Incomplete cauda equina syndrome presenting with acute urinary retention in the emergency department

Cauda equina syndrome (CES) is a rare but serious neurosurgical emergency that can have devastating longlasting neurologic consequences. CES caused by herniated lumbar discs is rare in the literature. We report an unusual case of incomplete CES due to lumbar disc herniation. The patient presented to our emergency department with acute onset of low back pain, saddle (perineal) anaesthesia, urinary retention and constipation without motor deficit or sciatica. Magnetic resonance imaging (MRI) revealed a large herniated disc originated from the L5-S1 disc space with compression of the cauda equina. This case illustrates that patients with CES accompanying a disc herniation may not have all the characteristic features of CES such as pain radiating to the legs or muscle weakness. We recommend that urgent MRI assessment should be performed in all patients who present with sudden onset of urinary symptoms in the context of lumbar back pain or loss of perineal sensation. (Hong Kong j.emerg.med. 2010;17:498-501)