Strong emotion of any kind has been shown to be linked with strong memories of that moment. The exact physiologic mechanism by which this happens isn’t clear. Neuropeptides or biologic messengers that travel around the body may have something to do with it.
The same effect is associated with stressful medical tests. Studies show that the level of pain reported and remembered for stressful or negative medical tests is higher than when the test was originally done. This phenomenon is called post-exposure modulation.
It means that memory pain of acutely painful experiences is remembered inaccurately because it is exaggerated over time. This is especially true when the delay between experience and recall is six months or more.
Discography is a painful test. It is designed to confirm which disc is damaged. An injection of contrast dye puts pressure on the disc reproducing painful symptoms. It makes sense that a painful discography test done on a patient who is fearful or anxious would result in a heightened memory of the pain.