Anatomic variations of pudendal nerve within pelvis and pudendal canal: clinical applications.

OBJECTIVE: The objective of the study was to examine the anatomic variation of the pudendal nerve in the pelvis, on the dorsal surface of the sacrospinous ligament, and in the pudendal canal.

STUDY DESIGN: Detailed dissections of the pudendal nerve were performed in unembalmed female cadavers. Pelvic measurements included the distance from the origin of the pudendal nerve to the tip of ischial spine and the nerve width at its origin. The length of the pudendal canal was measured. The inferior rectal nerve was identified in the ischioanal fossa and its course documented. Lastly, the relationship of the pudendal nerve to the dorsal surface of the sacrospinous ligament was examined after transecting the lateral surface of the sacrospinous ligament. Descriptive statistics were used for data analyses and reporting.

RESULTS: Thirteen female cadavers (26 hemipelvises) were examined. A single pudendal nerve trunk was identified in 61.5% of hemipelvises. The median distance from the point of the pudendal nerve formation to the ischial spine was 27.5 mm (range, 14.5-37 mm). The width of the pudendal nerve in the pelvis was 4.5 mm (range, 2.5-6.3 mm). The length of the pudendal canal was 40.5 mm (range, 20.5-54.5 mm). The inferior rectal nerve was noted to enter the pudendal canal in 42.3% of hemipelvises; in these cases, the nerve exited the canal at a distance of 32.5 mm (range, 16-45 mm) from the ischial spine. In the remaining specimens, the inferior rectal nerve passed behind the sacrospinous ligament and entered the ischioanal fossa without entering the pudendal canal. In all specimens, the pudendal nerve was fixed by connective tissue to the dorsal surface of the sacrospinous ligament.

CONCLUSION: Great variability exists in pudendal nerve anatomy. Fixation of the pudendal nerve to the dorsal surface of the sacrospinous ligament is a consistent finding; thus, pudendal neuralgia attributed to nerve entrapment may be overestimated. The path of the inferior rectal nerve relative to the pudendal canal may have implications in the development of anorectal symptoms. Improved characterization of the pudendal nerve and its branches can help avoid intraoperative complications and enhance existing treatment modalities for pudendal neuropathy.