Pudendal Nerve Entrapment Syndrome

Pudendal neuralgia caused by pudendal nerve entrapment is a chronic and often severely disabling neuropathic pain syndrome. The condition manifests within the sensory distribution of the pudendal nerve and affects both male and female patients. The most characteristic symptom, reported in over 50% of cases, is perineal pain exacerbated by sitting and relieved by standing or lying. The syndrome is frequently misdiagnosed or underdiagnosed and often inappropriately treated, resulting in delayed initiation of appropriate management and substantial negative impact on quality of life. Chronic pain associated with pudendal nerve entrapment imposes significant mental and economic burdens. These factors warrant careful consideration during clinical assessment and therapeutic planning. The pudendal nerve arises from the ventral rami of the S2, S3, and S4 roots of the sacral plexus. This nerve carries sensory, motor, and autonomic fibers. Injury to the pudendal nerve primarily produces sensory deficits. The nerve initially courses between the piriformis and coccygeus muscles, exiting the pelvic cavity through the greater sciatic foramen, ventral to the sacrotuberous ligament. This neural structure then passes medial to and beneath the sacrospinous ligament at the level of the ischial spine before reentering the pelvic cavity through the greater sciatic foramen. The pudendal nerve continues within the pudendal canal, also termed the "Alcock canal." The terminal branches— the inferior rectal and perineal branches and the dorsal sensory nerve of the penis or clitoris—terminate in the ischioanal fossa. Case reports have documented anatomical variability of the pudendal nerve. For detailed anatomical information, refer to the companion StatPearls reference "Anatomy, Abdomen and Pelvis, Pudendal Nerve." Pudendal nerve entrapment syndromes are classified into 4 types according to the anatomical site of nerve compression (see . Key Landmarks for Pudendal Nerve Entrapment). Type I involves entrapment below the piriformis muscle as the pudendal nerve exits the greater sciatic notch and is frequently associated with piriformis muscle spasm. Type II, the most common form, occurs at the level of the ischial spine and the entrance of the lesser sciatic notch, where the nerve passes between the sacrospinous and sacrotuberous ligaments. Type III is characterized by entrapment at the entrance of the Alcock canal, often in association with obturator internus muscle spasm. Type IV represents distal entrapment of the pudendal nerve’s terminal divisions.