Novel Characterization Of Thermal Temporal Summation Response By Analysis Of Continuous Pain Vs Time Curves And Exploratory Modeling
Received 13 June 2019
Accepted for publication 31 October 2019
Published 2 December 2019 Volume 2019:12 Pages 3231—3244
Checked for plagiarism Yes
Review by Single anonymous peer review
Peer reviewer comments 2
Editor who approved publication: Dr E Alfonso Romero-Sandoval
Jiang-Ti Kong,1 Epifanio Bagarinao,2 Richard A Olshen,3 Sean Mackey1
1Department Of Anesthesiology, Perioperative And Pain Medicine, Stanford University School of Medicine, Stanford, CA, USA; 2Brain And Mind Research Center, Nagoya University, Nagoya, Japan; 3Department of Biomedical Data Science, School of Medicine, Stanford University, Stanford, CA, USA
Correspondence: Jiang-Ti Kong
Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School Of Medicine, 1070 Arastradero Road, Suite 200, Palo Alto, CA 94304, USA
Tel +1 650-723-1235
Fax +1 650-725-9642
Background: Temporal summation (TS) refers to the increased perception of pain with repetitive noxious stimuli. While thermal TS is generally considered a behavioral correlate of spinal windup, noxious heat pulses also trigger additional sensory processes which were modeled in this study.
Methods: Nineteen healthy volunteers (9 females, mean age 29.2, SD 10.5) underwent two identical TS experiments, spaced a week apart. The TS paradigm consisted of 10 identical heat pulses with individualized temperatures at the thenar eminence (0.5Hz). We extracted 3 features from continuous TS response curves: Lag, time to first feel pain; Slope, the rate of pain increase between the first and most painful heat pulse; and Delta, the maximum drop in pain after peak pain is reached. We then examined the within-individual stability of these features, followed by the Pearson’s correlations among these features and between the features and negative affect.
Results: All 3 features were stable over 1 week. Lag and Delta were negatively correlated (r = −0.5, p = 0.042). Slope did not correlate with Lag or Delta, but strongly correlated with a traditional TS measure, first pulse pain and peak pain difference (r = 0.91, p < 0.0001). Negative affects such as trait and state anxiety were negatively correlated with baseline (r = −0.49, p = 0.031) and peak stimulating temperature (r = −0.48, p = 0.039), respectively, suggesting an association between anxiety and greater pain sensitivity.
Conclusion: We were able to decouple spinal windup from other perceptual processes generated by phasic thermal TS paradigms and demonstrate temporal stability of these curve features. These curve features may help better characterize the complex sensory response to noxious heat pulses and serve as biomarkers to profile patients with chronic pain.
Keywords: thermal, temporal summation, windup, anxiety, depression, test–retest stability
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