Magnetic Resonance Imaging Evaluation of Neuropathic Pelvic Pain: What to Look for and Where

Purpose or Learning Objective:

1. Understand pelvic neuroanatomy and adjacent soft tissue involved in pelvic pain.

2. Describe the role of high-resolution magnetic resonance neurography to assess pelvic nerve pathways and the causes of neuropathic pain.

3. Identify causes of pudendal neuralgia and neuropathies affecting the iliohypogastric, ilioinguinal, genitofemoral, and posterior femoral cutaneous nerves.

Methods or Background: Pelvic pain syndromes are common and often involve neuropathic components; pudendal neuralgia is the most recognized. However, other nerves from the sacral and lumbar plexus, the iliohypogastric, ilioinguinal, genitofemoral, and branches of the posterior femoral cutaneous nerve may also contribute to neuropathic pelvic and genital pain. Diagnosis is challenging due to complex neuroanatomy and overlapping etiologies. Magnetic resonance neurography helps assess affected nerves and musculoskeletal structures, with emerging sequences improving vascular suppression and nerve visualization.

Results or Findings: Pudendal neuralgia: Neuropathic perineal pain (burning, numbness, allodynia), worsened by sitting on soft surfaces.

• Neuroanatomy: Pudendal nerve (S2–S4) through Alcock's canal, innervating the perineum and pelvic floor.

• Entrapment and causes: Compression at Alcock's canal or sacrospinous/sacrotuberous ligaments (Nantes criteria) due to trauma, surgery, or chronic pressure.

• Magnetic resonance findings: Nerve thickening, signal changes, and muscle denervation.

Inferior cluneal neuralgia: Neuropathic pain in the inferolateral buttock and lateral perineal region, worsened by sitting on hard surfaces.

• Neuroanatomy: Perineal branches and inferior cluneal nerve from the posterior femoral cutaneous nerve (S1–S3).

• Entrapment and causes: Deep subgluteal syndrome, hamstring injuries, peri-ischial pathology.

• Magnetic resonance findings: Nerve thickening, edema, or fibrosis.

Border nerve pain syndrome: Neuropathic pain in the lower abdomen, groin, or proximal thigh extending to the anterior genital area.

• Neuroanatomy: Iliohypogastric, ilioinguinal, and genitofemoral nerves from the lumbar plexus.

• Entrapment and causes: Compression from spinal pathology, surgery (hernia repair, gynecologic procedures), or scarring.

• Magnetic resonance findings: Nerve signal changes, fibrosis.

Conclusion: Magnetic resonance neurography, with specialized morphological and functional sequences, is a valuable tool for diagnosing neuropathic pelvic pain. However, accurate interpretation requires a thorough understanding of pelvic neuroanatomy, entrapment sites, and underlying causes.

Publication History

Article published online:
02 June 2025