Pudendal Neuropathy Caused by Deep-Layer Penetration of the Sacrotuberous Ligament with Associated Venous Engorgement: A Surgical Case Report

In this report, we describe a rare case of pudendal neuropathy caused by deep-layer penetration of the sacrotuberous ligament (STL), accompanied by perineural venous engorgement, and emphasize its diagnostic and surgical implications.The patient was a 65-year-old man who presented with a 15-year history of left-sided perineal and testicular pain that was markedly exacerbated by sitting and partially relieved by standing or lying down.Pelvic magnetic resonance imaging (MRI) demonstrated asymmetry of the left pudendal nerve, with prominent perineural venous engorgement adjacent to the STL.Conservative treatment failed to provide adequate symptom relief; therefore, transgluteal pudendal nerve decompression was performed.Intraoperatively, the pudendal nerve was found to penetrate the deep layer of the STL and was tightly constricted at the penetration site, with marked venous engorgement.Layer-by-layer release of the deep STL achieved complete neural decompression, followed by gradual collapse of the engorged veins.Postoperatively, the patient experienced immediate and sustained pain relief, with improved tolerance for sitting.Follow-up MRI demonstrated resolution of the venous engorgement and normalization of the perineural soft-tissue signal.In summary, deep-layer penetration of the pudendal nerve through the STL, with associated venous congestion, is rare but clinically significant in pudendal neuropathy.Recognition of this anatomical variant and careful assessment of perineural venous engorgement on MRI may improve diagnostic accuracy and inform layer-by-layer surgical decompression in patients with refractory pudendal neuralgia.