What is the cause for radiating back pain?

Q: I have back pain radiating to right leg till the small finger since 4 years. I have got my X-rays done so many times and even MRI was done which says I have a small annular bulge at L3/L4 with insignificant effect on lumbar nerve and also mild bulges at L4 and L5. Whenever I visit the orthopedic consultant, he prescribes me pain killers or muscle relaxants, which make me feel good and there is no pain when I take medicines. But time to time I have pain in my lower back and even in my legs. From one week onwards I have severe pain in both of my legs. My job is in computers which requires lot of sitting. I am tired of taking medicines. If you could help me in this regard I will be grateful.

A:Sometimes a low resolution scan is unable to identify a small bulge which may be just under the nerve. There are situations where the disc comes out only on standing and this may be missed even on the best scan. One way of evaluating this if the suspicion is high is to do a discogram where a dye is injected into the suspected offending disc. The pressure makes the disc come out and reproduces the pain. Also the integrity of the disc can be evaluated by the dye patterns.