Ninety percent of Americans will suffer from back pain at some point in life. Of those, ten percent will turn into what's called chronic back pain, which is pain that persists for more than three months.
One of the reasons for chronic pain is degenerative disc disease, which refers to pain that is emanating from the intervertebral disk. The intervertebral disks are the shock absorbers between the bony vertebrae in one's spinal column.
The spinal disc does have a nerve supply and therefore can experience pain. The nerve supply comes from the outer part of the disc, called the anulus. If the lumbar disk undergoes degeneration or trauma and there is damage to the anulus, it can be painful. The inner part of the intervertebral disc, the nucleus pulposus, has no nerve endings and does not experience pain. This can be likened to a jelly donut, where the gelatinous part does not hurt at all, and the outer covering of the donut can be painful as it cracks or tears.
What about disc bulges? Over forty percent of individuals over the age of 40 have disc bulging. It is analogous to a car tire that is losing air and starts to bulge from the weight of the car. In the case of the bulging disk in the human spinal column, it is not always painful. In fact, most disk bulges in humans are not painful and are simply seen on imaging studies as an incidental finding.
Once the anulus has tears or cracks from trauma or degeneration, pain can result. This pain may be completely in the back and may also radiate into the buttocks or flank area. If infection results and envelopes one of the spinal nerve roots coming out from the spine, one may also experience sciatica from what's called chemical radiculitis.
There is not a gold standard diagnostic test to see if the intervertebral disc is the source of back pain being experienced. A lumbar diagram is an outpatient study that attempts to reproduce the back pain to make the true diagnosis of symptomatic degenerative disc disease. It is a painful test and does not help a patient's symptoms. It only allows for a diagnosis confirmation.