Intended for healthcare professionals

Practice Easily Missed?

Cauda equina syndrome

BMJ 2021; 372 doi: (Published 12 January 2021) Cite this as: BMJ 2021;372:n32
  1. Kevin Barraclough, general practitioner
  1. Hoyland House, Painswick GL6 6RD, UK
  1. k.barraclough{at}

What you need to know

  • Sciatica is pain or numbness that is usually referred below the knee (in contrast to non-radicular pain referred to the upper posterior thigh). Although bilateral sciatica is the classic “red flag” symptom for cauda equina syndrome (CES), it is present in only about 50% of cases

  • It is critical to diagnose CES before the patient becomes incontinent. Advice to return if the patient becomes incontinent is too little too late

  • Pain inhibition may cause difficulty passing urine, but patients with pain inhibition alone do not have loss or reduction in bladder or urethral sensation or perineal sensory disturbances

  • Assessment of anal tone is a poor predictor of cauda equina function, while subjective disturbance of saddle sensation is an unusual symptom that needs to be considered carefully. The accuracy of perianal sensory testing is unknown, and normal results should not be over-interpreted

A 42 year old woman presented to an out-of-hours general practitioner with a five day history of low back pain with burning pain radiating into her right foot. She had a body mass index of 39 and a 12 year history of chronic low back pain with intermittent left sided “sciatica” pain in her thigh. She had noted “tingling” in her genital area. There was no incontinence. The general practitioner considered, on examination, that anal tone and perianal sensation were normal, as were power, tone, reflexes, and sensation in the legs. The patient was treated with analgesia and given advice to seek review if she developed bilateral sciatica, became incontinent, or developed leg weakness. Three days later, she was admitted with cauda equina syndrome and underwent surgical decompression. She was left with lower limb weakness, numbness of the genitalia, loss of sexual function, and urinary and faecal incontinence.

What is cauda equina syndrome?

Cauda equina syndrome (CES) is a rare condition in which the …

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