Emotional modulation of pain and spinal nociception in fibromyalgia

Fibromyalgia (FM) is characterized by widespread pain, as well as affective disturbance (eg, depression). Given that emotional processes are known to modulate pain, a disruption of emotion and emotional modulation of pain and nociception may contribute to FM. The present study used a well-validated affective picture-viewing paradigm to study emotional processing and emotional modulation of pain and spinal nociception. Participants were 18 individuals with FM, 18 individuals with rheumatoid arthritis (RA), and 19 healthy pain-free controls (HC). Mutilation, neutral, and erotic pictures were presented in 4 blocks; 2 blocks assessed only physiological-emotional reactions (ie, pleasure/arousal ratings, corrugator electromyography, startle modulation, skin conductance) in the absence of pain, and 2 blocks assessed emotional reactivity and emotional modulation of pain and the nociceptive flexion reflex (NFR, a physiological measure of spinal nociception) evoked by suprathreshold electric stimulations over the sural nerve. In general, mutilation pictures elicited displeasure, corrugator activity, subjective arousal, and sympathetic activation, whereas erotic pictures elicited pleasure, subjective arousal, and sympathetic activation. However, FM was associated with deficits in appetitive activation (eg, reduced pleasure/arousal to erotica). Moreover, emotional modulation of pain was observed in HC and RA, but not FM, even though all 3 groups evidenced modulation of NFR. Additionally, NFR thresholds were not lower in the FM group, indicating a lack of spinal sensitization. Together, these results suggest that FM is associated with a disruption of supraspinal processes associated with positive affect and emotional modulation of pain, but not brain-to-spinal cord circuitry that modulates spinal nociceptive processes.     

Emotional modulation of pain and spinal nociception in persons with major depressive disorder (MDD)

Major depressive disorder (MDD) is associated with risk for chronic pain, but the mechanisms contributing to the MDD and pain relationship are unclear. To examine whether disrupted emotional modulation of pain might contribute, this study assessed emotional processing and emotional modulation of pain in healthy controls and unmedicated persons with MDD (14 MDD, 14 controls). Emotionally charged pictures (erotica, neutral, mutilation) were presented in 4 blocks. Two blocks assessed physiological-emotional reactions (pleasure/arousal ratings, corrugator electromyography (EMG), startle modulation, skin conductance) in the absence of pain and 2 blocks assessed emotional modulation of pain and the nociceptive flexion reflex (NFR, a physiological measure of spinal nociception) evoked by suprathreshold electric stimulations. Results indicated pictures generally evoked the intended emotional responses; erotic pictures elicited pleasure, subjective arousal, and smaller startle magnitudes, whereas mutilation pictures elicited displeasure, corrugator EMG activation, and subjective/physiological arousal. However, emotional processing was partially disrupted in MDD, as evidenced by a blunted pleasure response to erotica and a failure to modulate startle according to a valence linear trend. Furthermore, emotional modulation of pain was observed in controls but not MDD, even though there were no group differences in NFR threshold or emotional modulation of NFR. Together, these results suggest supraspinal processes associated with emotion processing and emotional modulation of pain may be disrupted in MDD, but brain to spinal cord processes that modulate spinal nociception are intact. Thus, emotional modulation of pain deficits may be a phenotypic marker for future pain risk in MDD.     

The modulation of pain by attention and emotion: A dissociation of perceptual and spinal nociceptive processes

Emotions and attention have been shown to influence the perception of pain and several psychophysiological studies have suggested an implication of descending modulatory mechanisms to explain these effects. However, the specificity of the neurophysiological mechanisms underlying the emotional and attentional modulation of pain still remains unclear. In order to differentiate the supra‐spinal and spinal mechanisms involved in emotional and attentional modulation of pain, we measured pain perception (self‐ratings) and the RIII reflex in healthy volunteers during the presentation of pleasant, unpleasant and neutral pictures, as well as during a baseline condition with no visual distractor (Experiment 1). In a second experiment, we manipulated the emotional arousal induced by pleasant and unpleasant pictures in order to compare more directly the effects of distraction and arousal. Whereas emotional valence influenced pain and the amplitude of the RIII reflex in the same direction (negative>positive), distraction by neutral pictures reduced pain but increased the RIII reflex relative to baseline. Increased arousal further potentiated the effects of negative valence on both pain and the RIII reflex and the effects of positive emotions on pain, as previously reported. However, arousal did not potentiate the inhibitory effect of positive pictures on the RIII and seems insufficient to account for the effect of distraction on the RIII. Overall, these data provide further evidence that attention and emotion modulate pain through partially dissociable neurophysiological mechanisms.     

Fear of Pain in Recurrent Headache Sufferers

We investigated the role of fear of pain in headache sufferers using the Fear of Pain Questionnaire (FPQ). Seventy-six headache sufferers and 58 controls completed the FPQ and measures of depression, anxiety, and anger. Headache sufferers also completed measures of stress-related physical symptoms and coping with pain. We found that the FPQ has excellent internal consistency as well as good concurrent and construct validity indicated by the high correlations between the FPQ subscales and both anxiety and depression but low correlations with anger. There were marked differences between headache sufferers and controls on the FPQ; headache sufferers showed much greater fear of severe and medical pain and lower fear of minor pain. Fear of pain was generally not related to headache characteristics such as frequency, severity, or duration. On the other hand, it was related to headache impact such as disruption of pleasurable activities. These results are consistent with models of chronic pain disorders which emphasize the role of fear of pain over the nociceptive intensity of the pain stimulus.     

The effect of the menstrual cycle on affective modulation of pain and nociception in healthy women

Research indicates pain may be influenced by the menstrual cycle. While the mechanisms underlying these effects are unclear, it is possible that menstrual phase-related changes in endogenous pain modulation contribute. The present study used well-validated methods to study affective modulation of pain and the nociceptive flexion reflex (NFR) in healthy women during two menstrual phases (mid-follicular vs. late-luteal). Women (N = 41) tracked their menstrual phases for three complete cycles and were asked to attend two laboratory testing sessions in the second and third cycles to assess affective modulation of pain and nociception (testing order counterbalanced). Menstrual phase was assessed from daily diaries, luteinizing hormone tests, and basal body temperature. At each session, emotionally charged pictures were presented and suprathreshold electrocutaneous stimulations were delivered during and in between pictures. Subjective and physiological emotional reactions were recorded in response to each picture and pain ratings and NFRs were recorded in response to each suprathreshold stimulus. Results suggested pictures effectively manipulated emotion in both menstrual phases. Moreover, arousing unpleasant pictures enhanced pain and NFR, whereas arousing pleasant pictures inhibited pain and NFR. These modulatory effects were similar in both menstrual phases. Together, these findings suggest that affective engagement of corticospinal mechanisms does not differ across these phases of the menstrual cycle. However, future research is needed to directly assess the relationship between affective modulation of pain/nociception and inter- and intra-individual differences in ovarian hormones and to extend these findings to women who suffer from menstrual cycle-related pain (e.g., premenstrual dysphoric disorder, fibromyalgia).     

The Fear of Pain questionnaire: factor structure in samples of young, middle-aged and elderly European people.

The present study examined the factor structure of the Fear of Pain questionnaire in three independent samples composed of European young adults, middle-aged, and elderly people. Seven hundred and thirty one adults (426 females and 305 males) were presented with the French adaptation of the questionnaire (30 items) and with an Exposure to Painful Situations questionnaire that contained the same items as the Fear of Pain questionnaire and where participants were instructed to indicate all the painful situations they have experienced in the past. When tested on the whole set of 30 items, the correlated three-factor model evidenced in previous studies - Severe pain, Minor pain and Medical pain - poorly fit the data. When tested on a set of 15 two-item parcels, the fit of this model was much better but the correlations between factors were very high. When tested on a reduced set of 15 items, the model fit the data as well as when it was tested on the set of 15 parcels, and the correlations between the three factors were lower. The study also examined the link between previous exposure to pain and fear of pain. The hypothesis that previous "natural" exposure to pain should generally result in a decrease in fear of pain was supported by the data. For 14 items, the exposure effect was moderate to strong.     

Fear of pain associated with medical procedures and illnesses.

The study was aimed at determining the dimensions of fear of pain associated with medical procedures and the dimensions of fear of pain associated with illnesses and accidents on a sample composed of young, middle-aged and elderly persons. The participants were 573 adults (aged 26-94 years). They were presented with (a) the French adaptation of the ten medical fear items from the original FPQ plus 19 additional items, (b) the French adaptation of the 6 illness items from the original FPQ plus 49 additional items, and (c) an Exposure to Painful Situations Questionnaire. As regards the fear of medical procedures, a four-factor structure was identified: Examination and Care, Shots, Dental care, and Invasive procedures. Older participants, and less educated participants tended to show more fear of invasive procedures than younger participants, and more educated participants. As regards the fear of pain associated with illnesses, an eight-factor solution was found: Minor ailments, cramps, infections and abscesses, inflamed joints, colics, breaks, lesion of organs, and cancer and terminal illness. Older participants tended to show more fear of pain associated with minor ailments, inflamed joints, breaks, colic, and cramps than younger participants did. Previous exposure to pain resulted in a clear decrease in fear of pain associated with most of medical procedures, especially invasive procedures and shots.     

Pain-related anxiety influences pain perception differently in men and women: A quantitative sensory test across thermal pain modalities

The sexes differ with respect to perception of experimental pain. Anxiety influences pain perception more in men than in women; however, there lacks research exploring which anxiety constructs influence pain perception differentially between men and women. Furthermore, research examining whether depression is associated with pain perception differently between the sexes remains scant. The present investigation was designed to examine how trait anxiety, pain-related anxiety constructs (ie, fear of pain, pain-related anxiety, anxiety sensitivity), and depression are associated with pain perception between the sexes. A total of 95 nonclinical participants (55% women) completed measures assessing the constructs of interest and participated in quantitative sensory testing using heat and cold stimuli administered by a Medoc Pathway Pain and Sensory Evaluation System. The findings suggest that pain-related anxiety constructs, but not trait anxiety, are associated with pain perception. Furthermore, these constructs are associated with pain intensity ratings in men and pain tolerance levels in women. This contrasts with previous research suggesting that anxiety influences pain perception mostly or uniquely in men. Depression was not systematically associated with pain perception in either sex. Systematic relationships were not identified that allow conclusions regarding how fear of pain, pain-related anxiety, and anxiety sensitivity may contribute to pain perception differentially in men and women; however, anxiety sensitivity was associated with increased pain tolerance, a novel finding needing further examination. The results provide directions for future research and clinical endeavors and support that fear and anxiety are important features associated with hyperalgesia in both men and women.     

The influence of children's pain memories on subsequent pain experience

Healthy children are often required to repeatedly undergo painful medical procedures (eg, immunizations). Although memory is often implicated in children's reactions to future pain, there is a dearth of research directly examining the relationship between the 2. The current study investigated the influence of children's memories for a novel pain stimulus on their subsequent pain experience. One hundred ten healthy children (60 boys) between the ages of 8 and 12 years completed a laboratory pain task and provided pain ratings. Two weeks later, children provided pain ratings based on their memories as well as their expectancies about future pain. One month following the initial laboratory visit, children again completed the pain task and provided pain ratings. Results showed that children's memory of pain intensity was a better predictor of subsequent pain reporting than their actual initial reporting of pain intensity, and mediated the relationship between initial and subsequent pain reporting. Children who had negatively estimated pain memories developed expectations of greater pain prior to a subsequent pain experience and showed greater increases in pain ratings over time than children who had accurate or positively estimated pain memories. These findings highlight the influence of pain memories on healthy children's expectations of future pain and subsequent pain experiences and extend predictive models of subsequent pain reporting.     

The influence of fear of movement and pain catastrophizing on daily pain and disability in individuals with acute whiplash injury: a daily diary study

Previous research supports the fear-avoidance model in explaining the transition from acute to chronic non-specific musculoskeletal pain. However, there is still little knowledge on when this vicious circle of pain, disability, pain catastrophizing and fear of movement starts. We performed a daily diary study in 42 patients with acute whiplash injury. Pain, disability, pain catastrophizing and fear of movement were measured on a daily basis with paper diaries for 21 consecutive days. Most participants showed a decline in pain and disability from day 1 to day 21 and this was paralleled by a decline in the fear of movement and pain catastrophizing. Multilevel analyses showed that both between and within persons, high levels of pain catastrophizing and fear of movement are associated with more pain and disability. Moreover, the fear of movement was also predictive of pain and disability on the following day. We also examined the reverse association, that is, whether the changes in pain predict changes in the next day's fear of movement and pain catastrophizing. Although for the fear of movement the model reached significance, the amount of explained variance was negligible. In conclusion, this study provides evidence that already in the early stages of whiplash-related complaints, significant associations between fear of movement and pain intensity and disability occur, and that this association may be predictive of the persistence of pain.     

Children's catastrophic thinking about their pain predicts pain and disability 6 months later

Catastrophic thinking about pain has been identified as an important determinant of adjustment to pain, in both adults and children. No study has investigated the prospective and unique role of catastrophizing in explaining later pain and disability in children. The aim of the present study was to investigate the prospective roles of catastrophic thinking about pain, pain intensity, and trait anxiety and their putative relationship with pain and disability tested 6 months later. Participants were 323 schoolchildren. Analyses revealed that the child's pain catastrophizing at baseline had a small but unique contribution to the prediction of pain and disability 6 months later, even when controlling for the initial pain and disability levels. In line with expectations, moderation analyses revealed that the effects of catastrophizing upon pain and disability at follow‐up were only true for those children reporting low levels intensity of pain at baseline. The variability in disability and pain complaint could not be explained by trait anxiety. Instead anxious disposition might be best conceived of as a precursor of catastrophizing in children; i.e. children with higher levels of trait anxiety at baseline were more inclined to report higher levels of catastrophizing at follow‐up. The findings are discussed in terms of potential mechanisms through which catastrophizing might exert its negative impact upon pain and disability outcomes in children.     

The multilevel organization of vicarious pain responses: effects of pain cues and empathy traits on spinal nociception and acute pain

The shared-representation model of empathy suggests that vicarious pain processes rely partly on the activation of brain systems underlying self-pain in the observer. Here, we tested the hypothesis that self-pain may be facilitated by the vicarious priming of neural systems underlying pain perception. Pictures illustrating painful agents applied to the hand or the foot (sensory information), or painful facial expressions (emotional information) were shown to 43 participants to test the effects of vicarious pain on the nociceptive flexion reflex (NFR) of the lower limb and pain intensity and unpleasantness produced by transcutaneous electrical stimulation applied over the sural nerve. Results confirmed the expected priming effects of vicarious pain on spinal and perceptual processes. However, for comparable pain intensity and arousal evoked by the pain pictures, the facilitation of the NFR and the self-pain unpleasantness measurements was more robust in response to pictures depicting pain sensory compared to emotional information. Furthermore, the facilitation of the NFR by pain pictures was positively correlated with the empathy trait of the observer. In contrast, the change in perceived shock-pain intensity was negatively correlated with empathic traits. This dissociation implies that low-level vicarious priming processes underlying pain facilitation may be downregulated at higher pain-processing stages in individuals reporting higher levels of empathy. We speculate that this process contributes to reducing self-other assimilation and is necessary to adopt higher-order empathic responses and altruistic behaviors.     

Effects of arterial and cardiopulmonary baroreceptor activation on the upper limb nociceptive flexion reflex and electrocutaneous pain in humans

Attenuation of the lower limb nociceptive flexion reflex (NFR) during the cardiac cycle has been attributed to inhibition of sensorimotor function by arterial baroreceptor activation. It has been proposed that cardiopulmonary baroreceptors might have similar inhibitory effects. This study examined the effects of arterial and cardiopulmonary baroreceptor stimulation on nociceptive responding in the upper limb by delivering electrocutaneous stimuli to the ulnar nerve at 0, 150, 300, 450, or 600 ms after the R-wave of the electrocardiogram while participants lay supine with their legs raised or lowered. Nociceptive responding varied in a quadratic manner with phase of the cardiac cycle; responses were lowest at R+450 ms. Nociceptive responding and pain ratings did not differ between postures suggesting no cardiopulmonary effects. This phasic modulation of the upper limb withdrawal response provides further support for arterial baroreceptor-mediated inhibition of nociceptive transmission.     

Nonpain goal pursuit inhibits attentional bias to pain

Although dealing with pain is a vital goal to pursue, most individuals are also engaged in the pursuit of other goals. The aim of the present experiment was to investigate whether attentional bias to pain signals is inhibited when one is pursuing a concurrent salient but nonpain task goal. Attentional bias to pain signals was measured in pain-free volunteers (n=63) using a spatial cueing task with pain cues and neutral cues. The pursuit of a concurrent goal was manipulated by including additional trials in which a digit appeared at the middle of the screen. Half of the participants (goal group) were instructed to name these additional stimuli aloud. In order to increase the affective-motivational value of this non-pain-related goal, monetary reward and punishment were made contingent upon the performance of this task. Participants of the control group did not perform the additional task. As predicted, the results show attentional bias to pain signals in the control group, but not in the goal group. This indicates that attentional bias to signals of impending pain is inhibited when one is engaged in the pursuit of another salient but nonpain goal. The results of this study underscore a motivational view on attention to pain, in which the pursuit of multiple goals, including nonpain goals, is taken into account.     

Induced fear reduces the effectiveness of a placebo intervention on pain

Fear was induced by the anticipation of electric shock in order to investigate whether fear reduced the effectiveness of a placebo intervention on reported pain and the acoustic startle reflex. Thirty-three subjects participated in a 3 Condition (Natural History [NH], Placebo [P], Placebo+Fear [PF])×3 Test (Pretest, Posttest 1, Posttest 2) within-subject design, tested on 3 separate days. Measures of fear were fear of pain (FOP), measured by the Fear of Pain Questionnaire (FPQ-III); fear-potentiated startle; and a self-report measure that assessed the effectiveness of the fear induction procedure. In the pain intensity data, there was a trend towards a placebo effect. This trend was abolished by induced fear, and was most pronounced in subjects who were highest in measures of fear. The placebo manipulation also caused a reduction in startle reflex amplitude. This effect was abolished by induced fear, and was strongest amongst high FOP subjects. In conclusion, induced fear abolished placebo analgesia, and this effect was strongest in subjects who had high scores on measures of fear.     

The persistence of pain behaviors in patients with chronic back pain is independent of pain and psychological factors

The primary purpose of the present study was to examine the temporal stability of communicative and protective pain behaviors in patients with chronic back pain. The study also examined whether the stability of pain behaviors could be accounted for by patients’ levels of pain severity, catastrophizing, or fear of movement. Patients (n = 70) were filmed on two separate occasions (i.e., baseline, follow-up) while performing a standardized lifting task designed to elicit pain behaviors. Consistent with previous studies, the results provided evidence for the stability of pain behaviors in patients with chronic pain. The analyses indicated that communicative and protective pain behavior scores did not change significantly from baseline to follow-up. In addition, significant test-retest correlations were found between baseline and follow-up pain behavior scores. The results of hierarchical multiple regression analyses further showed that pain behaviors remained stable over time even when accounting for patients’ levels of pain severity. Regression analyses also showed that pain behaviors remained stable when accounting for patients’ levels of catastrophizing and fear of movement. Discussion addresses the potential contribution of central neural mechanisms and social environmental reinforcement contingencies to the stability of pain behaviors. The discussion also addresses how treatment interventions specifically aimed at targeting pain behaviors might help to augment the overall impact of pain and disability management programs.     

Fear of injury and physical deconditioning in patients with chronic low back pain

OBJECTIVES: To test the assumption that fear of injury leads to disability and physical deconditioning in patients with chronic low back pain (CLBP) and to evaluate the relation between disability and physical deconditioning. DESIGN: Survey in a cross-sectional design. SETTING: A rehabilitation center in the Netherlands. PARTICIPANTS: Forty patients with nonspecific CLBP. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Fear of injury was measured with the Tampa Scale of Kinesiophobia. Physical fitness was expressed in aerobic fitness measured as predicted maximum oxygen consumption derived in a submaximal exercise test according the protocol of Siconolfi. Disability was measured with the Roland Disability Questionnaire. The association between fear of injury and physical fitness or disability was examined with correlational and multiple linear regression analyses. RESULTS: Fear of injury correlated significantly with disability (r=.44), but did not correlate significantly with aerobic fitness. There was no statistically significant association between disability and aerobic fitness. Multiple regression analysis revealed that aerobic fitness was predicted by gender only. CONCLUSIONS: Fear of injury appears to be more strongly associated with perceived disability than with aerobic fitness. The assumption that fear of injury leads to physical deconditioning was not confirmed in this sample of patients with CLBP.     

Fear of pain, not pain catastrophizing, predicts acute pain intensity, but neither factor predicts tolerance or blood pressure reactivity: an experimental investigation in pain-free individuals.

Previous studies of the Fear-Avoidance Model of Exaggerated Pain Perception have commonly included patients with chronic low back pain, making it difficult to determine which psychological factors led to the development of an "exaggerated pain perception". This study investigated the validity of the Fear-Avoidance Model of Exaggerated Pain Perception by considering the influence of fear of pain and pain catastrophizing on acute pain perception, after considering sex and anxiety. Thirty-two males and 34 females completed the State-Trait Anxiety Inventory, the Fear of Pain Questionnaire, and the Coping Strategies Questionnaire. Subjects underwent a cold pressor procedure and tolerance, pain intensity, and blood pressure reactivity were measured. Sex, anxiety, fear of pain, and pain catastrophizing were simultaneously entered into separate multiple regression models to predict different components of pain perception. Tolerance was not predicted by fear of pain, pain catastrophizing, or anxiety. Pain intensity at threshold and tolerance were significantly predicted by fear of pain, only. Blood pressure reactivity to pain was significantly predicted by anxiety, only. These results suggest that fear of pain may have a stronger influence on acute pain intensity when compared to pain catastrophizing, while neither of the factors predicted tolerance or blood pressure reactivity.     

The Effect of a Cartoon and an Information Video About Intravenous Insertion on Pain and Fear in Children Aged 6 to 12 Years in the Pediatric Emergency Unit: A Randomized Controlled Trial

IntroductionIntravenous insertion is the most common invasive procedure made for administering intravascular fluid and medicine. Peripheral venous catheterization may cause pain, fear, and stress in children. This study aimed to compare the effects of watching a cartoon and an information video about intravenous insertion on the pain and fear levels of children aged 6-12 years.MethodsThe study was an experimental, randomized controlled clinical trial. It was conducted with 477 children aged 6-12 years randomized into 3 groups: the informative animated video group, the cartoon group, and the control group. Fear and pain perception were evaluated on the basis of the feedback from the child, observer nurse, and parents. The Children’s Fear Scale was used to evaluate the fear level and the Wong-Baker FACES Scale was used to assess pain levels. Data were analyzed using one-way analysis of variance, the chi-square test, and the intraclass correlation coefficient test.ResultsThe children who watched the information video before the intravenous insertion procedure and those who watched a cartoon during the procedure had lower mean pain and fear scores as evaluated by the child (pain: F = 278.67, P = 0.001; fear: F = 294.88, P = 0.001), parent (pain: F = 279.53, P = 0.001; fear: F = 294.47, P = 0.001), and nurse (pain: F = 286.88, P = 0.001; fear: F = 300.81, P = 0.001) than children in the control group.DiscussionThis study showed that watching an animation video or a cartoon was effective in lowering children’s perceived level of pain and fear during an intravenous insertion intervention.     

Kinesiophobia is associated with pain intensity but not pain sensitivity before and after exercise: an explorative analysis

Objective

To compare clinical pain intensity, exercise performance, pain sensitivity and the effect of aerobic and isometric exercise on local and remote pressure pain thresholds (PPTs) in patients with chronic musculoskeletal pain with high and low levels of kinesiophobia.