Is scan-negative cauda equina syndrome a functional neurological disorder? A pilot study

Diagnosis of cauda equina syndrome in the emergency department

Cauda equina syndrome (CES) is a spinal emergency that can be challenging to identify from among the many patients presenting to EDs with low back and/or radicular leg pain. This article presents a practical guide to the assessment and early management of patients with suspected CES as well as an up-to-date review of the most important studies in this area that should inform clinical practice in the ED.

'Scan-negative' cauda equina syndrome: what to do when there is no neurosurgical cause

Suspected cauda equina syndrome is a common presentation in emergency departments, but most patients (≥70%) have no cauda equina compression on imaging. As neurologists become more involved with 'front door' neurology, referral rates of patients with these symptoms are increasing. A small proportion of patients without structural pathology have other neurological causes: we discuss the differential diagnosis and how to recognise these. New data on the clinical features of patients with 'scan-negative' cauda equina syndrome suggest that the symptoms are usually triggered by acute pain (with or without root impingement) causing changes in brain-bladder feedback in vulnerable individuals, exacerbated by medication and anxiety, and commonly presenting with features of functional neurological disorder.

Long-term mental wellbeing and functioning after surgery for cauda equina syndrome

Introduction

Cauda Equina Syndrome (CES) can cause persisting life-changing dysfunction. There is scarce literature regarding the long-term assessment of CES symptoms, and rarer still is the impact of these symptoms on mental wellbeing investigated. This study assessed the long-term patient reported mental wellbeing outcomes of post-operative CES patients.

Methods

Patients who underwent surgery for CES between August 2013 and November 2014 were identified using an ethically approved database. They then completed validated questionnaires over the telephone assessing their mental and physical functioning (Short-Form 12 Questionnaire), generating the Physical Component Summary (PCS) and Mental Component Summary (MCS). Bladder, bowel and sexual function were also assessed using validated questionnaires. MCS scores were compared to both the Scottish mean and previously published cut-offs indicating patients at risk of depression. Correlations of MCS with bladder, bowel, sexual and physical dysfunction were examined and multifactorial regression to predict MCS from these variables analysed. Independent t-tests assessed the mean difference in MCS between patients presenting with incomplete CES (CES-I) and CES with retention (CES-R) and between those with radiologically confirmed and impending CES.

Results

Forty-six participants with a mean follow-up time of 43 months completed the study. The mean (±SD) MCS was 49 (±11.8) with 22% demonstrating poor mental health related quality of life in comparison to the Scottish mean. Overall, 37% had scores consistent with being at risk for depression with in the last 30 days, and 45% within the last 12 months. MCS was significantly correlated with Urinary Symptoms Profile (USP) score (-0.608), NBDS score (-0.556), ASEX score (-0.349) and PCS score (0.413) with worse bladder, bowel, sexual and physical dysfunction associated with worse MCS score. Multifactorial regression analysis demonstrated both urinary (USP score p = 0.031) and bowel function (NBDS score p = 0.009) to be significant predictive variables of mental health related quality of life. There were no significant mean differences in MCS between those presenting with CES-I and CES-R or those with radiologically complete and impending CES.

Discussion

This study demonstrates a high frequency of being at risk for depression in patients with CES and identifies outcome measures (physical, sexual and more so bladder and bowel dysfunction) associated with poorer mental wellbeing. Our large cohort and long follow-up highlight that CES patients should be considered at risk of depression, and the need to consider mental health outcomes following CES surgery.

Suspected cauda equina syndrome: no reduction in investigation, referral and treatment during the COVID-19 pandemic

INTRODUCTION

Compression of the cauda equina can lead to bladder, bowel and sexual dysfunction with lower limb pain, numbness and weakness. Urgent surgical decompression aims to prevent progressive neurological deficit. Symptoms of cauda equina syndrome (CES), such as back pain, sciatica and bladder dysfunction are common in the population, but the majority of those investigated do not have radiological cauda equina compression. However, a missed diagnosis can have significant medical, social and legal consequences. We investigated the effect of the COVID-19 pandemic on presentation and management of suspected CES.

METHODS

This retrospective cohort study analysed referral, investigation and treatment of CES in a regional neurosurgical centre during the initial COVID-19 surge between March and May 2020 compared with March to May 2019.

RESULTS

Referrals for suspected CES were similar during the COVID-19 pandemic (n = 275) compared with 2019 (n = 261, p = 0.596) despite a significant (19%) decrease in total emergency neurosurgical referrals (1248 in 2020 vs 1544 in 2019, p < 0.001). Nineteen (7%) of the suspected CES referrals underwent decompression in 2020, similar to 16 (6%) in 2019 (p = 0.867). There were no differences in outcomes or complications and no evidence of delays in presentation or treatment.

CONCLUSIONS

Unlike other emergency neurosurgical conditions, the number of referrals for suspected CES and the percentage of referrals with radiological cauda equina compression were unchanged during the COVID-19 pandemic. The persistence of CES referrals when many people stayed away from hospital highlights the distress and worry caused by suspected CES and its symptoms to both patients and healthcare providers.

A practical review of functional neurological disorder (FND) for the general physician

We present a practical overview of functional neurological disorder (FND), its epidemiology, assessment and diagnosis, diagnostic pitfalls, treatment, aetiology and mechanism. We present an update on functional limb weakness, tremor, dystonia and other abnormal movements, dissociative seizures, functional cognitive symptoms and urinary retention, and 'scan-negative' cauda equina syndrome. The diagnosis of FND should rest on clear positive evidence, typically from a combination of physical signs on examination or the nature of seizures. In treatment of FND, clear communication of the diagnosis and the involvement of the multidisciplinary team is beneficial. We recommend that patients with FND are referred to specialists with expertise in neurological diagnosis. FND is a common presentation in emergency and acute medical settings and there are many practical elements to making a positive diagnosis and communication which are useful for all physicians to be familiar with.

Scan-Negative Cauda Equina Syndrome: A Prospective Cohort Study

OBJECTIVE

To describe clinical features relevant to diagnosis, mechanism, and etiology in patients with "scan-negative" cauda equina syndrome (CES).

METHODS

We carried out a prospective study of consecutive patients presenting with the clinical features of CES to a regional neurosurgery center comprising semi-structured interview and questionnaires investigating presenting symptoms, neurologic examination, psychiatric and functional disorder comorbidity, bladder/bowel/sexual function, distress, and disability.

RESULTS

A total of 198 patients presented consecutively over 28 months. A total of 47 were diagnosed with scan-positive CES (mean age 48 years, 43% female). A total of 76 mixed category patients had nerve root compression/displacement without CES compression (mean age 46 years, 71% female) and 61 patients had scan-negative CES (mean age 40 years, 77% female). An alternative neurologic cause of CES emerged in 14/198 patients during admission and 4/151 patients with mean duration 25 months follow-up. Patients with scan-negative CES had more positive clinical signs of a functional neurologic disorder (11% scan-positive CES vs 34% mixed and 68% scan-negative, p < 0.0001), were more likely to describe their current back pain as worst ever (41% vs 46% and 70%, p = 0.005), and were more likely to have symptoms of a panic attack at onset (37% vs 57% and 70%, p = 0.001). Patients with scan-positive CES were more likely to have reduced/absent bilateral ankle jerks (78% vs 30% and 12%, p < 0.0001). There was no significant difference between groups in the frequency of reduced anal tone and urinary retention.

CONCLUSION

The first well-phenotyped, prospective study of scan-negative CES supports a model in which acute pain, medication, and mechanisms overlapping with functional neurologic disorders may be relevant.