The cauda equina (meaning ‘horse’s tail’) is a tail-like array of roots of spinal nerves at the inferior end of the spinal cord. Cauda equina syndrome is the term used to describe paralysis of this part of your nervous system.  Patients usually have a phase of excruciating pain followed by numbness, paralysis and an inability to pass urine which classically is painless – i.e you know you have an overfull bladder but it does not hurt – ‘painless retention’.  An early warning may be numbness around the private parts - where your pants go.  If you notice anything like this, you need to see a doctor.  This syndrome is a surgical emergency and if you have these symptoms you must go to A&E immediately.