  Pain perception, trunk mobility in flexion, extension, and lateral flexion,
and apparent diffusion coefficient (ADC) within nucleus pulposus of all lumbar
discs were collected before and after posterior-to-anterior mobilization in 16
adults with acute low back pain. ADC was computed from diffusion maps and 3
specific portions of the nucleus pulposus were investigated: anterior (ADCant
), middle (ADCmid), and posterior (ADCpost ), and their mean as ADCall , a
summary measure of ADC within nucleus pulposus. Pain ratings were significantly
reduced after mobilization, and mobility of the trunk was significantly
increased. Concomitantly, a significant increase in ADCall values was observed.
The greatest ADCall changes were observed at the L3-L4 and L4-L5 levels and
were mainly explained by changes in ADCant and ADCpost . The simultaneous
reduction in pain and increase of water diffusion within nucleus pulposus has
has been previously observed in subjects with chronic conditions and exists in
the acute phase of the disease. Since the largest changes in ADC were observed
at the periphery of the nucleus pulposus, and taken together with pain
decrease, our results suggest that increased peripheral random motion of water
molecules is implicated in the modulation of the intervertebral disc
nociceptive response.
