From the Book
Chapter 10
Lumbar Disc Herniation
Clinical Presentation
Figure 10.1
Anormal lumbar disc (above) and a herniated lumbar disc (below). Note the compression of the nerve root as it exits the spinal canal.
Figure 10.2
Side-view illustration of a small lumbar disc herniation and a large lumbar disc herniation. Note that the small herniation causes minimal pressure on the spinal canal.
As discussed in Chapter 2, the lumbar disc is comprised of an inner gel and an outer annulus. The lumbar discs provide stability and resiliency to the lumbar spine. Lumbar disc herniation develops because of a tear in the annulus of the lumbar spine; the inner nucleus pulposus extends beyond the tear, compromising a part of the spinal canal (Figure 10.1). In many cases, lumbar disc herniation develops insidiously as a result of repeated, small micro tears that develop in conjunction with a degenerative disc. In these cases, patients with lumbar disc herniation may be completely without symptoms. Indeed, modern imaging studies have revealed that lumbar disc herniations may be present in a sizable number of individuals who have no symptoms.
Many patients with an acute lumbar disc herniations have symptoms of pain or numbness in conjunction with a pinched or compressed nerve. Acute lumber disc herniation develops because of a sudden and large tear in the annulus, with subsequent rupture of nucleus pulposus material through the tear. Most of these herniations occur posteriorly, that is, toward the back. They also are generally to one side, but occasionally are midline.
