Lactic Acid and Proteoglycans as Metabolic Markers for Discogenic Back Pain

In Brief Study Design. Disc tissue was removed at surgery from 9 patients with discogenic pain and 9 deformity patients with scoliosis undergoing anterior and posterior spinal fusion. These samples were then analyzed using ex vivo proton high resolution magic angle spinning (HR-MAS) NMR spectroscopy to produce metabolic profiles for comparison between the 2 patient groups. Objective. The goal of this study was to use quantitative ex vivo HR-MAS NMR spectroscopy to identify biochemical markers associated with discogenic back pain. Summary of Background Data. Biomarkers of disc degeneration have been previously described using NMR spectroscopy, but the link between discogenic back pain and biomarkers has not been completely understood. Methods. HR-MAS NMR spectroscopy was performed on snap frozen samples taken from 9 patients who underwent discectomies for painful disc degeneration. The resulting proton NMR spectrums were compared with those from discs harvested from a reference population consisting of 9 scoliosis patients. Results. Spectral analyses demonstrated significantly lower proteoglycan (PG)/collagen (0.31 ± 0.22 vs. 0.77 ± 0.48) and PG/lactate (0.46 ± 0.24 vs. 2.24 ± 1.11) ratios, and a higher lactate/collagen (0.77 ± 0.49 vs. 0.40 ± 0.21) ratio in specimens obtained from discogenic pain patients when compared with scoliosis patients. Conclusion. Our results suggest that spectroscopic markers of proteoglycan, collagen, and lactate may serve as metabolic markers of discogenic back pain. These results provide a further basis of the potential to develop in vivo MR spectroscopy for the investigation of discogenic back pain. High-resolution magic angle spinning (HR-MAS) NMR spectroscopy can be used to quantify compounds associated with discogenic back pain. This supports the feasibility of using magnetic resonance spectroscopic imaging (MRSI) in vivo to noninvasively assess discogenic back pain.