Lumbar Disc Disease
Lumbar disc disease often refers to the degeneration of one of the two major portions of a lumbar intervertebral disc: either the annulus fibrosis or the nucleus pulposus. Some diagnosticians and clinical therapists refer to lumbar disc disease the wearing out of one of these portions of the intervertebral disc, while other doctors describe the condition as the diminishing volume of material in the nucleus of the disc. In this article, we will discuss all of the possible cause of disc disease that could affect the inner and outer portions of these lumbar shock absorbers for the lower portion of the spine.
Think of an intervertebral disc as a tire, but one whose interior was filled with a spongy gel interior rather than air. When we sit erect and stand, weight is added to the spine, which slightly compresses downward due to the slight malleability of the discs. This cushioning effect makes movement such as walking and jumping less jarring to the spine. The disc separate the vertebral bones so that they don't rub together, causing pathology such as osteoarthritis and bone spurs.
Loss of Disc Volume: The intervertebral discs change in height and composition over the course of the night and day. As we put weight on our spines throughout the day, gravity presses down on them, causing water and other nutrients to be pressed out of them. When we lie down at night, these discs re-absorb water and nutrients and they discs expand again. This is the reason why we are slightly taller in the morning than at night.
As we get older, these discs lose their overall volume of water and other materials within its gel-matrix. As these discs lose the amount of fluid contained within its nucleus pulposus, they become less flexible and they lose their shock absorbing capabilities. These discs become flatter and may eventually shrink to the point that they fail the separate the vertebra from contacting one another.
Lumbar Disc Herniation: A lumbar disc herniation affects the tough outer portion of the disc, known as the annulus fibrosus. The annulus fibrosis is made up several layers of tough collagen fibers that help the disc maintain its essential round shape. If one or more sections of the disc become weak, it may bulge outwards at its weakest point and possible impact the structures around it. The amount of disability that a person experiences related to this bulging outwards of the disc's envelope depends on whether the spinal cord itself or the spinal nerves are compressed.
If the annulus becomes torn completely, then the spongy gel material in its center may spill through this fissure. A disc herniation may occur due to an episode of trauma or injury. It is more likely however, that the damage to the disc's wall occurred gradually over a period of months or years. The four stages to a lumbar herniated disc are:
- Disc degeneration: Like the treads of a tire, the number of layers composing the annulus may decrease and the strength of these collagen fibers may diminish. This may cause the disc to begin to weaken.
- Prolapse: The outer wall of the disc may less tough, and it may bulge outward at its weakest point. This prolapsed of the disc is also known as a protruding disc or a bulging disc. The spinal nerves and spinal canal may or may not be affected by this outward protuberance.
- Extrusion: At this point, the wall goes beyond just becoming weak, and a complete break occurs. The material in the nucleus flows through this break in the wall but does not extend outside of the disc.
- Sequestered Disc or Sequestration: At this point the nucleus material breaks all the way through the edge of the disc and goes outside of it.