 62 percent of 59 patients With bilaterally normal pudendal nerve terminal motor latencies had a successful outcome compared with only 16.7 per cent of 12 patients with unilateral or bilateral prolonged pudendal nerve terminal motor latencies (P < 0.01). CONCLUSION: Bilateral normal pudendal nerve terminal motor latencies are the only factors predictive of long-term success after overlapping sphincteroplasty.