A novel paradigm to evaluate conditioned pain modulation in fibromyalgia
Authors Schoen CJ, Ablin JN, Ichesco E, Bhavsar RJ, Kochlefl L, Harris RE, Clauw DJ, Gracely RH, Harte SE
Received 17 June 2016
Accepted for publication 18 July 2016
Published 26 September 2016 Volume 2016:9 Pages 711—719
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Dr Amy Norman
Peer reviewer comments 3
Editor who approved publication: Dr Michael E Schatman
Cynthia J Schoen,1,* Jacob N Ablin,2,* Eric Ichesco,1 Rupal J Bhavsar,3 Laura Kochlefl,1 Richard E Harris,1 Daniel J Clauw,1 Richard H Gracely,4 Steven E Harte1
1Department of Anesthesiology, Chronic Pain and Fatigue Research Center, University of Michigan, Ann Arbor, MI, USA; 2Institute of Rheumatology, Tel Aviv Suorasky Medical Center, and Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; 3Department of Neurology, University of Pennsylvania, Philadelphia, PA, 4Department of Endodontics, University of North Carolina – Chapel Hill, Chapel Hill, NC, USA
*These authors contributed equally to this work
Introduction: Application of noxious stimulation to one body area reduces pain sensitivity in a remote body area through activation of an endogenous pain-inhibitory network, a behavioral phenomenon referred to as conditioned pain modulation (CPM). The efficiency of CPM is predictive of a variety of health outcomes, while impaired CPM has been associated with various chronic pain conditions. Current methods used to assess CPM vary widely, and interest in CPM method development remains strong. Here, we evaluated a novel method for assessing CPM in healthy controls and fibromyalgia (FM) patients using thumb pressure as both a test and conditioning stimulus.
Methods: Sixteen female FM patients and 14 matched healthy controls underwent CPM testing with thumbnail pressure as the test stimulus, and either cold water or noxious pressure as the conditioning stimulus. CPM magnitude was evaluated as the difference in pain rating of the test stimulus applied before and during the conditioning stimulus.
Results: In healthy controls, application of either pressure or cold water conditioning stimulation induced CPM as evidenced by a significant reduction in test stimulus pain rating during conditioning (P=0.007 and P=0.021, respectively). In contrast, in FM patients, neither conditioning stimulus induced a significant CPM effect P-values >0.274). There was a significant difference in CPM magnitude for FM patients compared to healthy controls with noxious pressure conditioning stimulation (P=0.023); however, no significant difference in CPM was found between groups using cold water as a conditioning stimulus (P=0.269).
Conclusion: The current study demonstrates that thumbnail pressure can be used as both a test and conditioning stimulus in the assessment of CPM. This study further confirms previous findings of attenuated CPM in FM patients compared with healthy controls.
Keywords: pressure pain, cold pressor test, diffuse noxious inhibitory controls, quantitative sensory testing
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