Herniated nucleus pulposus (slipped disk)

Alternative names:

cervical radiculopathy; herniated intervertebral disk; lumbar radiculopathy; prolapsed intervertebral disk; radiculopathy; ruptured disk; slipped disk

Definition:

A condition in which part or all of the soft, gelatinous central portion of an intervertebral disk (the nucleus pulposus) is forced through a weakened part of the disk, resulting in back pain and nerve root irritation.

Causes, incidence, and risk factors:

The spinal vertebrae are separated by cartilage disks, filled with a gelatinous substance, that provide cushioning to the spinal column. These disks may herniate or rupture from trauma or strain, especially if degenerative changes have occurred in the disk.

Radiculopathy refers to any disease condition of the spinal nerve roots. The term "lumbar radiculopathy" means that the lower back nerves are involved; "cervical radiculopathy" means that the neck nerves are involved. Herniated disk is one cause (but not the only cause) of radiculopathy.

Most herniation takes place in the lumbar area of the spine. Lumbar disk herniation occurs 15 times more often than cervical (neck) disk herniation, and it is one of the most common causes of lower back pain. The cervical disks are affected 8% of the time and the upper-to-mid-back (thoracic) disks only 1 to 2% of the time.

Nerve roots (large nerves that branch out from the spinal cord) may become compressed resulting in neurological symptoms such as sensory or motor changes.

Disk herniation occur more frequently in middle aged and older men, especially those involved in strenuous physical activity. Other risk factors include any congenital conditions that affect the size of the lumbar spinal canal.