Cauda equina syndrome (CES) describes symptoms caused by a disc from the spine pushing on the nerves at the end of the spinal cord. These nerves supply the legs, bladder, anus and sexual organs, and can become damaged if compressed for too long. Some of the symptoms include low back pain, bladder or bowel dysfunction, amongst others. Most patients with CES require an emergency operation to take pressure off the nerves. Although lots of people attend Emergency Departments with back pain, very few have CES. Unfortunately, CES can be difficult to diagnose and it is not known whether any particular pattern of symptoms can help us rule out the diagnosis without a Magnetic Resonance Image (MRI) scan. This study will try to determine whether any pattern of symptoms can help us identify which patients are very unlikely to have CES. It will also help determine how patients should be treated when they arrive at an Emergency Department with symptoms that could be caused by CES.