Improved diffusion of water in lumbar intervertebral discs after spinal manipulation reduce pain.

Study to determine if there are differences in diffusion of water within the lumbar intervertebral discs (IVDs) between LBP Pts who reported reduction in pain intensity after a single spinal manipulation (SM) visit & those who did not.
Beattie PF, PT, PhD, et al. J Orthop Sports PhysTher 2014;44(1):19-29.

Comments: This 2014 study is the first to document that spinal manipulation can result in improved intradiscal diffusion and that this is associated with reduced pain in symptomatic LBP patients. The authors propose that the pain reduction may be due to enhanced gas and nutrient transport, improved removal of metabolic waste products associated with pain, and the positive effect of improved pressure gradients acting on the disc. Improved intradiscal diffusion has not be studied before because until now there was no way to visualize such changes. However, now the “diffusion-weighted MRI” allows diffusion of water within the IVD to be quantified.

Postintervention increases in the diffusion of water w/i intervertebral discs (IVDs) may be a mechanisms linked to pain reduction by these means: Increased diffusion of water within the lumbar IVD
      1) May enhance gas & nutrient transport,
      2) Aid in removal of metabolic waste products associated with pain,
      3) Have a positive effect on internal &/or external pressure gradients acting on the disc.

Increased diffusion w/i IVDs in Pts who receive SM for LBP may be associated w a reduction in pain & provide information regarding a mechanism by which SM affects symptoms. A new application of lumbar MRI - diffusion-weighted MRI allows diffusion of water w/i the IVD to be quantified & provides an estimate of the rate at which water moves w/i the IVDs. This is represented by the apparent diffusion coefficient (ADC).

Methods: 19 LBP Pts (20-45 yrs) given numerical pain rating scales (NPRS) before & after side-posture SM. Pts underwent T2- & diffusion-weighted lumbar MRI immediately before & after receiving a single SM. Pts who reported a decrease in pain intensity of >2 of 11 (0-10) were classified as “within-session responders,” & the others classified as “not–within-session responders.” The apparent diffusion coefficient (ADC), representing the diffusion of water in the nucleus pulposus, was calculated.
Results: Pts who responded (n = 12) had a post-SM increase in ADC at L1-2 (P = .001), L2-3 (P = .002), & L5-S1 (P = .01) vs those who did not respond (n = 7). There were large effect sizes in ADC between responder groups were observed at L1-2, L2-3, & L5- S1.
Conclusion: Changes in diffusion of water w/i the IVDs at L1-2, L2-3, & L5-S1 appear to be related to differences in within-session pain reports following a single SM.