postheadericon ISCHIAL SPINE AND PUDENDAL NERVE ENTRAPMENT – Pain.Medicine.and.Management.Just.the.Facts

• Pudendal nerve entrapment causes neuropathic pain. • In men with PNE, aberrant development and subsequent malpositioning of the ischial spine appear to be associated with athletic activities during their youth. The changes occur during the period of development and ossification of the spinous process of the ischium. • PNE can cause chronic perineal pain. Patients with PNE typically present with pain in the penis, scrotum, labia, perineum, or anorectal region that is exacerbated by sitting, relieved by standing, and absent when recumbent or when sitting on a toilet seat. • In PNE, the pudendal nerve is trapped between the sacrotuberous and sacrospinous ligaments and may engage the falciform process of the ST ligament.40,41 • Stretching of the pudendal nerve from chronic constipation causes neuropathy. • Normal vaginal delivery causes measurable neuropathy that lasts approximately 3 months.42 • The striking common feature in all patients is that flexion activities of the hip induce or exacerbate urogenital pain, CPP, or prostatitis-like pain.43 • Attention must be paid to the transverse diameter of the ST and SP ligaments that compress the pudendal nerve; the dimensions of the greater sciatic notch correlated with age, weight, and body habitus; the cross-sectional area of the greater sciatic notch and the piriformis muscle; and sequential pelvic x-rays in youthful and maturing athletes to measure changes in position and appearance of the ischial spine. • The primary hypothesis about the etiology is that hypertrophy of the muscles of the pelvic floor during years of youthful athleticism causes elongation and posterior remodeling of the ischial spine. The SSp ligament then rotates, causing the ST and SSp ligaments to overlap. The ligaments act like a lobster claw, 29 • PELVIC PAIN 161 crushing the pudendal nerve as it traverses the interligamentous space. In addition, in this position the pudendal nerve travels a longer course because it is posterior or dorsal to the SSp ligament. In this course it may stretch over the SSp ligament or the ischial spine during squatting, sitting, or rising from a seated position. We surmise that the gluteus muscle, which is intimately attached to the ST ligament, exerts a shearing effect as it extends the hip while the pelvic floor is forced inferiorly during the Valsalva maneuver. • Pudendal canal decompression leads to pain relief in 70–86% of patients and to improved associated urinary and fecal incontinence in 65–82%.44

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