Researchers from Duke University show that back pain is usually caused by a person's immunity attacking the disc in the same way that it attacks invading germs, not by a broken disc pressing on a nerve (Arthritis & Rheumatism, July 2010). They found that people with back pain associated with damaged discs have high levels of Interleukin-17, produced by your immune lymphocytes and known to cause asthma, rheumatoid arthritis and other autoimmune diseases.
The natural history of back pain from "disc disease" usually starts after you hurt your back. You often appear to recover after several weeks or months of pain. However, the back pain can recur any time later, even many years after your original back problem.
The bones of your spine are separated by pads called discs . When you hurt your back, you can crack the outer layers of a disc, so the softer inner layers protrude through the cracks into the spinal canal. The softer inner layers of a disc normally are not exposed to the immune system. So the human immune system does not recognize it as self and attacks it in the same way that it attacks invading bacteria and viruses. The protruding inner portions of the disc then swell to press against nearby nerves to cause pain. This research implies that the immune reaction that attacks the protruding broken inner portion of the disc causes the disc to swell and press on nerves. The authors feel that the pain is not caused primarily by broken pieces of a disc pressing on nerves so it is incorrect to use the common term "slipped disc".
If this is true, future treatment for disc disease would be to inhibit the lymphocytes that make interleukin-17. This would allow the treatment to reduce pain without blocking the body's ability to prevent infections and tumors. Either way, surgery for "disc disease of the back" has among the highest failure rates of any surgery today.