A critical evaluation of discography in patients with lumbar intervertebral disc disease

STUDY DESIGN: The study is a prospective observational study of 48 continuous patients with symptomatic lumbar degenerative disk disease. Each patient underwent discography, MRI, and a biochemical analysis of disk lavage fluid. OBJECTIVES: The purpose of this study was to correlate concordant pain on discography with MRI grade and biochemical markers of inflammation in a clinical setting. SUMMARY OF BACKGROUND DATA: The pathophysiology of degenerative disk disease is complex. Discography is used to differentiate symptomatic from asymptomatic levels. MRI is used to image changes in disk water content. Biochemical assays have identified molecular markers of inflammation. To date, no study has correlated concordant pain on discography with MRI findings and biochemical markers. METHODS: Forty-eight (48) continuous patients with symptomatic lumbar degenerative disk disease gave informed consent for study entry. Patient sex, age, insurance, work status and visual analog score (VAS) were recorded. MRI was obtained and Pfirrmann grading was performed by a single spine surgeon. Discography with disc lavage was performed by a single anesthesiologist. Lavage samples were tested for inflammatory markers with high resolution multi-plex bead immunoassays and ELISA with >5 pg/ml resolution. RESULTS: None of demographic variables was significantly related to concordant pain on discogram by chi-squared tests and Mann-Whitney U-test. The Pfirrmann score was significantly different for patients with and without concordant pain at L3-L4 (p<0.001), but was insignificant at other levels after multitest correction. Pfirrmann scores were significantly different at any level in patients with and without concordant pain. VAS scores were not significantly correlated with opening pressures at any level. Despite the presence of serum proteins in the disk lavage fluid, none of the tested inflammatory mediators was identified by multi-plex bead immunoassays and ELISA. CONCLUSIONS: There are only weak correlations between demographic, discogram, and radiographic variables. Response to discogram cannot be predicted by non-invasive means. The disk lavage method was unable to identify the presence of specific inflammatory peptides with multi-plex immunoassays and ELISA.