Central sensitization and altered central pain processing in chronic low back pain: fact or myth?

The authors undertook this review with the objective of analyzing the available literature concerning central sensitization and altered central pain processing in patients with chronic low back pain (LBP). They screened the literature using several electronic search databases. Additional literature was obtained by reference tracking and expert consultation. Studies evaluating central pain processing in conservatively treated patients with chronic LBP were included. Results of studies examining the responsiveness to various stimuli in patients with chronic LBP do not agree. Some studies in patients with chronic LBP have shown exaggerated pain responses after sensory stimulation of locations outside the painful region, while other studies find no differences between patients and healthy people. Studies examining the integrity of the endogenous pain inhibitory systems report unaltered activity of this descending inhibitory system. In contrast, studies analyzing brain structure and function in relation to (experimentally induced) pain provide preliminary evidence for altered central nociceptive processing in patients with chronic LBP. Finally, also psychosocial characteristics, such as inappropriate beliefs about pain, pain catastrophizing, and/or depression may contribute to the mechanisms of central sensitization.

The authors felt an inclination to speculate that ongoing nociception is associated with cortical and subcortical reorganization and could play an important part in the process of the chronification of LBP. They added that future prospective research should explore to what degree these changes are reversible and if this reversibility is associated with improved functioning of patients.