The clinical features and outcome of scan-negative and scan-positive cases in suspected cauda equina syndrome: a retrospective study of 276 patients

Abstract

BackgroundThe majority of patients presenting with suspected clinical cauda equina syndrome (CES) have no identifiable structural cause for their symptoms (‘scan-negative’ CES). Understanding these patients aids clinical differentiation and management in CES.MethodsA retrospective electronic note review was undertaken of patients presenting with suspected CES, defined as ≥ 1 of acute bladder, bowel, sexual dysfunction or saddle numbness, to a regional neurosciences centre. We investigated radiology, clinical features, psychiatric and functional disorder comorbidities and outcome of patients with ‘scan-negative’ CES and patients with MRI confirmed compression of the cauda equina (‘scan-positive’ CES).Results276 patients were seen over 16 months. There were three main radiologically defined patient groups: (1) ‘scan-positive’ CES (n = 78, mean age 48 years, 56% female), (2) ‘scan-negative’ CES without central canal stenosis but with lumbosacral nerve root compression not explaining the clinical presentation (n = 87, mean age 43 years, 68% female) and (3) ‘scan-negative’ CES without neural compromise (n = 104, mean age 42 years, 70% female). In the two ‘scan-negative’ groups (no neural compromise and nerve root compression), there were higher rates of functional disorders (37% and 29% vs. 9%), functional neurological disorders (12% and 11% vs 0%) and psychiatric comorbidity (53% and 40% vs 20%). On follow-up (mean 13–16 months), only 1 of the 191 patients with ‘scan-negative’ CES was diagnosed with an explanatory neurological disorder (transverse myelitis).ConclusionsThe data support a model in which scan-negative cauda equina syndrome arises as an end pathway of acute pain, sometimes with partly structural findings and vulnerability to functional disorders.Electronic supplementary materialThe online version of this article (10.1007/s00415-018-9078-2) contains supplementary material, which is available to authorized users.

What is the incidence of cauda equina syndrome? A systematic review

“…Although final diagnoses in patients without cauda equina compression include demyelination, myelitis, and infection, a structural cause is not found in the majority of patients. 26 Further characterization of these patients to identify potentially distinguishing features such as Hoover's sign of functional weakness 26 could increase the yield of MRI for suspected CES. However, due to the significance of a missed diagnosis, expansion of local out-of-hours MRI provision is more likely to improve care for those investigated for CES with and without structural radiological cauda equina compression.…”

“…Only 2 studies described findings on MRI defining a diagnosis of CES based on the finding of canal compromise, which was more than 50% in one study 29 and more than 75% in the other. 26 Three studies stated that cauda equina compression was determined by the reporting radiologist but did not state the criteria used. 15,20,32 The cause of cauda equina compression was described in 6 studies.…”

Cauda equina syndrome

“…CES is diagnosed when there are both clinical features of CES and evidence of compression of the cauda equina on magnetic resonance imaging (MRI). This poses a challenge since: ( a ) some of the features of CES occur frequently in patients without radiological evidence of CES,34 and ( b ) radiological evidence of central disc prolapse causing compression of the cauda equina occurs in patients without clinical features of CES 5…”

“…Around half of patients with CES have bilateral sciatica 4711. Sciatica is pain or altered sensation in a nerve root distribution that generally goes below the knee to the foot.…”

“…Three useful UK studies retrospectively examined the clinical features of sequential patients referred to tertiary units with features of suspected CES who underwent MRI scans 347. Of the total of 413 patients in the three studies, 106 (26%) had CES.…”