REVIEW ARTICLE Cauda Equina Syndrome: A Literature Review of Its Definition and Clinical Presentation Stuart Fraser, BSc, Lisa Roberts, PhD, Eve Murphy, MSc ABSTRACT. Fraser S, Roberts L, Murphy E. Cauda equina syndrome: a literature review of its definition and clinical presentation. Arch Phys Med Rehabil 2009;90:1964-8. Objective: To review the current evidence for the signs and symptoms of cauda equina syndrome (CES). Data Sources: Relevant literature sourced through Medline, Embase, and CINAHL using the key search words “cauda equina syndrome” combined with “definition,” “clinical presentation,” “signs and symptoms,” “pathology,” and “etiology.” Study Selection: Not applicable. Data Extraction: Not applicable. Data Synthesis: Three reviewers independently extracted data on CES from the literature specific to its definition, clin- ical presentation, and etiology. Of 111 articles, 105 were in- cluded for review, and relevant information on CES was syn- thesized into a framework structured as per a clinical consultation. A content analysis was then conducted using the method adopted by the Chartered Society of Physiotherapy whereby the level of consensus for each sign and symptom of CES was determined by its percentage coverage within the literature: 100% coverage equals unanimity, 75% to 99% equals consensus, 51% to 74% equals majority view, and 0% to 50% equals no consensus. This enabled the frequency of each reported sign and symptom to be ranked. Articles that included specific definitions for CES were divided into 3 categories: those that (1) included generalized statements, (2) stated a pathomechanical basis, and (3) defined the syndrome by its clinical presentation. Throughout this review, the frequencies of specific etiologies and pathologies were noted. Together with details of clinical presentation, this enabled a comprehen- sive review of CES. No single aspect of CES within the literature achieved unanimity or consensus; however, a major- ity view indicated that there would be bladder and sensory disturbance (74% and 66% of all articles, respectively). The most commonly cited pathology resulting in CES was identi- fied as the disk (45% of all articles reviewed). Conclusions: There are marked inconsistencies in the cur- rent evidence base surrounding the etiology and clinical pre- sentation of CES, with 17 definitions identified. Subclassifica- tions of the definition of CES are ambiguous and should be avoided. From reviewing 105 articles, a single definition of CES is proposed. For a diagnosis of CES, one or more of the following must be present: (1) bladder and/or bowel dysfunc- tion, (2) reduced sensation in the saddle area, and (3) sexual dysfunction, with possible neurologic deficit in the lower limb (motor/sensory loss, reflex change). Key Words: Cauda equina; Etiology; Polyradiculopathy; Rehabilitation; Signs and symptoms. © 2009 by the American Congress of Rehabilitation Medicine C AUDA EQUINA SYNDROME is rare and is estimated to account for fewer than 1 in 2000 of patients with severe low back pain. 1 Despite the claim that some orthopedic sur- geons see only a few cases throughout their careers, 2 the presence of CES is nevertheless reported in 1% to 16% of lumbar disk herniations 2 and 2% to 3% of all patients with herniated disks who require surgery. 3 Failure to diagnose CES can result in serious morbidity such as loss of bladder, bowel, and sexual function with potential medicolegal consequences. In 2004, it was reported that 48% of finalized cases of CES reported to the Medical Defense Union in the United Kingdom resulted in payment of damages to the claimant (compared with 34% for all United Kingdom claims) with an average settlement of £336,000 (U.S. $549,427), adjusted for claims inflation from the point of settlement to 2003 prices at 10% per annum. Just under half of these cases (notified by Medical Defense Union members) were reported by a general practitioner and involved incorrect or delayed diagnosis. 4 It is therefore imperative that all clini- cians who assess patients with back pain have a detailed knowledge of the clinical presentation of this syndrome. This article reviews the current evidence for the signs and symptoms most commonly associated with CES and considers its definition, clinical presentation, and etiology. The purpose of this article is to propose a universal definition for CES, detail its presentation, and discuss its importance in clinical practice. METHODS In January 2008, a search was undertaken of the electronic databases listed in table 1 using the key search words stated. The search included articles published in any language. Be- cause the purpose of this work was essentially descriptive, no attempt was made to weight the quality of the articles that were identified. The literature comprised case reports, case series, clinical experience, expert opinion, and literature reviews. To ensure consistency in coding, a subset of 5 randomly selected articles was independently reviewed by each of the 3 authors, and the findings were compared. For the main data collection, each From the Southampton University Hospitals (NHS) Trust, Southampton, Hamp- shire (Fraser, Roberts, Murphy), and the School of Health Sciences, University of Southampton, Highfield, Southampton (Roberts), United Kingdom. Presented in part to the Society for Back Pain Research, November 2, 2006, Middlesbrough, United Kingdom, and the World Confederation for Physical Therapy, June 4, 2007, Vancouver, BC, Canada. No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the authors or on any organi- zation with which the authors are associated. Roberts discloses that her University post is funded by the Arthritis Research Campaign. Correspondence to Stuart Fraser, BSc, Southampton University Hospitals (NHS) Trust, Wessex Neurological Centre, Therapy Services Department, Tremona Road, Southampton, United Kingdom, SO16 6YD, e-mail: Stuart.Fraser@suht.swest. nhs.uk. Reprints are not available from the author. 0003-9993/09/9011-01003$36.00/0 doi:10.1016/j.apmr.2009.03.021 List of Abbreviations CES cauda equina syndrome 1964 Arch Phys Med Rehabil Vol 90, November 2009