New, simple approach for maximal pudendal nerve exposure: anomalies and prospects for functional reconstruction.

PURPOSE: Functional neosphincters after pudendal nerve anastomosis proved possible in animal models and may be applicable in humans, but access is a recognized problem. We report the occurrence of pudendal nerve anomalies, its implications for reconstruction, and describe a new approach for maximal exposure.
METHODS: Adult human cadavers were positioned prone and dissected via a gluteal approach. Pudendal nerve variations and physical measurements were analyzed statistically.
RESULTS: A new, simple, four-step approach (surface landmarks and exposure of gluteus maximus muscle, sacrotuberous ligament, and pudendal neurovascular bundle) permitted optimal pudendal nerve exposure in all 14 human cadavers (28 limbs). Six were males and had a mean age of 82 (range, 58-102) years. Two anomalies, Type 1 (2-trunked) and Type 2 (3-trunked), of the pudendal nerve were recognized in 30 percent of cadavers, with a left-to-right ratio of 2.5:1. Mean pudendal nerve length over the ischial spine was 23.9 (range, 19-28) mm right, 24.2 (range, 19-28) mm left (P = 0.54), but its diameter measured 5.2 mm (right) and 4.9 mm (left; P = 0.04). Mean length of pudendal nerve trunk exposed after reflection of the sacrotuberous ligament was 55 (range, 44-75) mm on either side before division into terminal branches. The number and percent frequency of inferior rectal nerve on both sides were 1 (13 percent), 2 (76 percent), and 3 (11 percent), respectively, with a mean length of 27.1 (range, 21-34) mm right and 27.9 (range, 20-33) mm left (P = 0.31).
CONCLUSION: A simple four-step approach to the pudendal nerve contributes to improved access in all cases. It facilitates reconstruction because it allows accurate nerve selection and recognition of potential anomalies that might influence functional outcome.