An animal study, published in The Spine Journal, indicates that three medications—iopamidol, lidocaine, and cortisone—used in discography are all associated with significant decreases in cell counts and cell proliferation. This indicates that intradisc medication for discography might contribute to disc degeneration.
Study authors Claudia Eder, Orthopädisches Spital Speising, Wien, Austria, and others reported that Eugene Carragee was the first to show that provocative discography, which is used to distinguish a painful disc from other potential sources of pain, can contribute to disc degeneration. They explained that he showed that “Small needle puncture together with limited pressure injection might accelerate intervertebral disc degeneration.” They added that looking at the medications used in discography (contrast medium for the detection of fissures; anaesthetic for analgesia discography to confirm the findings of provocative discography, and the intradisc injection of cortisone as an additional diagnostic tool) may show that the puncture needle may not be the only cause of degeneration associated with discography. Eder et al reported that the: “Aim of the present study is to investigate the effect of an anaesthetic, a steroid, and a non-ionic contrast agent on healthy interverbral disc cells in vitro.”
The authors placed 12 bovine coccygeal discs into four groups, with the cells in each group being incubated in a different cell culture medium: standard, 3mL iopamidol, 1mL lidocaine, and 10mg cortisone. They analysed the cell count, viability, proliferation, and differentiation features of each group. According to Eder et al, after 24 hours, a small decrease was observed in cell viability in three drug culture groups compared with the standard culture group. However, they noted: “Cell counts were 2.5×104 in the control group, but only 1×104 after incubation in the culture medium containing lidocaine or cortisone. After incubation in culture medium supplemented with iopamidol, cell counts decreased to 0.63×104 cells (p<0.01). Suppression of proliferation continued over time.”
Also, population doubling time significantly increased with drug cultures compared with the control group (16 hours)—25 hours with iopamidol, 21 hours with cortisone, and 38 hours with lidocaine (p<0.01). Imaging did not show any differences between the cells cultured in the standard medium and in iopamidol or cortisone, but Eder et al commented: “Cells cultured in lidocaine, in contrast, showed delayed attachment in the beginning and exhibited a rather round phenotype with short pseudopodia and numerous vacuoles with their cytoplasm.”
Concluding their study, the authors said that more research was needed but added: “Combined with the mechanical trauma caused by the puncturing needle, intadiscal medication might therefore contribute to intervertebral disc degeneration.”