Reliability of clinical assessment in diagnosing cauda equina syndrome

Cauda equina syndrome (CES) is a neurological syndrome presenting with non-specific symptoms and signs that often leads to diagnostic confusion and delay. Acute onset CES is a surgical emergency. The common aetiology is a prolapsed lumbar disc. If the diagnosis is missed, it can have devastating consequences for the patient and a high financial cost to healthcare providers. The objective of this study was to evaluate the efficacy of clinical assessment in clinching the diagnosis. Eighty patients who underwent urgent clinical assessment and magnetic resonance imaging (MRI) for suspected CES over a 1-year period (from January 1st 2008 to 31 December 2008) were included in the study. Fifteen of these patients had a CES and underwent urgent lumbar discectomy and decompression. Medical notes and MRI scans of all these patients were reviewed. The presenting symptoms and signs were analysed against a positive MRI scan. Chi-square test with Yates correction was used to test association of each clinical symptom and sign for a positive MRI. In this study, only 18.8% of assessed patients had a CES producing compression seen on the MRI. Presence of saddle sensory deficit was the only clinical feature with a statistically significant association with MRI positive CES (p=0.03). This series shows that saddle sensory deficit has a higher predictive value than other clinical features in diagnosing a CES. However, as there is no symptom or sign which has an absolute predictive value in establishing the diagnosis of CES, any patient in whom a reasonable suspicion of CES arises must undergo urgent MRI to exclude this diagnosis.