Cauda equina syndrome – What is the correlation between clinical assessment and MRI scanning?

UNLABELLED: The indications for magnetic resonance imaging (MRI) in suspected cauda equina syndrome, and the urgency for this investigation are regularly disputed. In this study we assess the ability of neurosurgical residents to predict on clinical grounds in which patients with cauda equina syndrome (CES) this was due to prolapsed intervertebral disc thereby justifying a request for urgent MR imaging. DESIGN: Prospective cohort study of all adult patients with a suspected diagnosis of cauda equina syndrome. SETTING: A single tertiary referral neurosurgical centre. PARTICIPANTS: All patients referred over a four month period with a suspected diagnosis of cauda equina syndrome. RESULTS: MRI was normal in 10 (43%) patients. A disc prolapse causing cauda equina distortion was present in 5 (22%) patients. The diagnostic accuracy of urinary retention, urinary frequency, urinary incontinence, altered urinary sensation and altered perineal sensation were 0.57, 0.65, 0.61 ,0.65 and 0.60 respectively. CONCLUSIONS: Because it is impossible in a significant proportion of patients to exclude the diagnosis of prolapsed intervertebral disc in the context of referral with suspected cauda equina compromise the authors recommend urgent MRI assessment in all patients who present with new onset urinary symptoms in the context of lumbar back pain or sciatica.