Advances in the diagnosis of degenerated lumbar discs and their possible clinical application.

PURPOSE: One possible source of chronic low back pain is a degenerated intervertebral disc. In this review, various diagnostic methods for the assessment of the presence of degenerative changes are described. These include clinical MRI, a number of novel MRI techniques and nuclear magnetic resonance spectroscopy. METHODS: Non-systematic literature review. RESULTS: Clinical MRI is the most commonly employed technique to determine the general "health status" of the intervertebral disc. Novel MRI techniques, such as quantitative MRI, T1ρ MRI, sodium MRI and nuclear magnetic resonance spectroscopy, are more sensitive in quantifying the biochemical changes of disc degeneration, as measured by alteration in collagen structure, as well as water and proteoglycan loss. As potential future diagnostic alternatives, miniature sensors are currently being developed to measure parameters associated with the disc degeneration cascade, such as intradiscal pressure and PG concentration. However, none of the methods listed above show sufficient specificity to identify a degenerated disc as the actual source of the pain. Provocative discography is the only test aimed at a direct diagnosis of discogenic pain, but it has a high false positive rate and there is some evidence of long-term adverse effects. Imaging techniques have also been tested for this purpose, but their validity has not been confirmed and they do appear to be problematic. CONCLUSIONS: A reliable diagnostic tool that could help a clinician to determine if a disc is the source of the pain in patients with chronic LBP is still not available. New MRI techniques are under investigation that could result in a significant improvement over current methods, particularly as they can allow monitoring, not only of morphological but also of biochemical changes.