Effect of Pain Induction or Pain Reduction on Conditioned Pain Modulation in Adults: A Systematic Review.
OBJECTIVE
Pain facilitation as well as pain inhibition might be present in chronic pain patients. A decreased efficacy of pain inhibition can be measured by conditioned pain modulation (CPM). The use of the CPM paradigm in scientific research has boosted over the last few years and is recognized for its high clinical relevance in chronic pain patients. It is, however, unclear whether the presence of pain and possible modulations of pain influences the efficacy of endogenous pain inhibition, measured by CPM. This systematic literature study aimed to provide an overview of the effects of clinical pain and experimental pain induction or pain reduction on CPM in adults.


METHODS
A systematic literature search was conducted in the databases "Pubmed" and "Web of Science". Only full texts of original studies regarding the effect of clinical pain and experimentally induced pain and pain reduction on CPM in adults were included. The included articles were scored on methodological quality and through a CPM paradigm.


RESULTS
Twelve articles of good to moderate quality were included in this review. Some pain inhibitory medication and oral contraceptives inhibit the CPM mechanism. Removing chronic pain by surgery results in an improved CPM response. This effect is not observed when removing acute pain.


CONCLUSIONS
Analgesic medication and oral contraceptives might inhibit the CPM response, whereas there is limited evidence that pain-relieving surgery improves CPM in chronic pain patients. However, the results merely suggest that decreased CPM values (as in chronic pain patients) can improve after elimination of pain.
Department of Rehabilitation Sciences and Physiotherapy, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.|Pain in Motion Research Group.
Dorien
D
Goubert
Department of Rehabilitation Sciences and Physiotherapy, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.
Lieven
L
Danneels
Department of Rehabilitation Sciences and Physiotherapy, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.
Barbara
B
Cagnie
Department of Rehabilitation Sciences and Physiotherapy, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.|Pain in Motion Research Group.
Jessica
J
Van Oosterwijck
Department of Rehabilitation Sciences and Physiotherapy, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.
Kim
K
Kolba
Department of Rehabilitation Sciences and Physiotherapy, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.
Heleen
H
Noyez
Department of Rehabilitation Sciences and Physiotherapy, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.|Pain in Motion Research Group.|Department of Rehabilitation Sciences and Physiotherapy, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium.
Mira
M
Meeus
D000328:Adult; D059350:Chronic Pain / Q000523:psychology* / Q000628:therapy*; D003213:Conditioning, Psychological; D006801:Humans; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement / Q000379:methods; D017288:Pain Threshold / Q000502:physiology
acute pain; chronic pain; clinical pain; conditioned pain modulation; conditioning stimulus; diffuse noxious inhibitory control; experimental pain; pain inhibition