What exactly is cauda equina syndrome?

Severe nerve pinch: There is a bundle of nerves in the lumbar spine that hang down from the spinal cord. This is the cauda equina or the horse's tail. The syndrome is caused by severe compression or injury of the entire bundle. It results in bilateral leg weakness, bowel and bladder incontinence. It's commonly caused by a large herniated disc, but also by tumor, trauma or hemorrhage.