This abbreviated extract article from National Center for Biotechnology Information of a clinical study done in China is simple and fascinating.
The goal of the study was to determine the natural path of proven discogenic pain, which in these patients was determined by discograms. This process is no longer routinely done in the US because of the risk of worsening the degenerative changes in the disc.
Unfortunately, the natural history of patients with this condition is not particularly good. 80% of the study group are either unchanged or worse over 4 years.