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Cauda Equina Syndrome Disk protrusion causing central canal stenosis (Sagital MRI)
Cauda Equina Syndrome Disk protrusion causing central canal stenosis (Axial MRI)


  • Cauda equina syndrome (CES) is an uncommon but very important cause of back pain.
  • There are many other possible causes (Table 1) but the herniation, prolapse or sequestration of a large posterior lower lumbar intervertebral disc is the most common cause.2


Table 1: List of causes of CES



Herniated discs 

Large central, sequestered and extruded discs



Vertebral fractures

Vertebral Subluxation and dislocation

Penetrating injuries


Spinal stenosis

Degenerative narrowing and compression of cauda



Malignant and primary bone tumours



Ankylosing spondylitis

Pagets disease



Spinal epidural abscess



Spinal epidural haematoma




Clinical Presentation


Classically it is characterised by the following “red flag” symptoms:

  • Lower back pain
  • Bilateral radicular sciatic pain into both legs
  • Saddle anaesthesia +/- genital sensory deficit
  • Bladder dysfunction
  • Bowel dysfunction
  • Sexual dysfunction


  • The above complaints describe the classic combination of symptoms patients present with.  However, there is a spectrum and every patient will not present with this classic combination.


  • Two forms of cauda equina syndrome have been described3:


1.  Incomplete CES

2.  Complete CES


  • This classification relates to the complete or incomplete involvement of urinary function and perianal sensation3.  
  • Incomplete CES presents with urinary neurogenic alternations, namely altered sensation when passing urine, loss of the desire to void and poor stream.  However, they retain control.  Saddle and genital anaesthesia is partial and incomplete3.
  • Complete CES is characterised by painless urinary retention with possible overflow incontinence.  Patients typically describe complete saddle anaesthesia3.
  • At one end of the spectrum and often with rapid onset of symptoms is complete CES.  At the other end is incomplete CES where symptoms may progress slower, but again the presentation is considerably variable and once the diagnosis has been questioned then appropriate action should be taken3.



Clinical Examination



  • There is usually nothing to see on inspection.



  • Again there is usually nothing to feel on palpation.
  • There may be pain over the lower back associated with intervertebral disc herniation but this is highly variable.


Move and neurological assessment

  • All patients should have a thorough neurological examination of the lower limbs and perineum.
  • The examination findings should be clearly documented as this will aid in the later management decisions if there is progression of symptoms or signs.


Management & Investigations

  • Low back pain accompanied with any red flag signs for CES should prompt the ringing of alarm bells for all doctors.
  • Following a full clinical assessment Immediate action must be taken including:



1.      Referral to A&E for attention of orthopaedic / neurosurgical on-call specialist registrar.

2.      Prompt magnetic resonance scanning of the spine (MRI) to confirm the diagnosis.

3.      Referral to appropriate regional specialist orthopaedic or neurosurgical unit for discussion and consideration for emergency or urgent decompression.




  • Prompt diagnosis, referral and investigation followed by appropriate surgical decompression is essential to achieve best practice.
  • Details of the surgical treatment of CES is beyond the scope of this summary.




  • If managed inappropriately the consequences of CES can be devastating.
  • It has been shown that the “Die is cast within the first 4-6 hours of a complete severe CES4.
  • There is a very small window of opportunity to prevent a poor outcome and therefore minor delays in management will not influence the final outcome.4
  • Even though it is very rare, it does account for a disproportionate number of medicolegal cases.  The major causes for delay and patient dissatisfaction are:3


Patient delay in seeking advice

General practitioners not recognizing the urgency of “red flag” symptoms

Junior accident & emergency staff not recognizing the condition and not calling a senior colleague

Hospital delays:

-          admission

-          Arranging an MRI

-          Referral to specialist surgical unit for decompression


Failure to warn patients of persistent neurological symptoms

Deficiencies in aftercare and rehabilitation

*  Reprinted with permission from Gardner et al (2009).


  1. Benzal E.  Spine Surgery:  Techniques, Complications, Avoidance and Management.  Churchill & Livingstone, New York.  2004.
  2. Lieberman JR.  American Association of Orthopaedic Surgery: Comprehensive Orthopaedic Review.  2009.
  3. Gardner A, Morley T.  Cauda equina syndrome.  Medical Protection Society Case Book.  2009; 17(3): 11-14.
  4. Gleave JR, MacFarlane R.  Cauda equina syndrome: what is the relationship between timing of surgery and outcome?.  British Journal of Neurosurgery.  2002.: 6(4): 325-328.