The intervertebral discs are found in the spinal column between successive vertebrae, and consist of an outer fibrous collagen ring (annulus) surrounding an inner mass, the nucleus pulposus(Foster). The discs act as shock absorbers, which cushion the spinal column from forces applied to the musculoskeletal system. The water retention ability of the nucleus declines with age, leading to excessive pressure within the disc, and a stiffening of the disc, causing the fibrous ring to herniate (bulge).
Epidemiological studies have shown that smoking, is a risk factor for intervertebral disc herniation because it causes a significant decrease in oxygen in the avascular disc by vasoconstriction (Foster). Heavy coughing can also cause disc herniation. Sitting unsupported increases the pressure on intervertebral discs, and may contribute to disc herniation. Driving is a risk factor for disc herniation because of the continuous vibration to the spine, and truck drivers are particularly prone to the problem. A weakened annulus is a prerequisite for disc herniation, and an annular tear or weak spot can result from repetitive normal stress from customary activities and physically stressful activities. Although bone has no pain receptors, the discs have associated neurovascular elements, which include pain fibers (Foster). Lower back pain is a common symptom of disc herniation along with stiffness and diminished stability of the spine, unilateral leg pain, numbness, paresthesias, and/or weakness (Ahn, Ahnn, Harlan, Reed and Amundson 230; Foster;). The symptoms are typically in the myotomal and dermatomal distribution of the affected nerve (Ahn, Ahnn, Harlan, Reed and Amundson 230). Patients have deterioration of the disc and dysfunction at the segmental level. They have low back pain which is sometimes associated with leg pain, but no sciatica or radiculopathy. Sciatica can resolve spontaneously from shrinkage of a herni...