Water Diffusion and Degenerative Lumbar Intervertebral Disc Disease
Discogenic pain is the most common type of low back pain caused by mechanical damage to a disc. Usually, this pain worsens with axial loading, sitting, lumbar flexion or extension and disappears upon lumbar flexion or lying supine. Additionally, discogenic pain may include stiffness or radiating sensations to buttocks, flanks or lower extremities.
Many mechanical and biological mechanisms have been proposed to explain the pathophysiology of disc degeneration and pain. These include tear of the annulus fibrosis, loss of disc height, altered loading patterns and stability issues for motion segments. These effects are believed to be most influential in producing symptoms associated with degenerative lumbar intervertebral disc disease (LDIDD).
Water diffusion within the nucleus pulposus and its influence on pain perception are well understood, yet how exactly this occurs remains elusive. That is because IVDs consist of collagen fibers which tend to diffuse along a straight line; furthermore, MRI techniques using T2-weighted imaging may not enable investigation of anisotropic diffusion within natural tissue samples.
In this study, we evaluated the apparent diffusion coefficient (ADC) in 16 adults with acute LBP. The ADC was calculated from midsagittal diffusion weighted MR images of all lumbar IVDs and computed for specific portions of the nucleus pulposus: anterior, middle, and posterior.
These 3 areas were then compared to the mean ADCall, a measure of all ADCs within the nucleus pulposus. The change in ADCant and ADCpost correlated with changes in pain rating and trunk mobility; those who experienced greater increases in both measures showed significantly greater pain reduction.
These findings confirm those of previous studies, in which PA lumbar mobilization9 and prone press-ups9 exercises were found to reduce pain and increase ADC within the nucleus of IVD in chronic LBP subjects. However, these new data provides insight into the effect of a relatively brief duration treatment on pain intensity levels and NP water diffusion in an older population with higher pain intensity levels.
