In most cases, spinal infection is caused when an illness or infection somewhere in the body is carried to a disc in the spinal column. Even when the illness has passed, the infection stays in the disc and spreads to the vertebral bones, causing pain and deformity. Bacteria from an infection travels through the bloodstream and into a vertebral disc. Once infected, the soft nucleus center and the fibrous annula wall weaken, decay and collapse. This causes the disc space to close, squeezing down on the nerve root and causing pain.
In a decaying domino effect, the infection spreads to the vertebral bodies above and below the disc. The bones, weakened by the infection, crumble under the weight of the human body. The deformed spinal column pushes into the spinal cord, causing many functions of the body to become impaired. Over time, the deformed vertebrae heal and fuse. This further presses on the nerve roots, causing continuous pain.