'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.