Cauda equina syndrome—most frequent referral diagnosis to a tertiary spinal centre: a retrospective study

Introduction

Cauda equina syndrome (CES) is a rare but critical surgical emergency, occurring due to compression of the spinal cord and its associated nerves arising from L1 to L5 spinal levels (1). CES has a prevalence of 1 in 30,000–100,000 people per year and an estimated incidence of 1.5–3.4 per million people per year (2,3). In 45% of patients with CES, the most common cause is lumbar intervertebral disc herniation. Other causes include epidural abscess, spinal epidural haematoma, discitis, tumours, trauma, spinal stenosis and aortic obstruction (2,4).

CES patients typically present with a combination of clinical features as a result of multiple sacral and lumbar roots becoming impacted. Lavy et al. state that these features may include back pain, lower limb sensory change or weakness, impaired lower limb reflexes which may be unilateral or bilateral (1). However, the key diagnostic symptoms for CES, as stated by the “Standards of Care for Investigation and Management of CES 2015 Guidelines” from British Association of Spine Surgeons (BASS), are a patient presenting with back pain and/or sciatic pain with any disturbances of their bowel or bladder function and/or saddle or genital sensory disturbance or bilateral leg pain (5).

Accurate and timely diagnosis of CES is difficult yet crucial as delayed diagnosis and management can lead to severe complications, life-long disability and risks of litigation to the healthcare provider (2,6). There had previously been a lack of clarity regarding the specific diagnostic criteria for CES due to clinical examination alone being insufficient for a conclusive CES diagnosis but recent standards released in 2023 by BASS and Getting It Right First Time (GIRFT) have since attempted to mitigate this (5,7).

Magnetic resonance imaging (MRI) is the only investigation to prove or rule out a diagnosis of CES requiring surgery. This should be requested as an emergency by any clinician assessing a patient with a suspected CES. Once the diagnosis is proven by MRI, referral to the local spinal centre should be made immediately (8).

These guidelines have provided a national CES pathway, highlighting the need for an emergency MRI scan performed locally in suspected CES patients before referral to spinal services to reduce delays and unnecessary referrals. However, the realities of widespread implementation of such a protocol have been challenging as it has posed increased challenges due to resource shortages at some medium-sized district general hospitals (9).

Despite its rarity, CES has paradoxically emerged as one of the most common referral diagnoses to tertiary spinal centres, becoming a default cause for referral in patients with back pain, neuromuscular, or urogenital symptoms. This discrepancy between referral rates and the actual prevalence of CES raises concerns about potential over-referral and inefficiencies in clinical pathways (10).

In response to this influx of emergency CES referrals lacking pre-referral MRIs to our tertiary spinal centre, this study aimed to investigate whether CES referrals were disproportionate to confirmed diagnoses and referrals were being made in line with the national CES pathway by auditing previous referrals made across a predefined time period to assess the quality of referrals and their outcomes.

We aimed to identify areas for improvement in clinical practice, to reduce resource strain and ensure timely, effective care for patients with true CES requiring surgical management. We present this article in accordance with the STROBE reporting checklist (available at https://jss.amegroups.com/article/view/10.21037/jss-25-112/rc).

Methods

A retrospective review was conducted where an audit against the national CES pathway guidelines was performed at a major spinal centre in the UK.

This study was approved by the local clinical audit department. Referral data was collected from the electronic patient referral system, ReferaPatient and relevant patient notes at a tertiary spinal centre. This data was then recorded on a Microsoft Excel spreadsheet. All data were stored on secure trust servers. Statistical analysis was performed using the IBM SPSS statistics software platform.

All urgent and emergency referrals made to a tertiary spinal centre via the ReferaPatient system across 15 weeks between June to September 2023 were included. This time period was chosen as it represented the first 100 CES referrals from the start date of the study and was representative of the anecdotal observation made over a prolonged period of unnecessary referrals to CES.

True CES was defined as that which is due to spinal stenosis and requires emergency surgery. There were no borderline MRI findings and the decision for surgery was based on an MRI finding of cauda equina compression correlating with clinical presentation of CES. Those patients with a clinical CES, but no MRI-proven cauda equina compression, were not operated on as an emergency. These would be patients with only nerve root compression requiring surgery at a later date for lumbar spinal radiculopathy. Therefore, when reviewing data retrospectively, patients who had emergency surgery were identified as confirmed surgical CES.

Referrals received by the tertiary spinal centre were analysed to see how many were referred with suspected CES by looking at the examination findings and whether an MRI was performed prior to the referral and within 24 hours of the patient presenting to the referring hospital and the MRI being performed. Referrals included the examination findings as listed in Table S1 in the supplementary section. From the urgent and emergency referrals made to the tertiary spinal centre, referrals that were not suspected CES of were separated. From these suspected CES referrals, we utilised patient records to ascertain the number of patients with true CES requiring surgical management. The data abstraction was conducted independently and cross-checked by both authors.

Due to this being a retrospective study, the data were susceptible to incomplete documentation. All attempts were made to cross-reference documentation to gather all relevant data. We ensured MRI reports we did not pick up any alternative diagnosis and we did not receive any feedback from the referring hospitals regarding whether any other cause for patient’s presentation was identified.

Statistical analysis

The primary assessment criteria used for our audit were assessing the number of CES emergency referrals with an MRI performed prior to referral. Secondary assessment criteria analysed how many of these patients had an MRI at the referring hospital within 24 hours of presenting with symptoms. The required compliance was set to 100% for both outcomes.

Secondary analyses looked at the presenting symptoms of suspected CES patients against true CES patients requiring spinal surgery as well as the total number of emergency and urgent referrals versus all suspected CES referrals and true CES cases which required surgical management to the tertiary spinal centre. Chi-squared test was then used to compare the confirmed and suspected CES groups.

Ethical considerations

The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. Ethical approval and informed consent were not required, as data were collected for quality improvement and audit purposes with no direct involvement with patients.

Bias

Different levels of clinical specialists had assessed these patients at the referring hospital. Therefore, the urgency of a referral and clinical assessment may have differed. This would also reflect in the justification for referral and the indication to do an MRI scan before referral. Most of the referring hospitals do not have 24-hour access to an MRI scanner. Because these are multispecialty hospitals, there would be other patients requiring an urgent MRI.

Results

During the study period, 353 referrals were received via the electronic referring system from six local district general hospitals. Demographically, 49% of the patients were female, with a mean age of 38 years. We did not find any missed CES referrals in the study sample.

Suspected CES accounted for 102 referrals (29%). Confirmed CES was identified in 6 cases (1.7% of total referrals; 5.9% of CES referrals). Common alternative spinal diagnoses included lumbar spinal stenosis, lumbar disc prolapse, and degenerative back pain. This is demonstrated in Figure 1.

Figure 1 CES referral inclusion diagram. CES, cauda equina syndrome.

Examination findings

Examination findings were compared between confirmed CES patients requiring surgical management (n=6) and suspected CES patients (n=102). The frequency of red flag symptoms was analysed in both groups, with patients having the potential to present with multiple symptoms simultaneously. The outcomes are presented in Figure 2, with no significant difference between suspected versus confirmed CES patients.

Figure 2 Bar chart comparing examination findings frequency of red flag symptoms between confirmed vs. suspected CES. CES, cauda equina syndrome.

Referral timings

CES referral timings varied, with 43 (42.2%) being received by the tertiary spinal centre within routine working hours (08:00 to 18:00) and 59 (57.8%) being referred out of hours (18:00 to 08:00).

MRI utilisation

Of the patients who had been referred with suspected CES within working hours, 31 (72%) had an MRI performed by the referring hospital prior to making a referral. Conversely, 18 (31%) of out-of-hours CES referrals had an MRI performed prior to referral. In all, 49 (48%) of all CES referrals had an MRI performed prior to referral. Of the patients with true CES requiring surgical management, 5 (83%) had an MRI performed at the referring hospital. Forty-six (94%) patients out of the total 49 patients that had an MRI had this performed at the referring hospital within 24 hours of presenting with symptoms.

False positive cauda equina referrals and their trajectories

We reported 26 false positive CES referrals to our tertiary spinal centre. Seventeen of these referrals were of patients transferred to the tertiary spinal centre but discharged without need for surgery. In the remaining 9 referrals, 2 patients did not require outpatient department appointments at the tertiary centre, 2 patients had elective surgeries, 3 had urgent surgery on admission for radiculopathy and 2 were discharged from the outpatient department, not requiring surgery.

Discussion

CES is a rare but serious condition that requires rapid identification and intervention to prevent permanent neurological deficits, including bladder and bowel dysfunction and lower limb weakness. Given its medicolegal implications and the risk of irreversible damage, timely diagnosis and management are paramount (1,7,8). National guidelines, such as those issued by BASS and GIRFT in 2023, have aimed to standardise CES referral pathways, optimise MRI access, and reduce unnecessary delays in treatment (5,11). Our study assessed the implementation of these guidelines in a single-centre audit and compared our findings with existing literature to evaluate broader trends and ongoing challenges. We found that there was not 100% compliance with the standards assessed, which were MRI being performed prior to referral and within 24 hours of patient presenting to referring hospital with symptoms. A team meeting was held to highlight this issue and encourage the team to highlight these issues to the referring hospital whilst accepting referrals.

Our results demonstrated that, despite the presence of structured referral pathways, delays or the lack of MRIs being performed prior to referral remain a bottleneck in the diagnostic process. In particular, the finding that only 5.9% of suspected CES referrals were true CES highlights the issue of over-referral. This can also lead to clinical consequences, such as poor patient experience for an already anxious patient, as well as a fear of future CES instilled in the patient. Anecdotally, we have seen these false positive patients presenting to accident and emergency (A&E) on a few more occasions fearing they have CES. Some of these false positive referrals were found to have nerve root compression which required a nerve root injection or lumbar spinal decompression at a later date. It is also our observation that such patients who are referred via A&E are unlikely to accept conservative management and would opt for early intervention. This finding is consistent with that of the ENTICE study, which reviewed 4,000 CES referrals across 28 centres and identified significant over-triage for suspected CES due to inadequate investigations, leading to unnecessary MRI use in patients who did not require urgent surgical intervention (10). This overutilisation not only strains radiology services but also delays imaging for true CES cases, prolonging the time to surgical decompression, which is a crucial determinant of neurological recovery (12,13). Our study adds to this growing body of evidence, highlighting the need for more refined pre-MRI triage criteria that balance early detection with resource optimisation.

A recent study by Gill et al. [2024], evaluated the impact of the BASS and GIRFT guidelines implementation by auditing pre-guideline and post-guideline performance and found that the standardised referral pathways demonstrated improved MRI utilisation post-guideline implementation (14). Our findings indicate that, while protocol adherence may have improved, variability in MRI availability at the referring hospitals continues to pose challenges, particularly out-of-hours. Similar observations were made by Hussain et al. [2018], who noted that 87% of patients presenting without imaging out-of-hours experienced delayed investigation (6). Addressing this gap remains a key priority in improving CES diagnostic efficiency.

Staff availability and specialised service structure are other factors that could influence CES investigation timelines. A study examining the presence of an orthopaedic doctor in the emergency department demonstrated a significant reduction in MRI wait times from 12.5 to 8 hours, reinforcing the importance of clinician availability in expediting imaging and diagnosis (15,16). While our study did not assess staffing models directly, our findings suggest that dedicated orthopaedic teams or senior clinical decision-makers in emergency departments could streamline referral and triage processes, reducing unnecessary delays and potential litigations (17). We would strongly recommend that referring clinicians follow established guidelines from BASS and GIRFT. MRI scans should be performed prior to referral, which will reduce unnecessary strain on spinal services. Referring hospitals should invest in out-of-hours imaging facilities. Training for A&E staff and other clinicians is also highly recommended. Previous studies have failed to identify any clinical sign or cluster of signs to prove or disprove a true CES. Therefore, the recommendation is to carry out an urgent MRI scan, which is conclusive.

Despite its strengths, this study has several limitations. We only looked at results from one tertiary spinal centre, limiting experiences and geographic spread of referring centre. Its findings may not be fully generalisable across other spinal centres in different geographical locations with varying socio-economic demographics, particularly in institutions with varying MRI availability. We could also have benefited from using a longer observational time period for this study. Future studies should also investigate patient-reported outcomes following referral pathway modifications, as functional recovery from the patient’s point of view remains the ultimate measure of service efficiency and effectiveness.

Conclusions

This audit highlights the ongoing challenges in CES referral and investigation, despite improvements following the implementation of national guidelines. While structured pathways have enhanced protocol adherence and awareness, MRI access remains a key limiting factor, particularly out-of-hours. Over-triage of suspected CES cases continues to burden radiology and spinal services, necessitating refined pre-MRI triage criteria to balance sensitivity and resource allocation.

To improve CES service delivery, we recommend improving 24/7 MRI access, particularly in smaller district general hospitals, and considering workforce modifications such as having an orthopaedic doctor in emergency departments. Implementing guideline-compliant practices tailored to resource availability is essential to optimise patient outcomes and reduce medicolegal risk associated with delayed intervention.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://jss.amegroups.com/article/view/10.21037/jss-25-112/rc

Data Sharing Statement: Available at https://jss.amegroups.com/article/view/10.21037/jss-25-112/dss

Peer Review File: Available at https://jss.amegroups.com/article/view/10.21037/jss-25-112/prf

Funding: None.

Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://jss.amegroups.com/article/view/10.21037/jss-25-112/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. Ethical approval and informed consent were not required, as data were collected for quality improvement and audit purposes with no direct involvement with patients.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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