Tiny Tips – Cauda Equina Syndrome

In Medical Concepts, Tiny Tips by Mike Craig2 Comments

Cauda Equina Syndrome (CES) is a collection of signs and symptoms resulting from compression of neural elements at the cauda equina.  Although CES has no universal definition, the most commonly cited clinical presentation involves severe lower back pain, bladder dysfunction, and sensory deficits in the sacral nerve root distribution. Associated symptoms can include radicular leg pain, lower extremity weakness, and erectile dysfunction.

A recent review explores this variation in definitions and the diagnostic value of individual symptoms. The most common causes of CES include massive disc herniation (45% of cases), neoplastic lesions (29%), and infection (28%).1

CES is extremely rare overall, and is thought to account for less than 1 in 2000 patients with severe back pain.2 However, this process can have devastating sequelae if missed. Without definitive management, “incomplete” CES can lead to permanent incontinence and lower extremity deficits, while “complete” CES presents having already progressed to this stage.

Cauda Equina Syndrome

Figure: Traumatic lumbar disc extrusion causing compression of the cauda equina. Case courtesy of Dr Eric F Greif, Radiopaedia.org, rID: 29674

Suspected CES warrants an urgent workup. After a detailed neurological exam of the lower extremities, including full sensory exam of the sacral segments and digital rectal exam, bladder function should be assessed with post-void residual or with urinary catheterization. Painless urinary retention (generally considered a post-void residual volume of >300 mL) has a 90% sensitivity for CES3, although volumes encountered are commonly lower. An urgent MRI (within 1-2 hours) and a neurosurgical consultation should be sought if there is evidence of:

  • urinary retention (+/- fecal incontinence) AND
  • sensory changes
  • +/- other associated symptoms above,

If CES confirmed, urgent surgical decompression (within 36h, or sooner for incomplete CES) may need to be performed.2

An easy way to recall the presentation of CES is using the mnemonic:

Can’t Pee
Extreme pain
Sensation changes

Although exact symptoms and exam findings will depend on the location of the compressive lesion, these three features are considered a hallmark of CES.

This post was copyedited by Michael Bravo (@bravbro). 


Fraser S, Roberts L, Murphy E. Cauda equina syndrome: a literature review of its definition and clinical presentation. Arch Phys Med Rehabil. 2009;90(11):1964-1968. [PubMed]
Lavy C, James A, Wilson-MacDonald J, Fairbank J. Cauda equina syndrome. BMJ. 2009;338:b936. [PubMed]
Greenberg M. Handbook of Neurosurgery. Thieme; 2010.

Reviewing with the Staff

This is a great tip for learners to have to help them remember what to screen for when discussing symptoms with back pain patients. Not only is this is a useful aid for scaffolding one’s history taking and physical examination (i.e. what to look for and check), it may also be useful in helping learners to remember what safe discharge instructions for back pain patients looks like.

I cannot help but emphasize one how important it is to realize that it is URINARY RETENTION and FECAL INCONTINENCE that are hallmarks of this syndrome. For further reading that you might assign learners, there is great summary of these in depth can be found at Medscape.

Teresa Chan

Mike Craig

Mike is a graduate of Dalhousie Medicine, and an incoming PGY-1 in Neurosurgery at the University of British Columbia.

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