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cauda equina syndrome (CES)


  • an important complication of various conditions which cause low back pain (although it can occur without back pain), which requires urgent MRI to avoid delay in surgical Rx which increases risk of permanent urinary +/- faecal incontinence.
  • early recognition and treatment of CES is associated with improved outcome with respect to bladder function.
  • failure to recognise and treat this condition expediently may have outcome and medico-legal implications
  • said to account for 1% - 10% of all operated lumbar disc herniations

acute onset clinical features

  • urinary symptoms - eg. incontinence or retention
  • saddle anaesthesia
  • +/- reduced anal tone
  • +/- faecal incontinence
  • usually in a setting of acute or chronic low back pain +/- radicular pain to buttocks &/or legs
  • “complete lesions” are typically characterised by painless urinary retention with overflow incontinence.
  • “incomplete lesions” present with symptoms of impaired bladder function including urinary frequency, painful urinary retention or inability to void in past 6hrs, and/or urge incontinence, +/- muscle weakness in legs.
  • patients with incomplete CES (ie. without retention) should be Mx more emergently than those with painless retention as surgery within 24hrs onset rather than within 48hrs is likely to give better outcomes1)


  • acute urinary retention in setting of back pain (~90% sens.)
  • bilateral sciatica + urinary symptoms + perianal sensory changes (60-70% sens.)
  • urgent MRI assessment in all patients who present with new onset urinary symptoms in the context of lumbar back pain or sciatica.
    • ~40% of urgent scans fail to show structural evidence of CES as clinical findings have low specificity and some cases may be functional


  • patients with severe pain anywhere may develop urinary difficulties, presumably due to increased sympathetic tone
  • conus medullaris syndrome
    • the most distal bulbous part of the spinal cord at L1-2 is called the conus medullaris
    • aetiology is similar to that of cauda equina syndrome except the usual lumbar disk prolapses are too low to affect the cord
    • clinical features tend to overlap those of cauda equina syndrome however, neurology involving higher level dermatomes and myotomes may be affected, and reflexes are generally hyper-reflexic if UMN lesion rather than LMN lesions as in cauda equina syndrome.
  • spinal cord compression from abscess, tuberculosis (TB), haematoma or malignancy


ED Mx of suspected CES

  • is it complete or incomplete lesion:
    • post-void bladder scan to exclude urinary retention
    • is there overflow or urge incontinence?
    • check perianal sensation and anal tone
  • is there evidence of, or risk for malignancy and spinal cord compression?
  • if urinary retention then insert IDC
  • urgent MRI scan - same day!
  • d/w neurosurgeons same day!
    • the window of opportunity to surgically reduce permanent disability in imcomplete CES without urinary retention is only 24-48hrs
    • appears to be no benefit in Rx within 24hrs compared to Rx within 24-48hrs, although re-analaysis suggests some patients with incomplete CES may have further benefit in surgery under 24hrs 2)3)
    • general consensus is that surgery should be performed within 48hrs of onset but avoid overnight surgery when complication rates are likely to be higher 4)
    • patients who develop urinary retention early after disc prolapse (complete CES) are far less likely to benefit from surgery as the damage is probably irreversible within 6hrs based upon physiologic studies, and outcome studies of this group demonstrate generally poor outcomes suggesting the “die is cast” before surgery is possible
    • 75% of all CES cases will eventually have acceptable urological function and 20% of all CES patients will have a poor outcome usually with the need for ongoing treatment e.g. management of sexual dysfunction, self catheterisation, colostomy, urological and gynaecological surgery, spinal injuries rehabilitation and psycho-social support.5)
ces.txt · Last modified: 2020/01/31 02:57 by

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