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The intervertebral disc is an important structure that is found between each vertebra in the spinal column. These discs are designed to absorb pressure and keep the spine flexible during movements. Without the cushion effect given by the discs, the vertebrae in the spine would not be able to provide the movement needed to bend and twist.
With injury or age, intervertebral discs can become damaged, causing discogenic low back pain. Analgesic discography represents a useful tool in diagnosis and even treatment of discogenic pain. During this procedure analgesic drugs are injected into the center of the disc and if the pain improves significantly, this indicates that the suspected disc is the source of the pain.
Two of the most commonly local anesthetics used are lidocaine and bupivacaine. Several in vitro studies have reported cytotoxic effects of these drugs on intravertebral disc cells, however, there is currently no consensus on the clinical consequences of this procedure on disc degeneration. Therefore, researchers from Hokkaido University Graduate School of Medicine performed the first ex vivo and in vivo studies in order to investigate the deteriorative effects of a single injection of lidocaine or bupivacaine on intervertebral disc degeneration using a rabbit model.
The results showed that both lidocaine and bupivacaine significantly induced time-dependent cell death in the organ culture model within 7 days from the injection. On the other hand, when assessing long-term (6-12 months) in vivo effects of single local injection of the local anesthetic agents, no significant difference in cell death was found. In fact, no degeneration was induced other than the initial mechanical damage of the pressurized injection. MRI capturing T2-weighted, mid-sagittal images of treated discs were analyzed qualitatively and quantitatively. Image assessment and quantification of alterations in intravertebral disc structure was performed using Analyze software comparing the images with data from untreated control discs.
See also: Intervertebral Disc Degeneration, Programmed Cell Death and a Targeted Therapy That Could Help
Gold standard treatment for symptomatic relief of severe and chronic back pain is currently surgical removal of the diseased disc followed by fusion of the adjacent vertebral bodies. Spinal fusion however places limitations on flexibility and stress on adjacent spine segments. Recently, there has been a growing interest in developing strategies that are also able to repair or regenerate the degenerated disc biologically. Biological therapeutics have the potential to repair damaged tissue altering cell phenotype, regenerating matrix components, augmenting tissue with reparative cells and delivering bioactive materials to reestablish disc biomechanics and serve as a template for cell-based regeneration.
The in vivo experimental data collected in this study indicate that there is no strong evidence to suggest that analgesic discography with local anesthetics has the potential of inducing intervertebral disc degeneration. Further studies are planned in order to fully understand differences in ex vivo and in vivo studies to help develop low back pain treatments that will significantly reduce the loss of quality of life and morbidity and improve outcomes.
Tags: Orthopedic