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Pain Practice : the Official Journal of... Nov 2015Pain 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... (Review)
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.
CONCLUSION
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.
Topics: Adult; Chronic Pain; Conditioning, Psychological; Humans; Male; Middle Aged; Pain Measurement; Pain Threshold
PubMed: 25387406
DOI: 10.1111/papr.12241 -
Scandinavian Journal of Pain Apr 2019Background and aims Endogenous pain modulation can be studied in humans by conditioned pain modulation (CPM): pain induced by a test stimulus is attenuated by a...
Background and aims Endogenous pain modulation can be studied in humans by conditioned pain modulation (CPM): pain induced by a test stimulus is attenuated by a distantly applied noxious conditioning stimulus. The detection of impaired CPM in individual patients is of potential importance to understand the pathophysiology and predict outcomes. However, it requires the availability of reference values. Methods We determined reference values of CPM in 146 pain-free subjects. Pressure and electrical stimulation were the test stimuli. For electrical stimuli, we recorded both pain threshold and threshold for the nociceptive withdrawal reflex. Cold pressor test was the conditioning stimulus. The 5th, 10th and 25th percentiles for the three tests were computed by quantile regression analyses. Results The average thresholds increased after the conditioning stimulus for all three tests. However, a subset of subjects displayed a decrease in thresholds during the conditioning stimulus. This produced negative values for most of the computed percentiles. Conclusions This study determined percentile reference values of CPM that can be used to better phenotype patients for clinical and research purposes. The negative value of percentiles suggests that a slightly negative CPM effect can be observed in pain-free volunteers. Implications Pain facilitation rather than inhibition during the conditioning stimulus occurs in some pain-free volunteers and may not necessarily represent an abnormal finding.
Topics: Adult; Conditioning, Psychological; Electric Stimulation; Female; Healthy Volunteers; Humans; Male; Pain Measurement; Pain Threshold; Pressure; Reference Values; Switzerland
PubMed: 30699074
DOI: 10.1515/sjpain-2018-0356 -
Pain Practice : the Official Journal of... Mar 2024Controversy exists with the presence of alterations in descending pain inhibition mechanisms in patients with non-specific neck pain (NSNP). The aim of the present study...
BACKGROUND
Controversy exists with the presence of alterations in descending pain inhibition mechanisms in patients with non-specific neck pain (NSNP). The aim of the present study was to evaluate the status of conditioned pain modulation CPM, remote pressure pain thresholds (PPT), and psychological factors in a specific subgroup of patients with NSNP such as young adult students. In addition, possible associations between CPM, psychological factors, and pain characteristics were analyzed.
METHODS
Thirty students with recurrent or chronic NSNP and 30 pain-free students were included in this cross-sectional study. The following measures were assessed: CPM, remote PPT, psychological factors (depression, anxiety, pain catastrophizing, and kinesiophobia), pain characteristics (duration, intensity, severity of chronic pain, interference with daily life), and central sensitization inventory (CSI).
RESULTS
No significant differences were found in the efficacy of CPM between students with chronic or recurrent NSNP and pain-free students (β coefficient = -0.67; 95% CI = -1.54, 0.20). However, students with pain showed a significantly higher remote PPT (mean difference = -1.94; 95% CI = -2.71, -1.18). and a greater presence of anxious (mean difference = 6; 95% CI = 2, 9) and depressive symptoms (mean difference = 8.57; 95% CI = 3.97, 13.16). In addition, significant moderate or strong correlations were found between CPM and pain intensity (partial r = 0.41), pain catastrophizing and mean pain intensity (r = 0.37), grade (r = 0.50), and interference of pain (r = 0.57), kinesiophobia and disability (r = 0.38), and depression and CSI (r = 0.39).
CONCLUSIONS
Young adult students with chronic or recurrent NSNP present remote hyperalgesia and symptoms of depression and anxiety but not dysfunctional CPM.
Topics: Humans; Young Adult; Chronic Pain; Neck Pain; Cross-Sectional Studies; Pain Threshold; Pain Measurement
PubMed: 37905310
DOI: 10.1111/papr.13313 -
Scandinavian Journal of Pain Apr 2022The interaction between pain and cognition includes a concurrent negative effect of pain on cognitive performance and an analgesic effect of cognitive distraction on...
OBJECTIVES
The interaction between pain and cognition includes a concurrent negative effect of pain on cognitive performance and an analgesic effect of cognitive distraction on pain experience. The purpose of this exploratory study was to investigate the role of pain intensity and task complexity on this interaction.
METHODS
Two experiments were conducted in healthy volunteers. In both experiments, participants completed 3 conditions: a pain only condition (consisting of the cold pressor test), a cognition only condition (consisting of the cognitive task) and a combined condition (concurrent administration of the cold pressor and cognitive task). In experiment I, participants performed one out of three possible tasks that differed in cognitive load (low, medium, high). In experiment II the parameters of the pain stimulus, induced by a cold pressor test, were adapted and only the high load cognitive task was employed. Pain scores, reaction times, and accuracy rates were recorded.
RESULTS
In experiment I, cognitive distraction significantly decreased pain scores, irrespective of the cognitive load of the task. Pain did not affect cognitive performance. In experiment II, pain diminished accuracy rates. No effect of cognitive distraction on pain was observed. Individual characteristics did not noticeably influence the interaction between pain and cognition.
CONCLUSIONS
The results of this study suggest a two-way interaction, however no evidence for a simultaneous bidirectional relationship was found. Cognitive distraction successfully reduces pain, up until a certain point where this relationship is reversed, and pain starts to interfere with cognitive performance. This may imply that priorities shift at a certain pain-threshold, however further research should confirm this hypothesis. This study could contribute to further understanding of cognitive mechanisms related to pain perception.
Topics: Attention; Cognition; Humans; Pain; Pain Measurement; Pain Threshold
PubMed: 34727588
DOI: 10.1515/sjpain-2021-0119 -
Scandinavian Journal of Pain Jul 2023Conditioned pain modulation is a commonly used quantitative sensory test, measuring endogenous pain control. The temporal stability of the test is questioned, and there... (Randomized Controlled Trial)
Randomized Controlled Trial
OBJECTIVES
Conditioned pain modulation is a commonly used quantitative sensory test, measuring endogenous pain control. The temporal stability of the test is questioned, and there is a lack of agreement on the effect of different pain conditions on the conditioned pain modulation response. Thus, an investigation of the temporal stability of a conditioned pain modulation test among patients suffering from persistent or recurrent neck pain is warranted. Further, an investigation into the difference between patients experiencing a clinically important improvement in pain and those not experiencing such an improvement will aid the understanding between changes in pain and the stability of the conditioned pain modulation test.
METHODS
This study is based on a randomized controlled trial investigating the effect of home stretching exercises and spinal manipulative therapy vs. home stretching exercises alone. As no difference was found between the interventions, all participants were studied as a prospective cohort in this study, investigating the temporal stability of a conditioned pain modulation test. The cohort was also divided into responders with a minimally clinically important improvement in pain and those not experiencing such an improvement.
RESULTS
Stable measurements of conditioned pain modulation were observed for all independent variables, with a mean change in individual CPM responses of 0.22 from baseline to one week with a standard deviation of 1.34, and -0.15 from the first to the second week with a standard deviation of 1.23. An Intraclass Correlation Coefficient (ICC3 - single, fixed rater) for CPM across the three time points yielded a coefficient of 0.54 (p<0.001).
CONCLUSIONS
Patients with persistent or recurrent neck pain had stable CPM responses over a 2 week course of treatment irrespective of clinical response.
Topics: Humans; Pain Threshold; Pain Measurement; Neck Pain; Prospective Studies; Pain Management
PubMed: 36869854
DOI: 10.1515/sjpain-2022-0084 -
Scandinavian Journal of Pain Jan 2023Paradoxical sensations, known as thermal pain illusions, can be evoked by painful cold-heat pulse stimulation. They may provide diagnostic value; however, the possible...
OBJECTIVES
Paradoxical sensations, known as thermal pain illusions, can be evoked by painful cold-heat pulse stimulation. They may provide diagnostic value; however, the possible interaction between conditioned pain modulation and thermal pain illusions has not been explored. The present study examined: (1) whether conditioned pain modulation could be induced by alternating tonic painful cold-heat pulse stimulation; and (2) whether the presence of thermal pain illusions during the conditioning stimulus influences the degree of conditioned pain modulation.
METHODS
This study was approved by the Ethics Committee of Meikai University (A1507). Conditioned pain modulation was provoked using alternating painful cold-heat pulses delivered at 20-s intervals applied to the forearm. Thermal pain illusions were qualitatively evaluated, and conditioned pain modulation was assessed quantitatively using the pressure pain threshold as a test stimulus. Differences in the conditioned pain modulation effect between the participants who experienced thermal pain illusions and those who did not were analysed using Student's -test.
RESULTS
A significant positive conditioned pain modulation effect (51.0 ± 4.7%, overall effect) was detected. There was no significant difference in conditioned pain modulation between the participants who experienced thermal pain illusions and those who did not (44.3 ± 6.0% and 55.5 ± 6.8%, respectively; p = 0.255).
CONCLUSIONS
Conditioned pain modulation induced by alternating painful conditioning cold-heat pulse stimulation was identical during the conditioning stimulation in volunteers with and without thermal pain illusions. Conditioning cold-heat pulse stimulation is useful to evaluate conditioned pain modulation. Moreover, conditioned pain modulation is not influenced by the presence of thermal pain illusions, indicating partially different underlying supraspinal, neuronal networks.
Topics: Humans; Illusions; Pain Measurement; Pain; Pain Threshold; Hot Temperature
PubMed: 35607757
DOI: 10.1515/sjpain-2022-0037 -
The Clinical Journal of Pain Jan 2023Psychological trauma often co-occurs with pain. This relationship has been explored using laboratory pain measures; however, findings have been mixed. Previous studies... (Meta-Analysis)
Meta-Analysis
OBJECTIVES
Psychological trauma often co-occurs with pain. This relationship has been explored using laboratory pain measures; however, findings have been mixed. Previous studies have limited operationalization of trauma (eg, posttraumatic stress disorder) or pain (eg, pain thresholds), which may contribute to conflicting results. Further, prior reviews likely underrepresent trauma experiences among people who are not receiving clinical care, limiting generalizability.
MATERIALS AND METHODS
We systematically reviewed the existing literature on the relationship between psychological trauma (eg, car accidents, sexual assault, childhood abuse, neglect) and laboratory pain (ie, quantitative sensory testing measures of pain threshold, intensity, summation, modulation), using inclusive criteria. The direction of the relationship between psychological trauma and pain sensitivity was evaluated, and moderation by purported pain mechanism (ie, pain detection, suprathreshold pain, central sensitization, inhibition) was explored.
RESULTS
Analyses were conducted using 48 studies that provided 147 effect sizes. A multivariate random-effects model with robust variance estimation resulted in a small but statistically significant overall effect size of g=0.24 (P=0.0002), reflecting a positive association between psychological trauma and enhanced laboratory pain sensitivity. Upon examination of mechanistic moderators, this relationship appears driven by effects on pain detection (g=0.28, P=0.002) and central sensitization (g=0.22, P=0.04). While effect sizes were similar across all moderators, effects on suprathreshold pain and inhibition were not statistically significant.
DISCUSSION
Findings demonstrate an overall pattern of trauma-related pain enhancement and point to central sensitization as a key underlying mechanism.
Topics: Humans; Child; Life Change Events; Pain; Stress Disorders, Post-Traumatic; Pain Threshold; Central Nervous System Sensitization
PubMed: 36524769
DOI: 10.1097/AJP.0000000000001082 -
European Journal of Applied Physiology Oct 2022Acute physical activity leads to exercise-induced hypoalgesia (EIH). The aim of this study was to investigate the effects of four different exercise intensities on EIH. (Randomized Controlled Trial)
Randomized Controlled Trial
PURPOSE
Acute physical activity leads to exercise-induced hypoalgesia (EIH). The aim of this study was to investigate the effects of four different exercise intensities on EIH.
METHODS
25 male (age: 24.7 ± 3.0) subjects underwent four different exercise sessions on a bicycle ergometer for 30 min each at 60, 80, 100, and 110% of the individual anaerobic threshold on separate days in a randomized crossover design. Before, as well as 5- and 45-min post-exercise, pain sensitivity was measured employing pain pressure thresholds (PPT) at the elbow, knee, and ankle joints as well as the sternum and forehead. Besides, conditioned pain modulation (CPM) was conducted using thermal test- and conditioned stimuli before, 5-, and 45-min post-exercise.
RESULTS
A main time effect was observed regarding PPT at all landmarks except for the forehead with higher values observed 5 and 45 min post-exercise compared to the pre-values. Yet, no interaction effects occurred. CPM did not change in response to any of the intensities used.
CONCLUSION
EIH occurs 5 and 45 min after exercise regardless of the intensity used at the joints and sternum which might be explained by local pain-inhibiting pathways and probably to a limited degree by central mechanisms, as no hypoalgesia was observed at the forehead and no changes in CPM occurred.
Topics: Adult; Anaerobic Threshold; Cross-Over Studies; Humans; Male; Pain; Pain Measurement; Pain Perception; Pain Threshold; Young Adult
PubMed: 35809091
DOI: 10.1007/s00421-022-04997-1 -
Journal of Clinical Psychology in... Sep 2021This study examined factors that may enhance the relationship between resilience and time to pain threshold and tolerance during experimentally induced pain among 62...
This study examined factors that may enhance the relationship between resilience and time to pain threshold and tolerance during experimentally induced pain among 62 healthy adults recruited from a student population. Specifically, dispositional optimism and psychological grit were examined as moderators of the relationship between resilience and pain outcomes. Zero-order correlations revealed that resilience was positively related to grit and optimism, though grit and optimism were not significantly related to each other. Resilience, grit and optimism were all positively related to time to pain threshold and tolerance, but not pain severity. Moderation models showed that dispositional optimism enhanced the effect of resilience on both time to pain threshold and tolerance. Grit, on the other hand, was found to enhance the effect of resilience on time to pain threshold, but not time to pain tolerance. These results suggest that positive psychological factors and their interactions may be important with persevering during adverse experiences such as pain.
Topics: Adult; Humans; Optimism; Pain; Pain Threshold; Personality; Resilience, Psychological
PubMed: 32564216
DOI: 10.1007/s10880-020-09731-7 -
Osteoarthritis and Cartilage Jul 2015Emerging evidence suggests that pain sensitization plays an important role in pain associated with knee osteoarthritis (OA). This systematic review and meta-analysis... (Meta-Analysis)
Meta-Analysis Review
OBJECTIVE
Emerging evidence suggests that pain sensitization plays an important role in pain associated with knee osteoarthritis (OA). This systematic review and meta-analysis examined the evidence for pain sensitization in people with knee OA and the relationship between pain sensitization and symptom severity.
METHODS
A search of electronic databases and reference lists was carried out. All full text observational studies published between 2000 and 2014 with the aim of investigating pain sensitization in humans with knee OA using quantitative sensory testing (QST) measures of hyperalgesia and central hyperexcitability were eligible for inclusion. Meta-analysis of data was carried out using a random effects model, which included results comparing knee OA participants to controls, and results comparing high symptom severity to low symptom severity.
RESULTS
Fifteen studies were identified following screening and quality appraisal. For the meta-analysis, pressure pain threshold (PPT) and heat pain threshold (HPT) means and standard deviations were pooled using random effects models. The point estimate was large for differences in PPTs between knee OA participants and controls [-0.85; confidence interval (CI): -1.1 to -0.6], and moderate for PPT differences between knee OA participants with high symptom severity vs those with low symptom severity (0.51; CI: -0.73 to -0.30). A small point estimate was found for differences in HPTs between knee OA participants and controls (-0.42; CI: -0.87 to 0.02).
CONCLUSION
Evidence from this systematic review and meta-analysis suggests that pain sensitization is present in people with knee OA and may be associated with knee OA symptom severity.
Topics: Humans; Hyperalgesia; Osteoarthritis, Knee; Pain; Pain Measurement; Pain Threshold
PubMed: 25749012
DOI: 10.1016/j.joca.2015.02.163