Clinical Notes : Neurology

20. Cauda Equina Syndrome

  • This diagnosis has to be considered in all patients with severe back and leg pain

  • If suspected refer for an urgent (same day) MRI scan



  • Cauda Equina Syndrome (CES) is rare, but a major cause of litigation

  • It is most often caused by a lumbar disc prolapse

  • The spinal cord ends at S1, below which emerges the ‘horse’s tail of rootlets’ that supply the lower limbs plus bladder, bowel and sexual function

  • The consequences of a missed diagnosis therefore include urinary and faecal incontinence, loss of perineal sensation, sexual dysfunction and chronic back and leg pain

  • Two main types

    • CES-R for retention

    • CES-I for incomplete, with reduced urinary sensation, loss of desire to void or poor stream but no established retention or overflow

  • Both need immediate surgical referral, but CES-R is less likely to be reversible


  • Consider the diagnosis when

  • Escalating and severe low back pain

  • Do not be fooled by the patient who prefers to sit up, as the pain is often better in a sitting up position

  • Bilateral leg pain

  • Loss of perineal sensation

  • Urinary dysfunction

  • Examination

  • Neurological

  • Reflexes

  • Ankle Jerk (S1)

  • Knee Jerk (L3/4)

  • Sensation

  • Lateral foot sensation (S1)

  • Medial foot sensation and toes (L5)

  • Power

  • Extension big toe (L5),

  • Stand on tip-toes (S1)

  • SLR test

  • L4-S1 roots

  • Rectal examination may be misleading as anal tone is preserved in CES-I

  • Perianal sensation with a neuro-tip/ sharp end of a paperclip should be assessed


Red flags and safety-netting

  • Warn all patients with disc herniation about perineal/ peri anal numbness (eg when washing or wiping) and also any disturbance of normal urinary function



  • Record when symptoms and signs first started

  • Record all positive and negative signs elicited


Todd NV

Guidelines for cauda equina syndrome. Red flags and white flags. Systematic review and implications for triage.

Br J Neurosurg. 2017 Jun;31(3):336-339.



Spector LR, Madigan L, Rhyne A, Darden B, Kim D.

Cauda equina syndrome.

J Am Acad Orthop Surg. 2008 Aug;16(8):471-9.


Lavy C, James A, Wilson-MacDonald J, Fairbank J

Cauda equina syndrome.

J Am Acad Orthop Surg. 2008 Aug;16(8):471-9.



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