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In patients with low back pain, which symptoms and signs are predictive of acute cauda equina syndrome (CES) and which should necessitate emergency investigation with MRI (<6 hours) to rule out CES?

Three Part Question

In [adults over 18 imaged due to suspected cauda equina syndrome] which [symptoms and signs] are [predictive of acute cauda equina syndrome (CES) and which should necessitate emergency investigation with MRI (<6 hours) to rule out CES]?

Clinical Scenario

A 55-year-old woman presents with back pain and bilateral leg weakness. What would you do next?

Search Strategy

Databases used Medline, Embase, Cinahl and Amed on the world wide web. 2020 – June 2022
Year 2020 – present due to systematic review in 2020 with no conclusive findings.

[exp cauda equina syndrome] AND [assess* OR diag* OR exam* OR invest* OR predict* OR present* OR signs* OR symptoms* OR clinical*] LIMIT to human and english language

Search Outcome

10 papers were found but only 5 were relevant to the question.

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
Angus M et al.
313 patients aged between 19–79 were included. Cauda scale (TCS) was assessed for clinical validation using the retrospective data of 313 patients undergoing a lumbar spine MR scan due to the clinical suspicion of CES. TCS divides symptoms and signs into three domains – perineal sensation (S), anal tone and squeeze (T) and bladder (B).Retrospective cohort studyTo validate the cauda scale (TCS) in an external population. It is not a helpful tool in its current state for early identification of CES in the ED and can therefore not be utilised in the decision-making process regarding the timing of MRI imaging in cases of suspected CESData from a single large tertiary referral spinal surgery centre. Therefore, decision-making may vary in services with clinicians working in non-specialist units.
Alshahwani AA et al.
Total of 532 participants from 5 studies. Only papers which included numerical values of post-void urine volume were measured. Systematic Review “Is bladder scan a suitable tool for screening cauda equina syndrome complementary to clinical examination?” and “What would be the expected significant post-void residual (PVR) volume to proceed to the MRI scan?”Measuring the post-void urine volume using a bladder scan is a useful tool in the diagnosis of CES. There is a significant correlation between the PVR volume of more than 200 ml and higher sensitivity and specificity.All studies are retrospective except for two and there are no randomized controlled trials.
Angus M et al.
111 patients that were over 18 and had standard imaging (MR lumbar spine) due to a clinical suspicion of CEC.Retrospective case note reviewEvaluation of the accuracy of individual clinical features with atraumatic back pain The most frequent self-reported symptom was bilateral leg pain. The most frequent objective examination findings were dermatomal loss of sensation and bilateral absent ankle or ankle and knee jerks. No identifiable benefits to DRE and limited utility for bladder scanning. Key examination findings were not recorded for every participant. Participants with atraumatic back pain who did not receive a scan were not followed up or included.
Lopez CC et al.
Patients who presented via an established atraumatic back pain pathway, between January 2015 and December 2018. 1005 patients were included with 117 MRI positive CES patients. Retrospective observational study. Evaluation of the diagnostic value of anal tone and perianal sensation assessment in patients with suspected CES.Reduced anal tone has no demonstrable diagnostic value for those with suspected CES, either in itself or in combination with other clinical findingsVariability of clinical assessment and subjective documentation. A proportion of patients were under 18 years old.
Tabrah J et al.
Primary diagnostic accuracy studies of adults (16 years or older) presenting to secondary care or tertiary centres) with acute CES, in which DRE was the index test and lumbar MRI was the reference standard. 5 retrospective observation studies and one prospective study was included. Systematic Review Diagnostic accuracy of DRE of anal tone, squeeze, sensation and reflexesThere is moderate quality evidence that anal tone testing with digital rectal examination (DRE) has low diagnostic accuracy for detecting CEC in people presenting with CES. It carries a high risk of false reassurance with the potential for diagnostic and surgical delay and is not recommended in any clinical setting. Five of the six studies included in this review were retrospective, with a ‘high’ or ‘unclear’ risk of bias, but GRADE analysis found that the overall quality of evidence was largely moderate.


There is limited evidence surrounding which symptoms and signs are predictive of acute cauda equina syndrome (CES). However, there was some evidence to suggest that digital rectal exams are not an effective prognostic tool in the assessment of an adult with suspected cauda equina syndrome due to their low diagnostic accuracy and false reassurance. Further research is required to explore this link and perhaps lead to an additional best bets review.

Clinical Bottom Line

This question has not been answered due to the lack of evidence surrounding this topic.


  1. Angus M, Berg A, Carrasco R, Horner D, Leach J, Siddique I. The Cauda scale–validation for clinical practice. British journal of neurosurgery 2020; 453-456
  2. Alshahwani AA, Boktor J, Elbahi A, Banerjee P. A Systematic Review of the Value of a Bladder Scan in Cauda Equina Syndrome Diagnosis. Cureus 2021; 14441
  3. Angus M, Curtis-Lopez CM, Carrasco R, Currie V, Siddique I, Horner DE. Determination of potential risk characteristics for cauda equina compression in emergency department patients presenting with atraumatic back pain: a 4-year retrospective cohort analysis within a tert Emergency Medicine Journal 2021
  4. Lopez CC, Berg AJ, Clayton B, Siddique I, Carrasco R, Horner D, Angus M. Evaluation of the role of anal tone and perianal sensation examination in the assessment of suspected cauda equina syndrome. British Journal of Neurosurgery 2021;
  5. Tabrah J, Wilson N, Phillips D, Böhning D. Can digital rectal examination be used to detect cauda equina compression in people presenting with acute cauda equina syndrome? A systematic review and meta-analysis of diagnostic test accuracy studi Musculoskeletal Science and Practice. 2022; 102523