Fig 1: Degenerative Disc Disease
(larger view [4])
Fig 2: X-ray of Degenerative Disc Disease
(larger view [5])
Lumbar Degenerative Disc Disease
Degenerative disc disease refers to a syndrome in which a compromised disc causes low back pain [6]. Lumbar degenerative disc disease usually starts with a torsional (twisting) injury to the lower back, such as when a person rotates to put something on a shelf or swing a golf club. However, the pain is also frequently caused by simple wear and tear on the spine.
Despite its rather dramatic label, degenerative disc disease is fairly common, and it is estimated that at least 30% of people aged 30-50 years old will have some degree of disc space degeneration, although not all will have pain or ever receive a formal diagnosis. In fact, after a patient reaches 60, some level of disc degeneration is deemed to be a normal finding, not the exception.
Lumbar degenerative disc disease pain and symptoms
Most patients with lumbar degenerative disc disease will experience low-grade continuous but tolerable pain that will occasionally flare (intensify) for a few days or more. Pain symptoms can vary, but generally are:
- Centered on the lower back, although it can radiate to the hips and legs
- Frequently worse when sitting, when the discs experience a heavier load than when patients are standing, walking or even laying down
- Exacerbated by certain movements, particularly bending, twisting or lifting
The low back pain associated with lumbar degenerative disc disease is usually generated from one or both of two sources:
- Inflammation, as the proteins in the disc space irritate the surrounding nerves, and/or
- Abnormal micro-motion instability, when the outer rings of the disc - the annulus fibrous – are worn down and cannot absorb stress on the spine effectively, resulting in movement along the vertebral segment
Excessive micro-motion, combined with the inflammatory proteins, can produce ongoing low back pain (See Figure 1 [7]).
Fortunately, over time the pain from lumbar degenerative disc disease usually decreases, rather than becoming progressively worse. This is because a fully degenerated disc no longer has any inflammatory proteins (that can cause pain) and usually collapses into a stable position (see Figure 2 [8]), eliminating the micro-motion that generates the pain.
Lumbar degenerative disc disease diagnosis
Following a review of the patient’s history and a physical examination, a formal diagnosis of lumbar degenerative disc disease can be confirmed with magnetic resonance imaging (MRI). MRI findings that are closely linked to a painful disc include disc space collapse of greater than 50% and cartilaginous endplate erosion.
More controversial are MRI findings of early disc space degeneration such as disc desiccation (disc are blacker on a scan because they do not have as much water as a healthy disc), a disc bulge, or an annular tear (tear into the outer annulus of the disc space on a scan that shows up as a bright white spot).
These subtle findings are for the most part just as likely to show up on a scan of someone who has not had pain as one who has had chronic low back pain. Also, these subtler findings are more consistent with natural aging of the back than of a pathological pain producing disc space. Disc degeneration is actually quite common among people who have no pain or other symptoms, so the patient’s history and physical examination are an essential part of the diagnosis.