IntroductionDamage to the pudendal nerve can occur suddenly as a result of trauma to the pelvic region, prolonged bicycling, fractures or from falls.
- Also known as Alcock canal syndrome
- Origin: S2, S3, and S4 roots of ventral rami of sacral plexus
- Content: Sensory, motor, and autonomic fibers (however, injury causes sensory deficits more than motor)
- Courses between piriformis and coccygeus muscles
- Departs pelvic cavity through greater sciatic foramen ventral to sacrotuberous ligament
- Passes medial to and under sacrospinous ligament at ischial spine level to re-enter the pelvic cavity through lesser sciatic foramen
- Courses in the pudendal canal “Alcock canal”
- Terminal branches (three) end in ischioanal fossa:
- Inferior rectal branch
- Perineal branch
- Dorsal sensory nerve of the penis/clitoris
Pudendal nerve compression based on anatomy:The pudendal nerve entrapment syndromes subdivide into four types based on the level of compression.
- Type I – Entrapment below the piriformis muscle as the pudendal nerve exits the greater sciatic notch.
- Type II – Entrapment between sacrospinous and sacrotuberous ligaments is the most common cause of nerve entrapment.
- Type III – Entrapment in the Alcock canal.
- Type IV – Entrapment of terminal branches.
- Pelvic surgery:
- Pelvic organ prolapse (PoP) repair (M/C cause of pudendal neuralgia)
- Mid-urethral sling surgery
- Anterior colporrhaphy
- Direct trauma to buttocks/back
- Vaginal delivery
- Chronic constipation
- Excessive cycling: Chronic perineal microtrauma, which causes fibrosis in the pudendal canal and also the sacrospinous and sacrotuberous ligaments
- Prolonged sitting
- Viral infections (herpes zoster, HIV)
- Multiple sclerosis
- Diabetes mellitus
- Pain, numbness, and dysfunction in distribution of pudendal nerve (genitalia, rectum, and terminal urinary tract)
- Sexual dysfunction: Persistent arousal, dyspareunia, vulvodynia, and male impotence
- Sphincter dysfunction: Dyschezia, fecal incontinence, and urinary hesitancy
- Foreign body sensation in the anus, rectum, urethra, or vagina.
- Conservative management:
- Avoidance of painful stimulus
- Lifestyle modifications
- Physical therapy: Relaxation of pelvic floor muscles by releasing spasm and muscle lengthening
- Pharmacologic therapy: Analgesics, muscle relaxants, and anticonvulsants (including gabapentin and pregabalin)
- Pudendal nerve block: Local anesthetic/steroid infiltration
- Surgical decompression: Definitive treatment for PNE
- Approaches: Transperineal, transgluteal, transischiorectal, and laparoscopy
- Neuromodulation: Latest treatment using a peripheral nerve stimulator, which causes stimulation of the pudendal nerve in the ischioanal fossa.
- Pulsed radiofrequency: Newer neuromodulation technique and is considered safer than continuous radiofrequency ablation