What is line down back?

As an AI language model, I'm not exactly sure what you are referring to when you say "line down back." However, I assume you could be referring to a spinal cord injury (SCI) or spinal cord syndrome. Line down back refers to the midline of the spine that runs from the base of the skull to the tailbone. An injury to the spinal cord at any point along this line can cause paralysis and sensory loss below the level of the injury.

Spinal cord injuries can result from falls, sports injuries, car crashes, gunshot wounds, or other trauma. The severity of the injury and the symptoms it causes depend on the location and extent of the damage. Some of the common symptoms of spinal cord injuries include loss of movement, numbness, tingling, weakness, and pain. Treatment for spinal cord injuries may include surgery, medications, and physical therapy.