Low back pain affects millions of people and is quite common. Most often, it resolves on its own. In rare occasions, severe back pain can be a symptom of cauda equina syndrome, a serious neurologic condition in which damage to the cauda equina network of nerves causes loss of function of the spinal cord. Cauda equina syndrome can be caused by a variety of medical conditions including herniated disks, tumors, fractures or infections. The most common cause, however, is a prolapsed or herniated disk.