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  Nerve Pain       Pudendal Neuralgia      
 
 
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Definition
  • Pudendal neuralgia (also known as Pudendal Canal Syndrome, Alcock Canal Syndrome, and Pudendal Nerve Entrapment, PNE) is a form of nerve pain (neuropathy, neuritis) where the symptoms are perceived to be in the pelvis / pelvic / perineal region (genitals, perianal).
  • The pelvic pain is worsened by sitting and lying, and can include prickling, stabbing, burning, numbness, and the sense of a foreign object in the urethra, penis or vagina, and rectum. In addition to pain, sexual dysfunction, impotence, faecal and urinary incontinence can be a problem.

Anatomy

  • The pudendal nerve is made up of branches from the anterior sacral nerve roots (S2, S3, S4) and sympathetic fibres from the lower sympathetic chain.
  • These nerves join together to form a single nerve about 1 cm behind the ischial spine. The nerve leaves the pelvis by passing through the greater sciatic foramen just below the piriformis muscle.
  • It then crosses behind the attachment point of the sacrospinous ligament to the ischial spine, and the re-enters the pelvis through the lesser sciatic foramen.
  • It then runs forward on the inner surface of the pelvis, in the pudendal canal (also known as Alcock's Canal) together with the internal pudendal artery.
  • The pudendal nerve has 3 branches, each supplying different parts of the perineum:-
    1. Inferior anal branch - supplies the external anal sphincter and perianal skin
    2. Perineal branch - supplies labial (or scrotal) skin, pelvic floor muscles, and erectile functions in the clitoris (or penis).
    3. Dorsal nerve of the clitoris (or penis) - supplies sensation and erectile functions to these organs and also the urethra.

Causes

  • Obstetric Neuropathy - pelvic nerve injury can occur due to damage caused by the presenting part of the baby or the delivery forceps - may affect the pudendal, obturator (inner thigh) and sciatic nerves (leg below the knee).
  • Pudendal Neuropathy - sacral nerve (S2, S3, S4) invasion by rectal and metastatic bone tumours can cause pain, numbness and weakness in the areas supplied by the pudendal and sciatic nerves.
  • Pudendal Neuralgia - commonest presentation - injury to the pudendal nerve in the pelvis can be caused by excessive cycling on a narrow saddle, horse riding, chronic constipation, previous pelvic surgery, pelvic fractures and direct blunt trauma (straddle injury).

Diagnosis

  • Signs and symptoms of neuralgia in the pudendal nerve territory - neuralgic type pain associated with tingling, numbness, and allodynia (vibrational and thermal)
  • Pudendal neuralgia usually presents with symptoms on one side only, but may involve both sides at a later date. Pudendal neuropathy is frequently bilateral
  • Examination often confirms loss of pin prick sensation on the affected side, allodynia, and tenderness to palpation around the ischial spine - may need a rectal or vaginal examination to find it
  • The outcome of a diagnostic pudendal nerve block can be confirmatory

Differential Diagnosis

Investigations

  • MRI - helps to eliminate prolapsed discs and pelvic tumours but does not show pudendal entrapment
  • EMG - ? trans-vaginal
  • Perineocaliper measurements - Perineal descent of greater than 2cm during straining has been shown to increase the risk of pudendal neuralgia and other pelvic complaints such as dyschesia (difficulty with defaecation), faecal incontinence, urinary frequency / urgency, dyspareunia (pain during sex), cystocele (vaginal prolapse), and rectocele (rectal prolapse) - see www.perineology.com
Treatment
  • Self Care
    • Avoid direct pressure to the ischial tuberosities
    • Avoid activities which aggravate the pain (cycling, hip flexion etc.)
  • Pain Relief Drugs
  • Injections
    • Pudendal nerve block - LA / steroid injection either by manual palpation, CT or ultrasound guidance.
  • Physiotherapy
    • Pelvic floor training can help to reduce excessive perineal descent, and to help reduce the symptoms of pudendal neuralgia
  • Surgery
  • Neuromodulation
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