Common Lumbar Disc Dysfunctions
Between each of the vertebrae (bones) in the spine is a disc. These soft, gelatinous shock-absorbing pads keep the vertebrae from rubbing together. Endplates line the ends of each vertebra and help hold individual discs in place. Each disc contains a tire-like outer band (the annulus fibrosus) that encases a gel-like substance (the nucleus pulposus). Nerve roots exit the spinal canal through small passageways between the vertebrae and discs. In a young individual, the disc is soft and elastic. But, over time, the disc gradually looses its elasticity and is more vulnerable to injury.
A herniated disc is localized displacement of disc material beyond the normal margins of the intervertebral disc space. It is sometimes referred to as a herniated nucleus pulposus or HNP. The pain accompanying disc herniation may be caused by direct pressure on the nerve root, breakdown products from a degenerated nucleus pulposus or by an autoimmune reaction. Patients with a herniated disc often experience decreased pain with walking and standing and increased pain with sitting and forward bending.
A bulging disc is any disc in which the contour of the outer anulus extends beyond the edges of the disc space. Bulging discs may or may not be representing pathologic change or normalcy. Bulging discs are not a form of herniation and may not be the cause of pain. And, unlike herniated discs that typically are the result of an injury or trauma to the spine, bulging discs typically occur gradually over time.