Cadaveric Insights into Pudendal Nerve Variations for Sacrospinous Ligament Fixation: A Case Series

The proximity of the pudendal nerve to the sacrospinous ligaments (SSLs) can lead to serious complications during sacrospinous ligament fixation (SSLF). This case series is aimed at providing an overview of the anatomy of the pudendal nerve, including insights from cadaver dissections and discussions on rare variations observed during these dissections.

Dissections were conducted on five female cadavers using a posterior gluteal approach on both sides. The course, morphometric features and variations in the branches of the pudendal nerve were assessed at the level of the SSL and within the pudendal canal.

The number of pudendal trunks cranial to the SSL ranged from one to three, with double trunks being the most common (70%). In 2 out of 10 (20%) sides inferior rectal nerves (IRNs) pierced through the SSL. In Case 1, IRNs pierced the SSL bilaterally before entering the pudendal canal and exiting at distances of 23.81 mm and 41.18 mm from the ischial spine on the right and left sides respectively. In Case 2, nerves with a width of 2.12 mm and 2.49 mm pierced the SSL and joined the IRN, piercing the SSL at 13.38 mm and 12.55 medial to the ischial spine and 16.80 mm and 19.32 mm lateral to the sacrum, on the left and right sides respectively. In 60% of cases, the IRN entered the pudendal canal, exiting at a median distance of 21.25 mm from the ischial spine.

We identified significant variations in the number of trunks and branching patterns of the pudendal nerve around the SSL and the course of the IRN caudal to the SSL. We documented IRNs or nerves joining the IRNs piercing the SSL. Identifying these variations is crucial for surgeons to minimize the risk of pudendal nerve injury during SSLF.