Attentional Avoidance of Negative Experiences as Predictor of Postoperative Pain Ratings and Consumption of Analgesics: Comparison with Other Psychological Predictors

The effects of attentional and interpretation biases on later pain outcomes among younger and older adults: A prospective study

BACKGROUND

Studies examining the effect of biased cognitions on later pain outcomes have primarily focused on attentional biases, leaving the role of interpretation biases largely unexplored. Also, few studies have examined pain-related cognitive biases in elderly persons. The current study aims to fill these research gaps.

METHODS

Younger and older adults with and without chronic pain (N = 126) completed an interpretation bias task and a free-viewing task of injury and neutral scenes at baseline. Participants' pain intensity and disability were assessed at baseline and at a 6-month follow-up. A machine-learning data-driven approach to analysing eye movement data was adopted.

RESULTS

Eye movement analyses revealed two common attentional pattern subgroups for scene-viewing: an "explorative" group and a "focused" group. At baseline, participants with chronic pain endorsed more injury-/illness-related interpretations compared to pain-free controls, but they did not differ in eye movements on scene images. Older adults interpreted illness-related scenarios more negatively compared to younger adults, but there was also no difference in eye movements between age groups. Moreover, negative interpretation biases were associated with baseline but not follow-up pain disability, whereas a focused gaze tendency for injury scenes was associated with follow-up but not baseline pain disability. Additionally, there was an indirect effect of interpretation biases on pain disability 6 months later through attentional bias for pain-related images.

CONCLUSIONS

The present study provided evidence for pain status and age group differences in injury-/illness-related interpretation biases. Results also revealed distinct roles of interpretation and attentional biases in pain chronicity.

SIGNIFICANCE

Adults with chronic pain endorsed more injury-/illness-related interpretations than pain-free controls. Older adults endorsed more illness interpretations than younger adults. A more negative interpretation bias indirectly predicted pain disability 6 months later through hypervigilance towards pain.

Psycho-sensory relationships in chronic pain

BACKGROUND

Psychological variables contribute to pain- and injury-related outcomes. We examined the hypothesis that anatomical spread and intensity of persistent pain relate to anxiety-related variables: generalised anxiety, fear of pain and pain catastrophising.

METHODS

An online survey was used to gather data from 413 women with persistent pain (low back pain, n = 139; fibromyalgia syndrome, n = 95; neck pain, n = 55; whiplash, n = 41; rheumatoid arthritis, n = 37; migraine, n = 46). The spread and intensity of pain were assessed using the McGill pain chart and a Numerical Rating Scale. A Bayesian Structural Equation Model assessed if the intensity and spread of pain increased with anxiety-related variables. Men were also surveyed (n = 80), but the sample size was only sufficient for analysing if their data were consistent with the model for women.

RESULTS

Across subgroups of women, one standard deviation increase in catastrophising, generalised anxiety and fear corresponded to 27%, 7% and -1% additional pain areas and a 1.1, 0 and -0.1 change in pain intensity (on 0-10 scale), respectively. Overall, our clinical significance criterion - a 30% shift in pain variable in relation to one standard deviation increase in psychological variable - was not met. However, in subgroups it was met for pain spread (low back pain, neck pain and migraine) and pain intensity (migraine and neck pain) in relation to pain catastrophising. The model generally had low goodness-of-fit to men.

CONCLUSION

These data support a meaningful relationship between some anxiety-related variables and pain in women for some conditions. Since the model did not consistently fit the men, we may conclude that the relationships are moderated by sex. Clinician attention to psychological variables as potential contributing factors can be justified; however, research is needed to understand the relationship and whether psychological treatment can reduce pain.

Time course of attentional bias to painful facial expressions and the moderating role of attentional control: an eye-tracking study

Introduction

This study investigated the time course of attention to pain and examined the moderating effect of attentional control in the relationship between pain catastrophizing and attentional bias in chronic pain patients.

Methods

A total of 28 patients with chronic pain and 29 pain-free individuals observed pictures of pain, happy and neutral facial expressions while their gaze behaviour was recorded. Pain intensity and duration, anxiety, depression, stress, attentional control and pain catastrophizing were assessed by questionnaires.

Results

In all subjects, the pattern of attention for pain faces was characterized by initial vigilance, followed by avoidance. No significant difference was found between the two groups in terms of orientation towards the stimuli, the duration of first fixation, the average duration of fixation or number of fixations on the pain stimuli. Attentional control moderated the relationship between catastrophizing and overall dwell time for happy faces in pain patients, indicating that those with high attentional control and high catastrophizing focused more on happy faces, whereas the reverse was true for those with low attentional control.

Conclusion

This study supported the vigilance-avoidance pattern of attention to painful facial expressions and a moderation effect of attentional control in the association between pain catastrophizing and attentional bias to happy faces among pain patients.

Psychometric Properties of the German Version of the Pain Vigilance and Awareness Questionnaire (PVAQ) in Pain-Free Samples and Samples with Acute and Chronic Pain

Purpose

The way individuals attend to pain is known to have a considerable impact on the experience and chronification of pain. One method to assess the habitual “attention to pain” is the Pain Vigilance and Awareness Questionnaire (PVAQ). With the present study, we aimed to test the psychometric properties of the German version of the PVAQ across pain-free samples and across patients with acute and chronic pain.

Method

Two samples of pain-free individuals (student sample (N = 255)/non-student sample (N = 362)) and two clinical pain samples (acute pain patients (N = 105)/chronic pain patients (N = 36)) were included in this cross-sectional evaluation of the German PVAQ. Factor structure was assessed using exploratory and confirmatory factor analyses. Reliability was assessed using internal consistency (Cronbach’s alpha). Construct validity was tested by assessing correlations between PVAQ and theoretically related constructs.

Results

Exploratory factor analysis (non-student sample) and confirmatory factor analysis (student sample, acute pain patient sample) suggested that a two-factor solution best fitted our data (“attention to pain,” “attention to changes in pain”). Internal consistency ranged from acceptable to good in all four samples. As hypothesized, the PVAQ correlated significantly with theoretically related constructs in all four samples, suggesting good construct validity in pain-free individuals and in pain patients.

Conclusion

The German PVAQ shows good psychometric properties across samples of pain-free individuals and patients suffering from pain that are comparable to PVAQ versions of other languages. Thus, the German PVAQ seems to be a measure of pain vigilance equally valid as found in other countries.

Chronic Pain and Selective Attention to Pain Arousing Daily Activity Pictures: Evidence From an Eye Tracking Study

Introduction

According to the pain research literature, attentional bias for pain is the mechanism responsible for the development and maintenance of fear of pain in patients with chronic pain. However, there is still some debate about the exact mechanism and the role of faster engagement versus difficulty in disengagement in the development of attentional bias.

Methods

To investigate attentional bias in patients with chronic pain, we used an eye-tracker with the pictures of pain-provoking activities and compared the results with an age- and gender-matched group of pain-free participants. In addition, other measures of pain-related cognition and pain severity ratings were included to assess their contribution to the attentional bias toward pain-related information.

Results

Calculating the frequency of the first fixations showed that both groups fixated initially on pain-provoking pictures compared to neutral one. Calculating the speed of fixations showed that control participants were faster in fixating on neutral stimuli, but patients with pain were faster in fixating on pain-provoking pictures, indicating a relative vigilance for the pain-related stimuli among them. These patients reported that the intensity of pain in the previous week was positively correlated with the speed of their fixation on the painful stimuli.

Conclusion

Although these results did not provide unequivocal support for the vigilance-avoidance hypothesis, they are generally consistent with the results of studies using eye tracking technology. Furthermore, our findings put a question over characterization of attentional biases in patients with chronic pain by simply relating that to difficulty in disengaging from pain-related stimuli.

[Postoperative pain therapy in Germany. Status quo]

A great deal of progress has been made in the field of postoperative pain therapy in the last 20 years. Beginning from clinical trials on the effectiveness of individual procedures, such as epidural anesthesia and patient-controlled analgesia, a wide range of healthcare services research as well as basic research with human and animal experiments has been established. Whereas health services research in the 1980s and 1990s focused more on the implementation of acute pain services, outcome-oriented research approaches are nowadays the center of attention. Acute pain registries and pain certification projects initiated in Germany have to be mentioned particularly in this respect. Basic research papers from recent years increasingly address specific aspects of acute postoperative pain and have provided translational approaches that are applied around the world for studying neurobiological mechanisms of postoperative pain. At the same time, interdisciplinary cooperation in research projects has led to a better understanding of complex correlations regarding predictors and mechanisms (including psychosocial aspects) of acute and in recent times also chronic pain after surgery. In parallel, evidence-based medicine has found its way into acute pain medicine in Germany. In 2007, clinical acute pain therapy in Germany was enhanced by S3 level guidelines for the first time; however, the implementation is still incomplete. In future, questions concerning mechanism-based therapy of acute pain need to be equally in the center of attention of research, such as prevention of persisting pain after surgery and acute pain of different origins.

[Psychological prophylaxis training for coping with postoperative pain. Long-term effects]

INTRODUCTION

The present study was performed to investigate the effect of multidimensional psychological prophylaxis training focusing on coping with cognitive-emotional pain on recovery within the first 12 months after surgery. The training included the following three components: (1) education about pain, analgesia and psychological aspects of coping with pain, (2) training for coping with pain and (3) body-centered relaxation.

MATERIAL AND METHODS

In the study 48 young male patients (surgical correction of a chest malformation) were assessed 1 day before surgery, at discharge and 3, 6 and 12 months postoperatively concerning postoperative pain intensity and pain disability as well as pain anxiety, pain catastrophizing and pain hypervigilance. Additionally, 24 of these patients received training on cognitive-emotional coping with pain 1 day before surgery and 1-3 days after surgery (each session 1 h).

RESULTS

The proportion of patients with clinically relevant improvement was significantly higher in the training group compared to the control group. This was the case for acute pain intensity (approximately 1 week after surgery), pain disability 3 months later and pain anxiety 12 months after surgery.

CONCLUSION

The resurgence of pain anxiety after 12 months could only be found in the control group and could be due to the upcoming surgical removal of the transsternal metal implant. The prophylaxis training can therefore be seen as a protective factor for long-term management of surgery-related consequences and future pain experiences.

Pain in an era of armed conflicts: Prevention and treatment for warfighters and civilian casualties

Chronic pain is a common squealae of military- and terror-related injuries. While its pathophysiology has not yet been fully elucidated, it may be potentially related to premorbid neuropsychobiological status, as well as to the type of injury and to the neural alterations that it may evoke. Accordingly, optimized approaches for wounded individuals should integrate primary, secondary and tertiary prevention in the form of thorough evaluation of risk factors along with specific interventions to contravene and mitigate the ensuing chronicity. Thus, Premorbid Events phase may encompass assessments of psychological and neurobiological vulnerability factors in conjunction with fostering preparedness and resilience in both military and civilian populations at risk. Injuries per se phase calls for immediate treatment of acute pain in the field by pharmacological agents that spare and even enhance coping and adaptive capabilities. The key objective of the Post Injury Events is to prevent and/or reverse maladaptive peripheral- and central neural system's processes that mediate transformation of acute to chronic pain and to incorporate timely interventions for concomitant mental health problems including post-traumatic stress disorder and addiction We suggest that the proposed continuum of care may avert more disability and suffering than the currently employed less integrated strategies. While the requirements of the armed forces present a pressing need for this integrated continuum and a framework in which it can be most readily implemented, this approach may be also instrumental for the care of civilian casualties.

Reward devaluation: Dot-probe meta-analytic evidence of avoidance of positive information in depressed persons

Cognitive theories of depression and anxiety have traditionally emphasized the role of attentional biases in the processing of negative information. The dot-probe task has been widely used to study this phenomenon. Recent findings suggest that biased processing of positive information might also be an important aspect of developing psychopathological symptoms. However, despite some evidence suggesting persons with symptoms of depression and anxiety may avoid positive information, many dot-probe studies have produced null findings. The present review used conventional and novel meta-analytic methods to evaluate dot-probe attentional biases away from positive information and, for comparison, toward negative information, in depressed and anxious individuals. Results indicated that avoidance of positive information is a real effect exhibiting substantial evidential value among persons experiencing psychopathology, with individuals evidencing primary symptoms of depression clearly demonstrating this effect. Different theoretical explanations for these findings are evaluated, including those positing threat-processing structures, even-handedness, self-regulation, and reward devaluation, with the novel theory of reward devaluation emphasized and expanded. These novel findings and theory suggest that avoidance of prospective reward helps to explain the cause and sustainability of depressed states. Suggestions for future research and methodological advances are discussed.

Association of genetic and psychological factors with persistent pain after cosmetic thoracic surgery

The genetic control of pain has been repeatedly demonstrated in human association studies. In the present study, we assessed the relative contribution of 16 single nucleotide polymorphisms in pain-related genes, such as cathechol-O-methyl transferase gene (COMT), fatty acid amino hydrolase gene (FAAH), transient receptor potential cation channel, subfamily V, member 1 gene (TRPV1), and δ-opioid receptor gene (OPRD1), for postsurgical pain chronification. Ninety preoperatively pain-free male patients were assigned to good or poor outcome groups according to their intensity or disability score assessed at 1 week, 3 months, 6 months, and 1 year after funnel chest correction. The genetic effects were compared with those of two psychological predictors, the attentional bias toward positive words (dot-probe task) and the self-reported pain vigilance (Pain Vigilance and Awareness Questionnaire [PVAQ]), which were already shown to be the best predictors for pain intensity and disability at 6 months after surgery in the same sample, respectively. Cox regression analyses revealed no significant effects of any of the genetic predictors up to the end point of survival time at 1 year after surgery. Adding the genetics to the prediction by the attentional bias to positive words for pain intensity and the PVAQ for pain disability, again no significant additional explanation could be gained by the genetic predictors. In contrast, the preoperative PVAQ score was also, in the present enlarged sample, a meaningful predictor for lasting pain disability after surgery. Effect size measures suggested some genetic variables, for example, the polymorphism rs1800587G>A in the interleukin 1 alpha gene (IL1A) and the COMT haplotype rs4646312T>C/rs165722T>C/rs6269A>G/rs4633T>C/rs4818C>G/rs4680A>G, as possible relevant modulators of long-term postsurgical pain outcome. A comparison between pathophysiologically different predictor groups appears to be helpful in identifying clinically relevant predictors of chronic pain.

A more pessimistic life orientation is associated with experimental inducibility of a neuropathy-like pain pattern in healthy individuals

The clinical pattern of neuropathic pain, diagnosed using the quantitative sensory testing (QST) battery (German Research Network on Neuropathic Pain), could be partly mimicked in healthy volunteers after topical capsaicin application. However, similar to clinical neuropathic pain that develops in only a subgroup of patients who have a neurologic lesion, this attempt to mimick a neuropathic pain pattern succeeded only in a small fraction (18%) of healthy individuals. In the present assessment, we pursued the hypothesis that the inducible subgroup differed from the other healthy participants with respect to their psychological phenotype. Therefore, in an observational study, participants were assessed using a comprehensive set of psychological variables comprising general psychological and pain-related cognitive-emotional mechanisms. The sum scores of the questionnaires were significantly linearly correlated with each other. Principal component analysis indicated that a major source of variance (46%) could be attributed to dispositional optimism examined via the Life Orientation Test (LOT). The LOT score significantly differed between the groups of participants, either those in whom a neuropathy-like pattern of pain assessed via QST could be partly (50-60% of the 11 QST parameters) induced (n = 20) or not (n = 90; P = .0375). It emerged again as the main selection criterion in a classification and regression tree predicting a participant's group assignment (inducible neuropathy-like QST pattern versus noninducible neuropathy-like QST pattern) at a cross-validated accuracy of 95.5 ± 2.1%. Thus, the few participants in a random sample of healthy volunteers who, after topical capsaicin application, partly resemble (to a degree of about 60%) the clinical pattern of neuropathic pain in the QST test battery, are preselectable on the basis of psychological factors, with a particular emphasis on pessimistic life attitudes.

PERSPECTIVE

In a small fraction of 18% of healthy volunteers, topical capsaicin application resulted in a neuropathy-like pattern in 50 to 60% of the components of a clinical test battery. These individuals displayed a more pessimistic life attitude as assessed by means of the LOT.

The relationship among psychological factors, neglect-like symptoms and postoperative pain after total knee arthroplasty

Neglect-like symptoms have been defined as a loss of perception of a limb, with pain and excessive effort necessary to move the limb. This phenomenon has been studied in patients with complex regional pain syndrome, but has not been assessed in patients who have undergone orthopedic procedures such as total knee arthroplasty. The authors of this study assessed neglect-like symptoms in a group of 90 patients three and six weeks after total knee arthroplasty.

BACKGROUND:

Persistent postoperative pain has a significant relationship with patient health and satisfaction.

OBJECTIVES:

To investigate the prevalence and association of neglect-like symptoms (NLS) and other psychological factors on postoperative pain in patients following total knee arthroplasty (TKA). NLS are defined as the loss of perception of the limb with pain and excessive effort required to move the limb. The authors hypothesized that NLS were an important contributor to postoperative pain.

METHODS:

The factors influencing pain were investigated using a longitudinal study with assessments at three and six weeks postsurgery. The relationships among demographic factors (age, body weight, body mass index), psychological factors (State-Trait Anxiety Inventory and Pain Catastrophizing Scale [PCS]) and NLS with postoperative pain were investigated in 90 patients after TKA. The associations among motor functions (muscle strength of knee extension, range of motion), sensory functions (joint position sense and two-point discrimination in the thigh) and NLS were also investigated.

RESULTS:

At three and six weeks after surgery, 36% and 19% of patients, respectively, experienced NLS. In hierarchical multiple regression analysis, NLS and PCS scores were significantly associated with postoperative pain, while joint position sense and range of motion were significantly associated with NLS.

CONCLUSIONS:

These results suggest that facilitation of sensory integration is important in rehabilitation after TKA because NLS appears to result from impaired sensory integration. The association of PCS scores with postoperative pain and NLS suggests the need to provide appropriate postoperative education to reduce persistent negative thoughts regarding future pain.

Effects of spray and stretch on postneedling soreness and sensitivity after dry needling of a latent myofascial trigger point

OBJECTIVES

To investigate (1) the effect of spray and stretch versus control on reducing postneedling soreness of 1 latent myofascial trigger point (MTrP) and (2) whether higher levels of psychological distress are associated with increased postneedling pain intensity.

DESIGN

A 72-hour follow-up, single-blind randomized controlled trial.

SETTING

University community.

PARTICIPANTS

Healthy volunteers (N=70; 40 men, 30 women) aged 18 to 36 years (mean age, 21±4y) with latent MTrP in 1 upper trapezius muscle.

INTERVENTION

All subjects received a dry needling application over the upper trapezius muscle. Then, participants were randomly divided into 2 groups: an intervention group, which received spray and stretch over the needled trapezius muscle, and a control group, which did not receive any intervention.

MAIN OUTCOME MEASURES

Visual analog scale (at postneedling, posttreatment, and 6, 12, 24, 48, and 72h after needling), pressure pain threshold (at preneedling, postneedling, and 24 and 48h after needling). Psychological distress was evaluated by using the Symptom Checklist-90-Revised.

RESULTS

Repeated-measures analysis of variance demonstrated a significant interaction between group and time (F3,204.8=3.19; P<.05; ηp(2)=.04) for changes in postneedling soreness. Between-group differences were significant only immediately after intervention (P=.002), and there were no differences found between groups after 6 hours of the intervention (P>.05). Repeated measures of covariance showed that none of the psychological covariates affected these results. Somatization, anxiety, interpersonal sensitivity, and hostility were significantly correlated (P<.05) with postneedling pain intensity. Repeated-measures analysis of variance did not show a significant effect of spray and stretch on mechanical hyperalgesia (F2.6,175=1.9; P=.131; ηp(2)=.02).

CONCLUSIONS

The spray and stretch had a short-term (<6h) effect in reducing postneedling soreness of a latent MTrP. Pressure pain threshold did not significantly change after spray and stretch. Psychological factors are related to postneedling pain.

Persistent postsurgical pain: evidence from breast cancer surgery, groin hernia repair, and lung cancer surgery

The prevalences of severe persistent postsurgical pain (PPP) following breast cancer surgery (BCS), groin hernia repair (GHR), and lung cancer surgery (LCS) are 13, 2, and 4-12 %, respectively. Estimates indicate that 80,000 patients each year in the U.S.A. are affected by severe pain and debilitating impairment in the aftermath of BCS, GHR, and LCS. Data across the three surgical procedures indicate a 35-65 % decrease in prevalence of PPP at 4-6 years follow-up. However, this is outweighed by late-onset PPP, which appears following a pain-free interval. The consequences of PPP include severe impairments of physical, psychological, and socioeconomic aspects of life. The pathophysiology underlying PPP consists of a continuing inflammatory response, a neuropathic component, and/or a late reinstatement of postsurgical inflammatory pain. While the sensory profiles of PPP-patients and pain-free controls are comparable with hypofunction on the surgical side, this seems to be accentuated in PPP-patients. In BCS-patients and GHR-patients, the sensory profiles indicate inflammatory and neuropathic components with contribution of central sensitization. A number of surgical factors including increased duration of surgery, repeat surgery, more invasive surgical techniques, and intraoperative nerve lesion have been associated with PPP. One of the most consistent predictive factors for PPP is high intensity acute postsurgical pain, but also psychological factors including anxiety, catastrophizing trait, depression, and psychological vulnerability have been identified as significant predictors of PPP. The quest to identify improved surgical and anesthesiological techniques to prevent severe pain and functional impairment in patients after surgery continues.

Does severe acute pain provoke lasting changes in attentional and emotional mechanisms of pain-related processing? A longitudinal study

Pain experiences, learning, and genetic factors have been proposed to shape attentional and emotional processes related to pain. We aimed at investigating whether a singular major pain experience also changes cognitive-emotional processing. The influence of acute postoperative pain after cosmetic surgery of the thorax was tested in 80 preoperatively pain-free male individuals. Acute pain was measured as independent variable during the first week postsurgery by pain intensity ratings and the requested analgesic boluses (Patient-Controlled Epidural Analgesia (PCEA)). Pain catastrophizing (Pain Catastrophizing Scale (PCS)), pain anxiety (Pain Anxiety and Symptom Scale (PASS)), pain hypervigilance (Pain Vigilance and Awareness Questionnaire (PVAQ)), and attentional biases to emotionally loaded stimuli (including pain) in a dot-probe task were assessed 1 week, 3 months, and 6 months postsurgery as dependent variables. Hierarchical regression analyses were performed to test whether the 2 acute pain parameters can predict these cognitive-emotional variables. As a rigorous test, significant prediction was required in addition to the prediction of the dependent variables by themselves with lag-1. Acute pain (mainly the pain ratings) appeared to be a significant predictor for PCS, PASS, and PVAQ 1 week after surgery (deltaR(2) = [8.7% to 11.3%]). In contrast, the attentional biases in the dot-probe task could not be predicted by the pain ratings. The levels of pain catastrophizing and pain hypervigilance increased in the acute phase after surgery when influenced by acute pain and declined, along with pain anxiety, during the next 3 months. In conclusion, a one-time intense pain experience, such as acute postoperative pain, appeared to produce at least short-lived changes in the attentional and emotional processing of pain.

A single-nucleotide polymorphism in SCN9A may decrease postoperative pain sensitivity in the general population

BACKGROUND

This study aimed to explore the role of a nonsynonymous single-nucleotide polymorphism, 3312G>T, in SCN9A, which was identified in probands with congenital indifference to pain, but which is also present in normal controls, in the prediction of individual baseline pain perception, and postoperative pain sensitivity in the general population.

METHODS

Preoperative pressure pain thresholds and tolerance were measured in 200 patients undergoing pancreatectomy, and the postoperative pain sensitivity and analgesic demand were recorded. These variables were compared according to the SCN9A 3312G>T alleles. Logistic regression analysis was used to test the role of preoperative variables in the prediction of postoperative inadequate analgesia.

RESULTS

The 3312Tallele was present in 22 individuals, and the 3312Tallele frequency was 5.5% (22/200). The average patient-controlled analgesia pressing frequency and opioid consumption in 3312G patients was significantly higher than those in 3312T patients (2.70 [SD: 0.84] vs. 2.05 [SD: 0.43], P < 0.001; 100.8 [SD: 40.7] vs. 74.8 [SD: 20.8] ml, P = 0.006). The incidence of inadequate analgesia in 3312G patients was significantly higher than that of patients carrying the 3312Tallele (29.2% vs. 4.5%; P = 0.013). Carrying the 3312Tallele and having a higher pressure pain threshold predicted a lower risk of postoperative inadequate analgesia, with an odds ratio of 0.10 (95% CI: 0.01 to 0.76, P = 0.026) and 0.32 (95% CI: 0.13 to 0.82, P = 0.018), respectively.

CONCLUSION

Patients carrying the SCN9A 3312Tallele presented with lower postoperative pain sensitivity in the presence of a similar surgical pain stimulus, and had a lower likelihood of developing inadequate analgesia than those carrying the 3312Gallele.

Surgically induced neuropathic pain: understanding the perioperative process

Nerve damage takes place during surgery. As a consequence, significant numbers (10%-40%) of patients experience chronic neuropathic pain termed surgically induced neuropathic pain (SNPP). The initiating surgery and nerve damage set off a cascade of events that includes both pain and an inflammatory response, resulting in "peripheral and central sensitization," with the latter resulting from repeated barrages of neural activity from nociceptors. In affected patients, these initial events produce chemical, structural, and functional changes in the peripheral and central nervous systems (CNS). The maladaptive changes in damaged nerves lead to peripheral manifestations of the neuropathic state-allodynia, sensory loss, shooting pains, etc, that can manifest long after the effects of the surgical injury have resolved. The CNS manifestations that occur are termed "centralization of pain" and affect sensory, emotional, and other (eg, cognitive) systems as well as contributing to some of the manifestations of the chronic pain syndrome (eg, depression). Currently there are no objective measures of nociception and pain in the perioperative period. As such, intermittent or continuous pain may take place during and after surgery. New technologies including direct measures of specific brain function of nociception and new insights into preoperative evaluation of patients including genetic predisposition, appear to provide initial opportunities for decreasing the burden of SNPP, until treatments with high efficacy and low adverse effects that either prevent or treat pain are discovered.

Predictors of postoperative movement and resting pain following total knee replacement

This study determined preoperative predictors of movement and resting pain following total knee replacement (TKR). We hypothesized that younger patients with higher preoperative pain intensity, pain sensitivity, trait anxiety, pain catastrophizing, and depression would be more likely to experience higher postoperative movement pain than older patients with lower scores on these variables prior to surgery, and that predictors would be similar for resting pain. Demographics, analgesic intake, anxiety, depression, pain catastrophizing, resting pain, movement pain (ie, during active knee range of motion), and quantitative sensory tests were performed preoperatively on 215 participants scheduled for a unilateral TKR. On postoperative day 2, analgesic intake, resting pain, and movement pain were again assessed. Significant predictors of moderate or severe movement pain were higher preoperative movement pain, von Frey pain intensity, and heat pain threshold. People with severe movement pain preoperatively were 20 times more likely to have severe movement pain postoperatively. When the influence of preoperative movement pain was removed, depression became a predictor. Significant predictors of moderate to severe resting pain were higher preoperative resting pain, depression, and younger age. These results suggest that patients with higher preoperative pain and depression are more likely to have higher pain following TKR, and younger patients may have higher resting pain. Cutaneous pain sensitivity predicted movement pain but not resting pain, suggesting that mechanisms underlying movement pain are different from resting pain. Aggressive management of preoperative pain, pain sensitivity, and depression prior to surgery may facilitate postoperative recovery.

Global catastrophizing vs catastrophizing subdomains: assessment and associations with patient functioning

OBJECTIVE

The primary objectives of the current study were to 1) confirm the three-factor model of the Pain Catastrophizing Scale (PCS) items in a Japanese sample and 2) identify the catastrophizing subdomain(s) most closely associated with measures of pain and functioning in a sample of individuals with chronic pain.

DESIGN

This was based on a cross-sectional observational study.

SETTING

This study was conducted in a university-based clinic.

PATIENTS

One hundred and sixty outpatients with chronic pain participated in this study.

OUTCOME MEASURES

Patients completed the PCS, the Brief Pain Inventory, and the Hospital Anxiety and Depression Scale; 30 patients completed the PCS again between 1 and 4 weeks later.

RESULTS

Confirmatory factor analysis supported a three-factor structure of the Japanese version of the PCS, and univariate and multivariate associations with validity criterion supported the validity of the measure. Catastrophic helplessness was shown to make a unique contribution to the prediction of pain intensity, pain interference and depression, and catastrophic magnification made a unique contribution to the prediction of anxiety.

CONCLUSIONS

The findings support the cross-cultural generalizability of the three-factor structure of the PCS and indicate that the PCS-assessed catastrophizing subdomains provide greater explanatory power than the PCS total score for understanding pain-related functioning.