Does gender affect appraisal of pain and pain coping strategies?

OBJECTIVE: To investigate the impact of gender and a set of pain characteristics on the threat or challenge appraisal of pain and the impact of these appraisals on the coping strategies used to manage the pain. DESIGN: This study used a community telephone survey to examine these relationships for a troublesome pain experienced by respondents in the 2 weeks preceding the interview. STUDY RESPONDENTS: The sampling frame consisted of 1,430 households randomly selected from the Halifax-Dartmouth-Bedford community. Of the 390 respondents with a troublesome pain in the 2 weeks preceding the interview, 309 respondents agreed to participate (79% response rate). RESULTS: Women tended to report more pain located in the head and more somatic problems. They reported significantly more intense pain. For women and men, the most important impact on threat appraisal of pain was overall interference of pain and emotional upset due to pain. These two variables accounted for 48% of the variance in threat appraisal for women and 37% of the variance for men. There was no gender difference in emotional upset due to pain or in the impact of emotional upset on threat appraisal. There was no gender difference in challenge appraisal. Threat appraisal was associated with increased catastrophizing whereas challenge appraisal was associated with positive self-statements. Women reported significantly more problem solving, social support, positive self-statements, and palliative behaviors than did men. CONCLUSIONS: Interference of pain has a greater impact on threat appraisal of pain for women. Increasing threat appraisal is associated with health care utilization for women, but women's more frequent use of several coping strategies is unrelated to their appraisal of pain. Appraisal of pain may have important implications on coping and overall well-being of women and men.     

Self-reports of pain intensity and direct observations of pain behavior: when are they correlated?

Meta-analytic techniques were utilized to investigate the relationship between self-reports of pain intensity and direct observations of pain behavior. Estimation of the overall effect size from 29 studies and 85 effect sizes yielded a moderately positive association, z=0.26. High variability across studies permitted a random-effects moderator analysis that determined chronicity of pain, the timing of the pain assessment, the use of global measures of pain behavior, and pain site significantly moderate the relationship between self-reports of pain intensity and direct observations of pain behavior. These findings indicate that self-reports of pain intensity and direct observations of pain behavior are more likely to be significantly related to each other when the individual being studied has acute pain (z=0.35), when the self-report of pain intensity data are collected soon after the observation of pain behavior (z=0.40), when global composite measures are used to quantify pain behavior (z=0.37), and when the person being observed suffers from chronic low back pain (z=0.30). Other factors not found to be significant moderators include: extent of observer training, relevance of the pain-inducing task, and pain behavior observation measure used. The implications of the findings for the assessment of pain are discussed.     

The role of associative learning and fear in the development of chronic pain – a comparison of chronic pain and post-traumatic stress disorder

Background:

Associative learning is the theory that two stimuli can be paired to produce similar behavioral responses. In this model, a previously innocuous stimulus can become paired with a noxious stimulus to a point that this previously innocuous stimulus can result in the perception of pain.

Objectives:

This review discusses concepts related to neural activation and structural alterations in the presence of both chronic pain and post-traumatic stress disorder (PTSD). The role of associative learning and protective memory-based behavioral responses in the perception of pain is explored to provide a framework to inform clinical management of individuals with chronic pain and will be linked to the presence of actual or perceived threat or fear.

Major Findings:

Current research demonstrates that in individuals with chronic pain, cortical and subcortical processing of information shifts from normal nocioceptive processing areas to the medial prefrontal, anterior cingulate, and insular cortices, as well as the hippocampus (Hip) regions, all of which also show dysregulation, signs of gray matter atrophy, and changes in epigenetic coding. Because these regions are involved in memory, emotional processing, learning, and conditioning, it is reasonable to suggest that associative learning may be involved in the processing of both pain and PTSD.

Conclusions:

Clinically, rehabilitation paradigms that incorporate early intervention, positive expectation, therapeutic neuroscience education, visual imagery, movement retraining, and manual therapy all have the potential to change not only pain behavior but also the neural circuitry, epigenetic coding, and cortical morphology underlying chronic pain.     

Does failure hurt? The effects of failure feedback on pain report,pain tolerance and pain avoidance

In this study an experiment was conducted to examine whether failure experiences have an effect on pain report, pain tolerance and pain avoidance. Furthermore, it was investigated if negative affectivity (NA) affected the impact of failure feedback on pain report, either as a mediator, in the case of negative state affect, or as a moderator when NA as a personality trait was considered. Fifty-four healthy female volunteers were included and randomly assigned to one of three conditions: (1) failure feedback; (2) success feedback; (3) neutral control task. After the manipulation, subjects were given a cold pressor task in order to obtain pain measures. Regarding the effects of failure feedback on pain report, it was found that, in comparison with success feedback, failure feedback led to increased pain report. With regard to pain tolerance, pain was tolerated for longer when preceded by success feedback than when preceded by failure feedback. Differences between failure and control conditions did not reach significance. With regard to pain avoidance, no differences between the conditions were found. The hypothesized mediating role of negative state affect was not found. Though in the hypothesized direction, no significant effect was found for NA-trait moderating the influence of failure on pain. The discussion focuses on a number of research questions that remain to be answered, and the clinical relevance of the effects of failure and success experiences on pain report and pain tolerance.     

How a clock can change your pain? The illusion of duration and pain perception

The intensity of experimental pain is known to be dependent on stimulation duration. However, it remains unknown whether this effect arises largely from the actual stimulus duration or is substantially influenced by the subject’s perception of the stimulus duration. In the present study, we questioned this issue by misleading the perception of the duration of pain in a population of 36 healthy volunteers stimulated with a thermode. To this aim, time was signified by a clock with rotating hands in which imperceptible differences in speed rotation had been introduced. Subjects were therefore immersed in 2 comparative conditions in which time was manipulated to provide the illusion of either long or short duration of the painful stimulus. In a first condition (“full-length” clock), participants were instructed that pain would last for a complete revolution of the clock’s hands, whereas in the second condition (“shortened” clock), revolution was reduced by 25%. Although the intensity and the real duration of stimulation were identical in both conditions, the intensity of pain was significantly reduced when the perception of time was misleadingly shortened by the manipulated clock. This study suggests that the perceived duration of a noxious stimulation may influence the perceived intensity of pain.     

Mechanisms-based classifications of musculoskeletal pain: part 3 of 3: symptoms and signs of nociceptive pain in patients with low back (± leg) pain

As a mechanisms-based classification of pain 'nociceptive pain' (NP) refers to pain attributable to the activation of the peripheral receptive terminals of primary afferent neurones in response to noxious chemical, mechanical or thermal stimuli. The symptoms and signs associated with clinical classifications of NP have not been extensively studied. The purpose of this study was to identify symptoms and signs associated with a clinical classification of NP in patients with low back (± leg) pain. Using a cross-sectional, between-subjects design; four hundred and sixty-four patients with low back (± leg) pain were assessed using a standardised assessment protocol after which their pain was assigned a mechanisms-based classification based on experienced clinical judgement. Clinicians then completed a clinical criteria checklist indicating the presence/absence of various symptoms and signs. A regression analysis identified a cluster of seven clinical criteria predictive of NP, including: 'Pain localised to the area of injury/dysfunction', 'Clear, proportionate mechanical/anatomical nature to aggravating and easing factors', 'Usually intermittent and sharp with movement/mechanical provocation; may be a more constant dull ache or throb at rest', and the absence of 'Pain in association with other dysesthesias', 'Night pain/disturbed sleep', 'Antalgic postures/movement patterns' and 'Pain variously described as burning, shooting, sharp or electric-shock-like'. This cluster was found to have high levels of classification accuracy (sensitivity 90.9%, 95% CI: 86.6-94.1; specificity 91.0%, 95% CI: 86.1-94.6). Pattern recognition of this empirically-derived cluster of symptoms and signs may help clinicians identify an assumed dominance of NP mechanisms in patients with low back pain disorders.     

Onecase of herb rehabilitation for knee joints swelling and pain

Background：Mostmiddle－agedandagedpatientswithkneejointsswellingandpain（kneejointsdegenerationisshownbyXray）areobese，thekneejointsarechronicallydamagedbyheavyloadandmuchwalkorextraexercises．AccordingtotheChinesemedicinetheories：themiddle－agedandtheagedhaveweakliverandkidney，theirsinewsandbonesarenotwellnourished，whendamagedbytoomuchlabor，theyareattackedbywindandmoistanditisthemaincauseofthedisease．Objective：TodiscussthetreatingeffectsofChineseherbonkneejointsswellingandpain．Unit…     

Ratings of pain and activity limitation on the visual analogue scale and global impression of change in multimodal rehabilitation of back pain – analyses at group and individual level

Purpose: To evaluate changes in pain intensity and activity limitation, at group and individual levels, and their associations with the global impression of change after multimodal rehabilitation in patients with back pain.

Method: Patients with long-term back pain (n?=?282) participated in a 4-week programme with a follow-up after 6 months. Visual analogue scales (VAS) were used to rate pain intensity and activity limitation. Global impression of change (GIC) was rated on a 7-category scale. The sign test, the Svensson method and the Spearman rank correlation were used for analyses.

Results: Significantly lower ratings in pain and activity limitation at follow-up were found at group level. However, a large individual variability was found by the Svensson method. The correlations between GIC and changes in pain and activity limitation were r_s??=_? 0.49 and r_s =?_?0.50, respectively. A rated GIC of at least “much better” on group level showed changes of ≥20?mm on the VAS.

Conclusions: At group level, lower VAS ratings were found in patients with back pain. However, a large individual variability in pain and activity limitation was also found resulting in low to moderate associations between GIC and the change in VAS ratings. The large individual variability might be due to the impreciseness in the ratings on the VAS. We have presented a critical discussion of statistical methods in connection with the VAS.

• Implications for Rehabilitation

• The use of VAS as a rating instrument may be questioned, especially for perceived pain intensity which is a too complex experience to be rated on a line without any visible categories.

• Single ratings of pain intensity should preferably be complemented with the ratings of activity limitation in patients with long-term back pain.

• Global impression of change is a suggested inclusive rating after rehabilitation.

• The improvement desired by the patient should preferably be determined before rehabilitation.

     

Mechanisms-based classifications of musculoskeletal pain: part 2 of 3: symptoms and signs of peripheral neuropathic pain in patients with low back (± leg) pain

As a mechanisms-based classification of pain 'peripheral neuropathic pain' (PNP) refers to pain arising from a primary lesion or dysfunction in the peripheral nervous system. Symptoms and signs associated with an assumed dominance of PNP in patients attending for physiotherapy have not been extensively studied. The purpose of this study was to identify symptoms and signs associated with a clinical classification of PNP in patients with low back (± leg) pain. Using a cross-sectional, between-subjects design; four hundred and sixty-four patients with low back (± leg) pain were assessed using a standardised assessment protocol. Patients' pain was assigned a mechanisms-based classification based on experienced clinical judgement. Clinicians then completed a clinical criteria checklist specifying the presence or absence of various clinical criteria. A binary logistic regression analysis with Bayesian model averaging identified a cluster of two symptoms and one sign predictive of PNP, including: 'Pain referred in a dermatomal or cutaneous distribution', 'History of nerve injury, pathology or mechanical compromise' and 'Pain/symptom provocation with mechanical/movement tests (e.g. Active/Passive, Neurodynamic) that move/load/compress neural tissue'. This cluster was found to have high levels of classification accuracy (sensitivity 86.3%, 95% CI: 78.0-92.3; specificity 96.0%, 95% CI: 93.4-97.8; diagnostic odds ratio 150.9, 95% CI: 69.4-328.1). Pattern recognition of this empirically-derived cluster of symptoms and signs may help clinicians identify an assumed dominance of PNP mechanisms in patients with low back pain disorders in a way that might usefully inform subsequent patient management.     

Does aerobic exercise improve pain perception and mood? A review of the evidence related to healthy and chronic pain subjects

Aerobic exercise can cause an acute improvement in mood as well as a reduction in the perception of pain from a painful stimulus. Regular exercise training also may offer some protection from depression, is clinically useful in treating certain psychiatric and chronic pain conditions, and may allow for an enhancement of the acute improvements in mood from a single exercise session. The utility of aerobic exercise training for improving mood disturbances and pain perception among patients with chronic pain requires further investigation.     

Contribution of PKMζ-dependent and independent amplification to components of experimental neuropathic pain

Injuries can induce adaptations in pain processing that result in amplification of signaling. One mechanism may be analogous to long-term potentiation and involve the atypical protein kinase C, PKMζ. The possible contribution of PKMζ-dependent and independent amplification mechanisms to experimental neuropathic pain was explored in rats with spinal nerve ligation (SNL) injury. SNL increased p-PKMζ in the rostral anterior cingulate cortex (rACC), a site that mediates, in part, the unpleasant aspects of pain. Inhibition of PKMζ within the rACC by a single administration of ζ-pseudosubstrate inhibitory peptide (ZIP) reversed SNL-induced aversiveness within 24 hours, whereas N-methyl-d-aspartate receptor blockade with MK-801 had no effects. The SNL-induced aversive state (reflecting "spontaneous" pain), was re-established in a time-dependent manner, with full recovery observed 7 days post-ZIP administration. Neither rACC ZIP nor MK-801 altered evoked responses. In contrast, spinal ZIP or MK-801, but not scrambled peptide, transiently reversed evoked hypersensitivity, but had no effect on nerve injury-induced spontaneous pain. PKMζ phosphorylation was not altered by SNL in the spinal dorsal horn. These data suggest that amplification mechanisms contribute to different aspects of neuropathic pain at different levels of the neuraxis. Thus, PKMζ-dependent amplification contributes to nerve injury-induced aversiveness within the rACC. Moreover, unlike mechanisms maintaining memory, the consequences of PKMζ inhibition within the rACC are not permanent in neuropathic pain, possibly reflecting the re-establishment of amplification mechanisms by ongoing activity of injured nerves. In the spinal cord, however, both PKMζ-dependent and independent mechanisms contribute to amplification of evoked responses, but apparently not spontaneous pain.     

Documentation of pain assessment and treatment: How are we doing?

The purpose of this analysis was to evaluate documentation of practice provided by a multidisciplinary team of nurses, physicians, and pharmacists who participated in an educational program on postoperative pain management. Chart audit of 787 patient charts at 6 sites revealed documentation of pain histories in approximately 75% of the charts, most often in the surgeon's history and physical examination. Examination of multiple assessment items indicated that the experimental group, relative to the control group, experienced an increase of more than 10% in the documentation of pain intensity, pain quality, pain duration, numeric rating scale used, pain behavior, factors that increase pain, vital signs, sedation level, cognitive status, social interaction, and mood from before the program to 6 months after the program. Across all sites, documentation of assessment, treatment, and treatment outcome data was infrequent and inconsistent. Calculation of documentation of 4 items that constituted a focused assessment of postoperative pain on the surgical floor revealed a significant program effect for assessment of pain quality and pain intensity. A postprogram survey of participants in the educational program revealed an increase in discussion of postoperative pain management with other practitioners and an increase in use of a 0 to 10 scale to rate pain. More documentation of patient pain history, clinical problems, treatment, and follow-up action is needed to improve practice and research.     

Transgenic studies of pain and analgesia: mutation or background genotype?

The application of transgenic (knockout) technology to the study of pain is rapidly expanding. Despite its power, this technique has several shortcomings that complicate the interpretation of the data obtained. Although compensation by other genes is a well recognized problem, issues related to the background genotype of the mutant mice are less well appreciated. This review describes these confounds as they apply to studies of pain and pain inhibition. We show that the 129 and C57BL/6 mouse strains, which provide the default genetic background on which null mutants are constructed, display significant and sometimes extreme phenotypic differences in many assays of nociception, hypersensitivity, and analgesia. Although problems related to the differential responsiveness of the two strains are minimized by placing knockouts onto "pure" 129 and/or C57BL/6 backgrounds, we also illustrate that neither of these strains are particularly representative of inbred mice in general. Procedures to reduce confounds and converging evidence must be used to accurately determine the functions of the targeted genes in pain-related phenomena.