Many studies trying to unravel the chronic pain picture suggest that differences in central pain-transmitting systems may explain chronic pain. Our body disposes of several internal mechanisms to regulate the pain, which are deficient in patients with whiplash associated disorders, fibromyalgia, etc. We reviewed the central pain processing in patients with chronic low back pain (LBP) (Roussel et al. 2013).
Several studies suggest that central pain mechanisms are altered in patients with chronic LBP, but the results are not equivocal. Some studies demonstrated that when a mechanical stimulus is provided patients with LBP experience pain faster than healthy controls, even outside the region of the lower back or lower extremities. It is clear that these lowered pain thresholds at sites not related to the LBP only can be explained by dysfunctional central mechanisms and not by local dysfunctions. However, other studies report no difference between patients with LBP and healthy controls. Similar contradicting results are found when a painful stimulus is repeatedly provided to patients with chronic LBP (temporal summation). Differences in experimental protocols may account for the observed discrepancies, such as stimulation procedure or outcome parameters. Not all studies evaluated whether patients used centrally acting pain medication, which may also influence the study’ results.
More consistent results are found regarding the powerful internal pain inhibiting system which seems to function properly in patients with LBP. On the other hand, growing evidence demonstrates alterations in both brain structure and brain function, including alterations in the biochemical profile of the brain in patients with chronic LBP. Finally, psychosocial characteristics, such as inappropriate beliefs about pain and/or depression may contribute to the altered pain mechanisms.
About Nathalie Roussel
Nathalie is Assistant Professor at the Artesis University College of Antwerp and Visiting Professor at the University of Antwerp (Belgium). She works as post-doctoral researcher at the Vrije Universiteit Brussel and is a member of Pain in Motion. Her work focusses on pain processing mechanisms and on the relationship between pain and movement in patients with chronic musculoskeletal pain and in sportsmen. Special interest goes to the evaluation and treatment of patients with low back pain. She is (co)-author of 27 peer reviewed publications.
Reference
Roussel NA, Nijs J, Meeus M, Mylius V, Fayt C, & Oostendorp R (2013). Central Sensitization and Altered Central Pain Processing in Chronic Low Back Pain: Fact or Myth? ClinJ Pain, 29 (7), 625-638 PMID: 23739534