Assessment and early investigation of cauda equina syndrome- a systematic review of existing international guidelines and summary of the current evidence

Key Points

1. Cauda Equina Syndrome is an emergency needing immediate referral for correction.
2. An urgent MRI is necessary when the red flags are present.
3. Delayed MRI delays the diagnosis and correction which can lead to long term problems, especially with bowel and bladder function.

BACKGROUND & OBJECTIVE

Cauda Equina Syndrome (CES) is a clinical emergency caused by disc herniation, compression from degenerative changes, tumors, bone fragments, or from infections. An MRI is the gold standard for definitive diagnoses. Clinical signs and symptoms include bilateral radicular pain, perineal sensory disturbance, or bowel or bladder dysfunction (sudden onset of incontinence, retention, or pain) (1). Clinical screening alone is not sufficient for the diagnosis which supports the need for an urgent MRI (2).

The authors completed a systematic review on CES to create an accessible summary of current information in order to facilitate more consistent screening and timely referrals to decrease the number of missed diagnoses which lead to significant long-term burden (3).

Cauda Equina Syndrome is a clinical emergency caused by disc herniation, compression from degenerative changes, tumors, bone fragments, or from infections.

Clinicians must screen for cauda equina syndrome, beyond standard red flag questions, we have a good tool in the Oswestry Low Back Pain Disability Questionnaire that asks about sexual dysfunction.

METHODS

In this systematic review, the authors excluded papers written before 2000 as MRI screening was not sufficiently available before 2000.

RESULTS

• Nine articles were included in the review from the original 307.

• An urgent MRI was recommended by all the papers when red flags are present. Urgent is defined as one hour and as four hours in the two papers that identified a time frame.

Red flags across all nine papers include:

• Peri-anal, perinea, or saddle sensory disturbance

• Sudden onset bladder or bowel dysfunction

• Radicular/sciatic pain

• Motor weakness

• Sexual dysfunction

A stratification of symptoms is suggested by Todd (2):

• CES-S (suspicious/suspected): Urgent MRI at earliest possible time

• CES-I (incomplete i.e. signs but no urinary retention): Urgent MRI, highest likelihood of surgical referral.

• CES-R (with retention): Urgent MRI, highest likelihood of surgical referral.

Sexual dysfunction is an important red flag, especially when in the presence of bowel or bladder dysfunction (4).

LIMITATIONS

• Some of the recommended screening assessments are not routinely performed by physiotherapists (i.e. digital rectal exam).

• Depending on the jurisdiction, physiotherapists may be unable to order urgent MRI scans.

• These findings are not applicable to pediatric populations.

CLINICAL IMPLICATIONS

While there is no consensus on the time to MRI there is consensus that urgent means the same day. This is a problem in health systems with poor access due to availability of the MRI or due to denial by 3rd party payers. The individual is in danger of significant harm to their peripheral nervous system, to their bowel and bladder function, or to sexual function. This is not an age-related problem, and the urgency is the same regardless of the age or location of the individual.

Functionally, this means that clinicians must screen for CES. Beyond standard Red Flag questions, we have a good tool in the Oswestry Low Back Pain Disability Questionnaire that asks about sexual dysfunction (5). In conjunction with sudden changes in bowel or bladder function this is a reason for urgent referral. The Oswestry was revised in 2001 to eliminate the sex question for the comfort of the researchers and clinicians in order to avoid asking about sex (6).

This revision should be removed from clinical practice as it diminishes the ability to screen for CES or referral for pelvic health physiotherapy as sex should never hurt. The argument is made that sex is a challenging subject, and while that is true, it is also an activity of daily living and sudden changes in sexual function may be an indicator of urgent medical need and should not be ignored for sensitivities. We have a responsibility as clinicians to address the urgent needs of our patients and that requires that we ask sensitive questions as appropriate.

+STUDY REFERENCE

Hennessy O, Devitt A, Synnot K, Timlin M (2025) 'Assessment and early investigation of cauda equina syndrome- A systematic review of existing international guidelines and summary of the current evidence', European Spine Journal (Preprint).

SUPPORTING REFERENCE

1. Mustafa, M.A. et al. (2023) ‘Definition and surgical timing in cauda equina syndrome–an updated systematic review’, PLOS ONE, 18(5).
2. Todd, N.V. (2005) ‘Cauda equina syndrome: The timing of surgery probably does influence outcome’, British Journal of Neurosurgery, 19(4), pp. 301-306.
3. Todd, N.V. (2015) ‘Cauda equina syndrome’, The Bone & Joint Journal, 97-B(10), pp. 1390–1394.
4. Todd, N.V. (2005) ‘Cauda equina syndrome: The timing of surgery probably does influence outcome’, British Journal of Neurosurgery, 19(4), pp. 301-306.
5. Yates, M. and Shastri-Hurst, N. (2017) ‘The oswestry disability index’, Occupational Medicine, 67(3), pp. 241–242.
6. Oswestry disability index (no date) Shirley Ryan AbilityLab.