Disk herniation is a rupture of fibrous material surrounding the disks that separate the vertebrae of the spine. Each disk is made up of a jelly-like center surrounded by a tough ring of fibres arranged in concentric layers like those of an onion. Any forceful vertical pressure on the disks can cause them to push their fluid contents outward, placing pressure on a spinal nerve that can cause both nerve damage and considerable pain. Herniation may occur suddenly from lifting, twisting, or direct injury, or gradually from degenerative changes. The condition most frequently occurs in the low back region and is also called herniated nucleus pulposus, prolapsed disk, ruptured intervertebral disk, or slipped disk. Disk herniation can also occur in the neck, and less commonly, in the chest area.

Depending on the location, the ruptured material may press directly on nerve roots or on the spinal...