Temporal Summation Of Heat Pain Research Articles

The influence of submaximal isometric exercise on temporal summation of heat pain

Numerous studies have indicated an attenuation of pain following exercise in healthy young adults, and this phenomenon has been referred to as exercise-induced hypoalgesia. Little is known, however, about the effect of short duration isometric exercise (i.e., static muscular contraction) on temporal summation of pain. Thus, the purpose of this study was to examine the influence of submaximal isometric exercise on the temporal summation of heat pain in men and women. Fifty-two men and women with a mean age of 21 yrs (sd = 3) participated in this study. Ten heat pulses were applied to the thenar eminence of the dominant hand using a standardized temporal summation protocol. Participants rated the intensity of the heat pulses using a 0-100 rating scale at baseline, before, and following isometric exercise which consisted of squeezing a hand dynamometer at 25% of maximum for 3 minutes. The data were analyzed with a 2 (sex) X 3 (trials: baseline, pre, and post) X 3 (pulses: 1, 5, and 10) repeated measures ANOVA. The results indicated a significant reduction (p < 0.05) in pain ratings following isometric exercise. The magnitude of reduction in temporal summation of heat pain was moderate (effect sizes for the men = 0.37-0.40 and for the women = 0.57-0.64). It is concluded that short duration, submaximal isometric exercise was associated with a reduction in temporal summation of heat pain in men and women. Supported by NIH grant R21AR057159. Numerous studies have indicated an attenuation of pain following exercise in healthy young adults, and this phenomenon has been referred to as exercise-induced hypoalgesia. Little is known, however, about the effect of short duration isometric exercise (i.e., static muscular contraction) on temporal summation of pain. Thus, the purpose of this study was to examine the influence of submaximal isometric exercise on the temporal summation of heat pain in men and women. Fifty-two men and women with a mean age of 21 yrs (sd = 3) participated in this study. Ten heat pulses were applied to the thenar eminence of the dominant hand using a standardized temporal summation protocol. Participants rated the intensity of the heat pulses using a 0-100 rating scale at baseline, before, and following isometric exercise which consisted of squeezing a hand dynamometer at 25% of maximum for 3 minutes. The data were analyzed with a 2 (sex) X 3 (trials: baseline, pre, and post) X 3 (pulses: 1, 5, and 10) repeated measures ANOVA. The results indicated a significant reduction (p < 0.05) in pain ratings following isometric exercise. The magnitude of reduction in temporal summation of heat pain was moderate (effect sizes for the men = 0.37-0.40 and for the women = 0.57-0.64). It is concluded that short duration, submaximal isometric exercise was associated with a reduction in temporal summation of heat pain in men and women. Supported by NIH grant R21AR057159.

Greater dispositional optimism is related to diminished temporal summation of heat pain in older adults with knee pain with and without radiographic evidence of knee osteoarthritis

Existing evidence suggests that personality factors can influence individuals' responses to pain. Of interest, dispositional optimism has been related to diminished pain sensitivity and adaptive pain responses. One explanation for the beneficial contributions of dispositional optimism to the pain experience is that optimism is associated with endogenous pain processing mechanisms. Our group has previously shown that greater dispositional optimism was associated with enhanced endogenous pain-inhibitory processes,1 yet it remains to be tested whether dispositional optimism is also inversely related with pain facilitatory processes such as temporal summation (TS) of pain, a presumed perceptual manifestation of enhanced central excitability.

Pain Sensitivity Risk Factors for Chronic TMD: Descriptive Data and Empirically Identified Domains from the OPPERA Case Control Study

Many studies report that people with temporomandibular disorders (TMD) are more sensitive to experimental pain stimuli than TMD-free controls. Such differences in sensitivity are observed in remote body sites as well as in the orofacial region, suggesting a generalized upregulation of nociceptive processing in TMD cases. This large case-control study of 185 adults with TMD and 1,633 TMD-free controls measured sensitivity to painful pressure, mechanical cutaneous, and heat stimuli, using multiple testing protocols. Based on an unprecedented 36 experimental pain measures, 28 showed statistically significantly greater pain sensitivity in TMD cases than controls. The largest effects were seen for pressure pain thresholds at multiple body sites and cutaneous mechanical pain threshold. The other mechanical cutaneous pain measures and many of the heat pain measures showed significant differences, but with lesser effect sizes. Principal component analysis (PCA) of the pain measures derived from 1,633 controls identified 5 components labeled: 1) heat pain ratings; 2) heat pain aftersensations and tolerance; 3) mechanical cutaneous pain sensitivity; 4) pressure pain thresholds; and 5) heat pain temporal summation. These results demonstrate that compared to TMD-free controls, chronic TMD cases are more sensitive to many experimental noxious stimuli at extracranial body sites, and provide for the first time the ability to directly compare the case-control effect sizes of a wide range of pain sensitivity measures. Perspective This article describes experimental pain sensitivity differences between a large sample of people with chronic TMD and non-TMD controls, using multiple stimulus modalities and measures. Variability in the magnitude and consistency of case-control differences highlight the need to consider multiple testing measures to adequately assess pain processing alterations in chronic pain conditions.

Alterations in pain responses in treated and untreated patients with restless legs syndrome: Associations with sleep disruption

Objective There has been recent interest in characterizing potential abnormalities of pain processing in patients with sleep disorders such as Restless Legs Syndrome (RLS). The aim of this study was to evaluate psychophysical responses to noxious heat and pressure stimuli in both treated and untreated RLS patients, compared to matched controls. Methods This study is a cross-sectional group comparison of RLS patients with matched controls. A total of 31 patients (15 treated, 16 untreated) with a confirmed diagnosis of RLS were compared to 18 controls with no history of RLS or related sleep disorders. Results RLS patients (both treated and untreated) demonstrated reduced pain thresholds and reported greater clinical pain relative to controls. Moreover, RLS patients demonstrated enhanced temporal summation of heat pain ( p < .05), which may reflect aberrant central nervous system facilitation of pain transmission. Both treated and untreated RLS patients reported disrupted sleep relative to controls, and mediation analyses suggested that the reduced pain thresholds in RLS were attributable to sleep disturbance. However, the effect of RLS on the magnitude of temporal summation of heat pain was independent of sleep disturbance. Conclusions These findings suggest that central nervous system pain processing may be amplified in RLS, perhaps partially as a consequence of sleep disruption. RLS patients, even those whose symptoms are managed pharmacologically, may be at elevated long-term risk for the development or maintenance of persistent pain conditions. Further studies in larger samples could help to improve the prospects for pain management in RLS patients.

Temporal summation in women with TMJD compared with Healthy controls: Associations with Sleep quality and impaired physical activity

Quality of sleep has been associated with physical functioning and disability in chronic pain patients. However the relations between endogenous pain modulation, sleep quality and disability in women with TMJD is not known. The goal of this study was to analyze the association of temporal summation of heat pain with disability and sleep quality in women with TMJD and healthy controls. A total of 55 women (30 TMJD, 25 controls) were enrolled in the study. All participants were screened over the phone. Eligible participants completed a clinical visit, which included psychological questionnaires, clinical examination and sensory tests (pressure, thermal and ischemic pain procedures), including temporal summation of heat pain. The statistical analyses included ANOVA and Regression. Our results indicated that TMJD women had greater sensitivity to temporal summation than controls at 46⁰C (p=0.012), 48⁰C (p=0.047) and borderline significance at 50⁰C (p=0.052). However, these group differences should be interpreted in light of a significant interaction between sleep quality and group, such that TMJD women who had poor quality of sleep had significantly elevated temporal summation at 46⁰C than control women (p=0.045). However, no group difference in temporal summation emerged for women with good sleep quality (p > 0.10). Regarding disability, temporal summation at 46⁰C was significantly and positively associated with reports of physical activity-related interference (p=0.031) in the TMJD group, after controlling for negative affect and clinical pain. TMJD women are more sensitive to temporal summation than controls, and this association appears to me moderated by sleep quality. Sleep dysfunction may increase temporal summation of pain in women with TMJD, which in turn may be associated with greater pain-related interference among women with TMJD. Quality of sleep has been associated with physical functioning and disability in chronic pain patients. However the relations between endogenous pain modulation, sleep quality and disability in women with TMJD is not known. The goal of this study was to analyze the association of temporal summation of heat pain with disability and sleep quality in women with TMJD and healthy controls. A total of 55 women (30 TMJD, 25 controls) were enrolled in the study. All participants were screened over the phone. Eligible participants completed a clinical visit, which included psychological questionnaires, clinical examination and sensory tests (pressure, thermal and ischemic pain procedures), including temporal summation of heat pain. The statistical analyses included ANOVA and Regression. Our results indicated that TMJD women had greater sensitivity to temporal summation than controls at 46⁰C (p=0.012), 48⁰C (p=0.047) and borderline significance at 50⁰C (p=0.052). However, these group differences should be interpreted in light of a significant interaction between sleep quality and group, such that TMJD women who had poor quality of sleep had significantly elevated temporal summation at 46⁰C than control women (p=0.045). However, no group difference in temporal summation emerged for women with good sleep quality (p > 0.10). Regarding disability, temporal summation at 46⁰C was significantly and positively associated with reports of physical activity-related interference (p=0.031) in the TMJD group, after controlling for negative affect and clinical pain. TMJD women are more sensitive to temporal summation than controls, and this association appears to me moderated by sleep quality. Sleep dysfunction may increase temporal summation of pain in women with TMJD, which in turn may be associated with greater pain-related interference among women with TMJD.

Ethnic differences in temporal summation of thermal pain

Temporal summation of thermal pain is a frequently implemented dynamic laboratory pain induction technique. However, methodological and analytical techniques vary across studies resulting in a diverse array of findings and limited inter-study comparability. The purpose of this study was to evaluate analytic and interpretive differences in temporal summation of heat pain in a sample of ethnically diverse healthy adults. Participants included 100 African American (AA), 102 non-Hispanic white (NHW), and 94 Hispanic (H) individuals who completed two experimental sessions of laboratory pain stimuli including thermal, ischemic, mechanical, and cold.

Anesthesia Literature Review

Anesthesia Literature Review

Temporal summation of heat pain in humans: Evidence supporting thalamocortical modulation

Noxious cutaneous contact heat stimuli (48 °C) are perceived as increasingly painful when the stimulus duration is extended from 5 to 10 s, reflecting the temporal summation of central neuronal activity mediating heat pain. However, the sensation of increasing heat pain disappears, reaching a plateau as stimulus duration increases from 10 to 20 s. We used functional magnetic resonance imaging (fMRI) in 10 healthy subjects to determine if active central mechanisms could contribute to this psychophysical plateau. During heat pain durations ranging from 5 to 20 s, activation intensities in the bilateral orbitofrontal cortices and the activation volume in the left primary (S1) somatosensory cortex correlated only with perceived stimulus intensity and not with stimulus duration. Activation volumes increased with both stimulus duration and perceived intensity in the left lateral thalamus, posterior insula, inferior parietal cortex, and hippocampus. In contrast, during the psychophysical plateau, both the intensity and volume of thalamic and cortical activations in the right medial thalamus, right posterior insula, and left secondary (S2) somatosensory cortex continued to increase with stimulus duration but not with perceived stimulus intensity. Activation volumes in the left medial and right lateral thalamus, and the bilateral mid-anterior cingulate, left orbitofrontal, and right S2 cortices also increased only with stimulus duration. The increased activity of specific thalamic and cortical structures as stimulus duration, but not perceived intensity, increases is consistent with the recruitment of a thalamocortical mechanism that participates in the modulation of pain-related cortical responses and the temporal summation of heat pain.

Catechol- O-methyltransferase gene polymorphisms are associated with multiple pain-evoking stimuli

Variations in the gene encoding catechol- O-methyltransferase ( COMT) are linked to individual differences in pain sensitivity. A single nucleotide polymorphism (SNP) in codon 158 ( val 158 met), which affects COMT protein stability, has been associated with the human experience of pain. We recently demonstrated that three common COMT haplotypes, which affect the efficiency of COMT translation, are strongly associated with a global measure of pain sensitivity derived from individuals’ responses to noxious thermal, ischemic, and pressure stimuli. Specific haplotypes were associated with low (LPS), average (APS), or high (HPS) pain sensitivity. Although these haplotypes included the val 158 met SNP, a significant association with val 158 met variants was not observed. In the present study, we examined the association between COMT genotype and specific pain-evoking stimuli. Threshold and tolerance to thermal, ischemic, and mechanical stimuli, as well as temporal summation to heat pain, were determined. LPS/LPS homozygotes had the least, APS/APS homozygotes had average, and APS/HPS heterozygotes had the greatest pain responsiveness. Associations were strongest for measures of thermal pain. However, the rate of temporal summation of heat pain did not differ between haplotype combinations. In contrast, the val 158 met genotype was associated with the rate of temporal summation of heat pain, but not with the other pain measures. This suggests that the val 158 met SNP plays a primary role in variation in temporal summation of pain, but that other SNPs of the COMT haplotype exert a greater influence on resting nociceptive sensitivity. Here, we propose a mechanism whereby these two genetic polymorphisms differentially affect pain perception.

Is Self-Reported Childhood Abuse History Associated With Pain Perception Among Healthy Young Women and Men?

A self-reported history of childhood physical and/or sexual abuse is frequently reported among chronic pain populations and has been associated with poorer adjustment to pain. In addition, self-reported abuse history has been related to increased pain complaints in population-based studies. One possible explanation for the association between abuse and clinical pain is that abuse victims may display enhanced sensitivity to painful stimuli, which increases the risk of developing clinical pain. However, the limited evidence addressing this issue has been mixed. The purpose of this study was to examine the association between self-reported history of childhood sexual or physical abuse and experimental pain responses in a nonclinical sample of generally healthy young adults. Participants were 110 (56 female, 54 male) college students who completed a series of questionnaires assessing abuse history, recent pain, health care utilization, perceived health, and psychologic variables. Also, measures of thermal and ischemic pain threshold and tolerance were obtained in all participants. In addition, a procedure assessing temporal summation of heat pain was conducted in which intensity and unpleasantness ratings of repetitive thermal stimuli were obtained. Systolic and diastolic blood pressure and heart rate were assessed at resting and during the ischemic pain task. Participants with a positive childhood abuse history were oversampled, yielding 21 out of 56 (37.5%) women with a positive history of abuse and 13 out of 54 (24.1%) PHA men. No abuse group differences emerged for thermal or ischemic pain thresholds or tolerances (P values>0.05). However, compared to women with no childhood abuse history, women with a positive history of abuse provided significantly lower average pain unpleasantness and peak pain unpleasantness ratings and lower unpleasantness ratings of the first trial during the temporal summation procedure, whereas no abuse group differences emerged for men. Also, compared to participants with no childhood abuse history, participants of both genders with a positive history of abuse demonstrated smaller increases (ie, less temporal summation) in pain unpleasantness ratings across trials of thermal stimulation, and participants with a positive history of abuse showed greater decreases in pain intensity and unpleasantness after reaching their peak pain level (ie, greater wind-down) compared to participants with no childhood abuse history. In addition, participants with a positive history of abuse reported more sites of recent pain, poorer perceived health, greater somatization, and more negative affect. No group differences in resting cardiovascular measures or cardiovascular reactivity were observed. These findings indicate that a self-reported history of childhood abuse is associated with decreased sensitivity to experimentally induced pain, especially among women. However, abuse history was associated with increased pain complaints, poorer self-reported health, and greater negative affect. These data highlight the complexity of the relationship between abuse history and pain and illustrate the need for further investigation of potential pain-related correlates of abuse.

Associations Among Four Modalities of Experimental Pain in Women

The aim of this study was to investigate the associations among 4 measures of pain induction procedures in 244 healthy women. The procedures were (1) pressure pain threshold assessed over the temporalis muscles, masseter muscles, temporomandibular joints, and the wrists; (2) C fiber–mediated heat pain threshold/tolerance assessed on the skin over the forearm, cheek, and dorsal aspect of the foot; (3) temporal summation of C fiber–mediated heat pain; and (4) ischemic pain threshold/tolerance. Strong associations among pressure pain thresholds at the 4 sites examined (ρ = 0.7 to 0.8, P values ≤ .001) and among heat pain threshold/tolerance values at the 3 sites examined (ρ = 0.6 to 0.9, P values ≤ .001) were observed. Pressure pain threshold was moderately correlated with each of the heat pain threshold/tolerance values (ρ = 0.2 to 0.4, P values ≤ .001). Ischemic pain threshold/tolerance was moderately associated with each of the pressure and heat pain measures (ρ = 0.2 to 0.3, P values ≤ .05 to .001). Derived measures of the temporal summation of heat pain did not correlate strongly with threshold or tolerance measures of pressure, ischemic, or heat pain. We concluded (1) that for a specific pain modality, the correlation between threshold and tolerance values across anatomic sites is high, and (2) that measures of pressure, ischemic, and thermal pain threshold/tolerance are significantly correlated, although the strength of these associations is moderate. These findings demonstrate that a battery of pain-assessing procedures is required to determine an individual’s pain sensitivity profile or phenotype. Perspective By investigating the relationship between pain sensitivity produced by different forms of stimuli, this study demonstrates that a battery of tests should be used to assess an individual’s pain sensitivity and one should be careful in making inferences about an individual’s sensitivity to pain by using only one pain modality.

Cluster analysis of multiple experimental pain modalities

Identifying individual differences in pain is an important topic; however, little is known regarding patterns of responses across various experimental pain modalities. This study evaluated subgroups emerging from multiple experimental pain measures. One hundred and eighty-eight individuals (59.0% female) completed several psychological instruments and underwent ischemic, pressure, and thermal pain assessments. Thirteen separate pain measures were obtained by using three experimental pain modalities with several parameters tested within each modality. The pain ratings and scores were submitted to factor analysis that identified four pain factors from which Pain Sensitivity Index (PSI) scores were computed: heat pain (HP), pressure pain (PP), ischemic pain (IP), and temporal summation of heat pain (TS). Cluster analyses of PSI scores revealed four distinct clusters. The first cluster demonstrated high overall pain sensitivity, the second cluster revealed high TS, the third cluster showed particular insensitivity to IP and low sensitivity across pain modalities except PP, and the fourth cluster demonstrated low sensitivity to PP. Significant correlations were found between psychological measures and Index scores and those differed by sex. Cluster membership was associated with demographic variables of ethnicity and sex as well as specific psychosocial variables, although cluster differences were only partially explained by such factors. These analyses revealed that groups respond differently across varied pain stimuli, and this was not related solely to demographic or psychosocial factors. These findings highlight the need for future investigation to identify patterns of responses across different pain modalities in order to more accurately characterize individual differences in responses to experimental pain.

Age effects on pain thresholds, temporal summation and spatial summation of heat and pressure pain

Experimental data on age-related changes in pain perception have so far been contradictory. It has appeared that the type of pain induction method is critical in this context, with sensitivity to heat pain being decreased whereas sensitivity to pressure pain may be even enhanced in the elderly. Furthermore, it has been shown that temporal summation of heat pain is more pronounced in the elderly but it has remained unclear whether age differences in temporal summation are also evident when using other pain induction methods. No studies on age-related changes in spatial summation of pain have so far been conducted. The aim of the present study was to provide a comprehensive survey on age-related changes in pain perception, i.e. in somatosensory thresholds (warmth, cold, vibration), pain thresholds (heat, pressure) and spatial and temporal summation of heat and pressure pain. We investigated 20 young (mean age 27.1 years) and 20 elderly (mean age 71.6 years) subjects. Our results confirmed and extended previous findings by showing that somatosensory thresholds for non-noxious stimuli increase with age whereas pressure pain thresholds decrease and heat pain thresholds show no age-related changes. Apart from an enhanced temporal summation of heat pain, pain summation was not found to be critically affected by age. The results of the present study provide evidence for stimulus-specific changes in pain perception in the elderly, with deep tissue (muscle) nociception being affected differently by age than superficial tissue (skin) nociception. Summation mechanisms contribute only moderately to age changes in pain perception.

Temporal summation of heat pain: A psychophysical analysis

Temporal summation of heat pain: A psychophysical analysis

MULTIDISCIPLINARY PAIN ABSTRACTS: 22 . Neurology (22)

Temporal summation of heat pain during repetitive stimulation is dependent on C nociceptor activation of central N‐methyl‐D‐aspartate (NMDA) receptor mechanisms. Moderate temporal summation is produced by sequential triangular ramps of stimulation that control skin temperature between heat pulses but do not elicit distinct first and second pain sensations. Dramatic summation of second pain is produced by repeated contact of the skin with a preheated thermode, but skin temperature between taps is not controlled by this procedure. Therefore, relationships between recordings of skin temperature and psychophysical ratings of heat pain were evaluated during a series of repeated skin contacts. The conclusion was that the magnitude of aching pain was well related to skin temperature and thus appeared to be established primarily by peripheral factors.

Relationships between skin temperature and temporal summation of heat and cold pain.

Temporal summation of heat pain during repetitive stimulation is dependent on C nociceptor activation of central N-methyl-d-aspartate (NMDA) receptor mechanisms. Moderate temporal summation is produced by sequential triangular ramps of stimulation that control skin temperature between heat pulses but do not elicit distinct first and second pain sensations. Dramatic summation of second pain is produced by repeated contact of the skin with a preheated thermode, but skin temperature between taps is not controlled by this procedure. Therefore relationships between recordings of skin temperature and psychophysical ratings of heat pain were evaluated during series of repeated skin contacts. Surface and subcutaneous recordings of skin temperatures revealed efficient thermoregulatory compensation for heat stimulation at interstimulus intervals (ISIs) ranging from 2 to 8 s. Temporal summation of heat pain was strongly influenced by the ISIs and cannot be explained by small increases in skin temperature between taps or by heat storage throughout a stimulus series. Repetitive brief contact with a precooled thermode was utilized to evaluate whether temporal summation of cold pain occurs, and if so, whether it is influenced by skin temperature. Surface and subcutaneous recordings of skin temperature revealed a sluggish thermoregulatory compensation for repetitive cold stimulation. In contrast to heat stimulation, skin temperature did not recover between cold stimuli throughout ISIs of 3-8 s. Psychophysically, repetitive cold stimulation produced an aching pain sensation that progressed gradually and radiated beyond the site of stimulation. The magnitude of aching pain was well related to skin temperature and thus appeared to be established primarily by peripheral factors.

Gender differences in temporal summation of mechanically evoked pain

Several studies indicate that females are more sensitive to experimentally induced pain than males. Moreover, it was recently shown that temporal summation of heat pain is greater in females than males, suggesting that central processing of nociceptive input may be upregulated in women. Temporal summation of pain has been examined principally using thermal or electrical stimuli. The purpose of this study was to investigate the temporal summation to noxious mechanical stimulation, and examine gender differences in temporal summation of mechanically evoked pain. A sharp probe was used to apply brief mechanical stimuli on the fingers of ten healthy females and ten healthy males. Trains of ten repetitive stimuli were applied at an intensity of 1.2–1.3× the individual subject's pain threshold, at interstimulus intervals (ISIs) ranging from 1 to 6 s. The same or different skin sites were stimulated in any single train of stimuli. The pain ratings for the fifth as well as the tenth stimulus were significantly higher than those for the first stimulus. Also, the pain responses for the tenth stimulus were higher than those for the fifth. There was no overall gender difference in pain ratings, however, there was a significant trial #×gender interaction. Males and females provided comparable magnitude estimates for the first stimulus in the train, but females provided higher pain ratings than males for the fifth as well as the tenth stimulus. Temporal summation occurred across all ISIs, but shorter ISIs (1–3 s) elicited significantly greater temporal summation than longer ISIs (4–6 s). Finally, although higher pain ratings were obtained when the ten consecutive stimuli were applied on the same versus different skin areas, the degree of temporal summation was not significantly different. These findings indicate that temporal summation of mechanically evoked pain is higher in females compared to males, is stimulation frequency dependent and is centrally mediated.