Hypervigilance as Predictor of Postoperative Acute Pain: Its Predictive Potency Compared With Experimental Pain Sensitivity, Cortisol Reactivity, and Affective State

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.

Measuring mechanical pain: the refinement and standardization of pressure pain threshold measurements

Pain thresholds are widely used in behavioral research, but unlike other pain modalities, a standardized assessment of pressure pain remains a challenge. In this research, we describe the application of an automatic pressure algometer with a linear increase in force. Ergonomically designed fixation devices were developed to increase the accuracy and to shorten the time of each measurement. Ten healthy volunteers were included in a pilot study to test the algometry method. Pressure pain thresholds (PPTs) were investigated over 2 experimental days in three nonconsecutive runs at 29 measurement sites. During the experiment, subjects reported their subjective sleepiness, level of state-anxiety, psychological status and the perceived pain intensity of each measurement. Pain intensity ratings indicate that instructions were followed. State-anxiety and subjective sleepiness levels were low throughout the experiment. The method has proven to be suitable for standardized PPT measurements across the body in an ergonomic, safe, and user-friendly fashion.

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.

Enhanced short-term sensitization of facial compared with limb heat pain

Habituation and sensitization are important features of individual sensitivity to repetitive noxious stimulation and have been investigated in numerous studies. However, it is unclear whether these phenomena vary depending on the site of stimulation. Here we compared short-term and long-term effects of painful heat stimulation on the forehead and limb using an established longitudinal heat pain paradigm performed over 8 consecutive days in 36 healthy volunteers. Participants were randomized into 2 groups; participants received repetitive heat pain stimulation either on the left volar forearm or on the left side of the forehead. Our data show a comparable degree of habituation over the course of 8 days in both groups. However, participants in the trigeminal stimulation group exhibited stronger within-session sensitization (indexed by a higher within-session increase in pain intensity ratings) than those who received the forearm stimulation. Furthermore, over the course of the experiment we found a correlation between habituation and anxiety, showing less habituation in participants with higher trait anxiety scores. Our findings are in line with somatotopic differences in response to painful stimulation and a higher proneness of trigeminal pain to sensitization processes, which might be explained by the biological relevance of the head and facial area for vital functions. The contribution of this sensitivity to the development and maintenance of clinical facial pain and headache disorders warrants further investigation.

PERSPECTIVE

This study uses psychophysical methods to evaluate the differences in long-term habituation and short-term sensitization to heat pain between the trigeminal and spinal systems. We found stronger sensitization for trigeminal compared with nociceptive stimuli on the forearm. The contribution of this sensitivity to clinical pain states warrants further investigation.

Phasic and tonic pain differentially impact the interruptive function of pain

The interruptive effect of painful experimental stimulation on cognitive processes is a well-known phenomenon. This study investigated the influence of pain duration on the negative effects of pain on cognition. Thirty-four healthy volunteers performed a rapid serial visual presentation task (RSVP) in which subjects had to detect (visual detection task) and count the occurrence of a target letter (working memory task) in two separate sessions while being stimulated on the left volar forearm with either short (2 sec) or long (18 sec) painful heat stimuli of equal subjective intensity. The results show that subjects performed significantly worse in the long pain session as indexed by decreased detection and counting performance. Interestingly, this effect on performance was also observed during control trials of the long pain session in which participants did not receive any painful stimulation. Moreover, subjects expected long painful stimulation to have a greater impact on their performance and individual expectation correlated with working memory performance. These findings suggest that not only the length of painful stimulation but also its expected ability to impair cognitive functioning might influence the interruptive function of pain. The exact relevance of expectation for the detrimental effects of pain on cognitive processes needs to be explored in more detail in future studies.

Pain after knee arthroplasty: an unresolved issue

PURPOSE

Despite the recent advances in the understanding of pain mechanisms and the introduction of new drugs and new techniques in the postoperative management, pain after total knee arthroplasty (TKA) is still an unresolved issue. It affects the quality of life and rehabilitation of an important percentage of patients undergoing TKA. The aim of this narrative review was to give an overview on pain mechanisms and multimodal pain management.

METHODS

A review of all peer-reviewed articles on pain after knee arthroplasty was performed by two reviewers. Recent articles on incisional pain mechanisms were included because of their importance in the understanding of postsurgical pain. Search was performed in Pubmed, Cochrane and Google Scholar data bases.

RESULTS

Postsurgical pain mechanisms are based on both local and systemic inflammatory reactions. Peri-operative pain management starts with the anaesthetic technique and resides on a multimodal analgesia regimen. New concepts, drugs and techniques have shown their efficacy in reducing the severity of acute postoperative pain and the risk of developing chronic pain after TKA.

CONCLUSION

This narrative review offers a clear overview of pain mechanism after knee arthroplasty and an understanding on how multimodal pain management can reduce the intensity and duration of pain after knee arthroplasty.

Management of a patient with chronic low back pain and multiple health conditions using a pain mechanisms-based classification approach

STUDY DESIGN

Case report.

BACKGROUND

Pain can lead to a significant reduction in quality of life. A pain mechanisms-based classification scheme has been outlined to improve management of patients with pain, but studies describing its use are limited. Evidence for physical therapy interventions in those with chronic pain and multiple health conditions is also lacking. This case report describes management of a patient with chronic pain and multiple health conditions.

CASE DESCRIPTION

A 29-year-old man presented with a 3-year history of low back pain and 11-month history of lower extremity paresthesia. Current health conditions included left-sided hemiparesis secondary to a stroke, pancreatic kidney transplant, left-sided blindness, and osteoporosis secondary to hyperparathyroidism. Inability to walk to school and sit through class, and pain-related sleep disruption were the primary activity and participation restrictions. Outcome measures included the numeric pain rating scale, global rating of change, Oswestry Disability Index, and pain medication usage. A score of 12 on the Leeds assessment of neuropathic symptoms and signs (LANSS) pain scale indicated the presence of neuropathic pain, but other pain mechanisms were also hypothesized to be present. Treatment was designed to improve patient goals considering these pain mechanisms.

OUTCOMES

The patient was seen for 20 visits over 6 months. Ten months after the initial evaluation, the patient's Oswestry Disability Index scores improved by more than 50% and the patient achieved all initially stated goals without pain medication.

DISCUSSION

A pain mechanisms-based approach assisted in the management of a patient with chronic pain and multiple health conditions. Using this approach may enhance clinical decision making when managing individuals with chronic pain.

LEVEL OF EVIDENCE

Therapy, level 4.

Conditioned pain modulation and situational pain catastrophizing as preoperative predictors of pain following chest wall surgery: a prospective observational cohort study

BACKGROUND

Variability in patients' postoperative pain experience and response to treatment challenges effective pain management. Variability in pain reflects individual differences in inhibitory pain modulation and psychological sensitivity, which in turn may be clinically relevant for the disposition to acquire pain. The aim of this study was to investigate the effects of conditioned pain modulation and situational pain catastrophizing on postoperative pain and pain persistency.

METHODS

Preoperatively, 42 healthy males undergoing funnel chest surgery completed the Spielberger's State-Trait Anxiety Inventory and Beck's Depression Inventory before undergoing a sequential conditioned pain modulation paradigm. Subsequently, the Pain Catastrophizing Scale was introduced and patients were instructed to reference the conditioning pain while answering. Ratings of movement-evoked pain and consumption of morphine equivalents were obtained during postoperative days 2-5. Pain was reevaluated at six months postoperatively.

RESULTS

Patients reporting persistent pain at six months follow-up (n = 15) were not significantly different from pain-free patients (n = 16) concerning preoperative conditioned pain modulation response (Z = 1.0, P = 0.3) or level of catastrophizing (Z = 0.4, P = 1.0). In the acute postoperative phase, situational pain catastrophizing predicted movement-evoked pain, independently of anxiety and depression (β = 1.0, P = 0.007) whereas conditioned pain modulation predicted morphine consumption (β = -0.005, P = 0.001).

CONCLUSIONS

Preoperative conditioned pain modulation and situational pain catastrophizing were not associated with the development of persistent postoperative pain following funnel chest repair. Secondary outcome analyses indicated that conditioned pain modulation predicted morphine consumption and situational pain catastrophizing predicted movement-evoked pain intensity in the acute postoperative phase. These findings may have important implications for developing strategies to treat or prevent acute postoperative pain in selected patients. Pain may be predicted and the malfunctioning pain inhibition mechanism as tested with CPM may be treated with suitable drugs augmenting descending inhibition.

Pre-operative pain sensitivity: A prediction of post-operative outcome in the obstetric population

CONTEXT

Experimental assessments can determine pain threshold and tolerance, which mirror sensitivity to pain. This, in turn, influences the post-operative experience.

AIMS

The study intended to evaluate whether the pre-operative pressure and electrical pain tests can predict pain and opioid requirement following cesarean delivery.

SETTINGS AND DESIGN

Research was conducted on females scheduled for cesarean section at a tertiary care hospital of the state. Twenty women were enrolled, after obtaining written informed consent.

MATERIALS AND METHODS

PAIN ASSESSMENT WAS PERFORMED ON THE EVE OF CESAREAN SECTIONS USING THREE DEVICES: PainMatcher(;) determined electrical pain threshold while the algometers PainTest(™) FPN100 (manual) and PainTest(™) FPX 25 (digital) evaluated pressure pain threshold and tolerance. Post-operative pain relief included intravenous morphine administered by patient-controlled analgesia, diclofenac (100 mg, every 12 h, rectally, enforced) and paracetamol (1000 mg, every 4-6 h, orally, on patient request). Pain scores were reported on numerical rating scales at specified time intervals.

STATISTICAL ANALYSIS USED

Correlational and regression statistics were computed using IBM SPSS Statistics 21 software (IBM Corporation, USA).

RESULTS

A SIGNIFICANT CORRELATION WAS OBSERVED BETWEEN MORPHINE REQUIREMENT AND: (1) electrical pain threshold (r = -0.45, P = 0.025), (2) pressure pain threshold (r = -0.41 P = 0.036) and (3) pressure pain tolerance (r = -0.44, P = 0.026) measured by the digital algometer. The parsimonious regression model for morphine requirement consisted of electrical pain threshold (r(2)= 0.20, P = 0.049). The dose of morphine consumed within 48 h of surgery decreases by 0.9 mg for every unit increment in electrical pain threshold.

CONCLUSIONS

The predictive power of pain sensitivity assessments, particularly electrical pain threshold, may portend post-cesarean outcomes, including opioid requirements.

The association of personality, appraisal, catastrophising and vigilance with gastrointestinal symptom-specific anxiety

This study investigates the relationship between psychosocial factors and functional gastrointestinal disorder symptomatology by testing a more comprehensive and integrated model than found in prior research. A total of 233 respondents completed an online battery to assess factors such as personality, dysfunctional cognitions and gastrointestinal anxiety. Results based on path modelling provided support for the majority of the hypothesised pathways. This study implicates a number of personality factors and dysfunctional cognitive processes as relevant to functional gastrointestinal disorder symptom burden. These findings have implications for future research, including which dysfunctional cognitive processes should be targeted therapeutically.

Neural underpinnings of behavioural strategies that prioritize either cognitive task performance or pain

We previously discovered that when faced with a challenging cognitive task in the context of pain, some people prioritize task performance, while in others, pain results in poorer performance. These behaviours, designated respectively as A- and P-types (for attention dominates vs pain dominates), may reflect pain coping strategies, resilience or vulnerabilities to develop chronic pain, or predict the efficacy of treatments such as cognitive behavioural therapy. Here, we used a cognitive interference task and pain stimulation in 80 subjects to interrogate psychophysical, psychological, brain structure and function that distinguish these behavioural strategies. During concurrent pain, the A group exhibited faster task reaction times (RTs) compared to nonpain trials, whereas the P group had slower RTs during pain compared to nonpain trials, with the A group being 143 ms faster than the P group. Brain imaging revealed structural and functional brain features that characterized these behavioural strategies. Compared to the performance-oriented A group, the P group had (1) more gray matter in regions implicated in pain and salience (anterior insula, anterior midcingulate cortex, supplementary motor area, orbitofrontal cortex, thalamus, caudate), (2) greater functional connectivity in sensorimotor and salience resting-state networks, (3) less white matter integrity in the internal and external capsule, anterior thalamic radiation and corticospinal tract, but (4) were indistinguishable based on sex, pain sensitivity, neuroticism, and pain catastrophizing. These data may represent neural underpinnings of how task performance vs pain is prioritized and provide a framework for developing personalized pain therapy approaches that are based on behaviour-structure-function organization.

Predicting acute pain after cesarean delivery using three simple questions

BACKGROUND

Interindividual variability in postoperative pain presents a clinical challenge. Preoperative quantitative sensory testing is useful but time consuming in predicting postoperative pain intensity. The current study was conducted to develop and validate a predictive model of acute postcesarean pain using a simple three-item preoperative questionnaire.

METHODS

A total of 200 women scheduled for elective cesarean delivery under subarachnoid anesthesia were enrolled (192 subjects analyzed). Patients were asked to rate the intensity of loudness of audio tones, their level of anxiety and anticipated pain, and analgesic need from surgery. Postoperatively, patients reported the intensity of evoked pain. Regression analysis was performed to generate a predictive model for pain from these measures. A validation cohort of 151 women was enrolled to test the reliability of the model (131 subjects analyzed).

RESULTS

Responses from each of the three preoperative questions correlated moderately with 24-h evoked pain intensity (r = 0.24-0.33, P < 0.001). Audio tone rating added uniquely, but minimally, to the model and was not included in the predictive model. The multiple regression analysis yielded a statistically significant model (R = 0.20, P < 0.001), whereas the validation cohort showed reliably a very similar regression line (R = 0.18). In predicting the upper 20th percentile of evoked pain scores, the optimal cut point was 46.9 (z =0.24) such that sensitivity of 0.68 and specificity of 0.67 were as balanced as possible.

CONCLUSIONS

This simple three-item questionnaire is useful to help predict postcesarean evoked pain intensity, and could be applied to further research and clinical application to tailor analgesic therapy to those who need it most.

Does vigilance to pain make individuals experts in facial recognition of pain?

BACKGROUND

It is well known that individual factors are important in the facial recognition of pain. However, it is unclear whether vigilance to pain as a pain-related attentional mechanism is among these relevant factors.

OBJECTIVES

Vigilance to pain may have two different effects on the recognition of facial pain expressions: pain-vigilant individuals may detect pain faces better but overinclude other facial displays, misinterpreting them as expressing pain; or they may be true experts in discriminating between pain and other facial expressions. The present study aimed to test these two hypotheses. Furthermore, pain vigilance was assumed to be a distinct predictor, the impact of which on recognition cannot be completely replaced by related concepts such as pain catastrophizing and fear of pain.

METHODS

Photographs of neutral, happy, angry and pain facial expressions were presented to 40 healthy participants, who were asked to classify them into the appropriate emotion categories and provide a confidence rating for each classification. Additionally, potential predictors of the discrimination performance for pain and anger faces - pain vigilance, pain-related catastrophizing, fear of pain--were assessed using self-report questionnaires.

RESULTS

Pain-vigilant participants classified pain faces more accurately and did not misclassify anger as pain faces more frequently. However, vigilance to pain was not related to the confidence of recognition ratings. Pain catastrophizing and fear of pain did not account for the recognition performance.

CONCLUSIONS

Moderate pain vigilance, as assessed in the present study, appears to be associated with appropriate detection of pain-related cues and not necessarily with the overinclusion of other negative cues.

Pain-specific modulation of hippocampal activity and functional connectivity during visual encoding

Acute and chronic pain automatically attract attention and thus interfere with cognitive functioning. Impaired memory is a prominent complaint of patients with chronic pain that substantially contributes to pain-related disability. In this fMRI study, we investigated the specific influence of pain on neural processes of memory encoding in healthy human volunteers using a visual task. To investigate the specificity of the interruptive effect of pain on the encoding of visual objects, objects were presented (1) alone, (2) with painful heat stimuli, or (3) with auditory stimuli that were matched for unpleasantness to the heat stimuli. The interruptive effect of concomitant aversive stimulation on behavioral measures and neural processing was assessed in a categorization task during encoding and in a subsequent recognition task. Pain interfered with object processing and encoding of visual stimuli. On the behavioral level, this resulted in slower reaction times during the categorization task for pain compared with auditory stimuli and in a lower recognition rate in the pain condition but not in the tone condition. Pain catastrophizing amplified this interruptive effect of pain. On the neural level, this pain-related disruption of encoding was associated with reduced activity in the right anterior hippocampus during encoding. Moreover, the hippocampus exhibited reduced functional connectivity with extrastriate regions during painful stimulation relative to auditory stimulation. In summary, our results show a pain-related disruption of visual encoding over and above the unpleasantness of a stimulus, suggesting a pain-specific interruptive mechanism that interferes with an early stage of memory formation.

Thermal detection and pain thresholds but not pressure pain thresholds are correlated with psychological factors in women with chronic whiplash-associated pain

Whiplash-associated disorders (WAD) have been associated with sensory disturbances such as hypersensitivity or hypoesthesia. Different psychological factors seem to be important for prognosis and symptom presentation in WAD. Multivariate correlations between pain thresholds for pressure (PPT), cold and heat (CPT, HPT), detection thresholds for cold and warmth, pain intensity variables, and psychological aspects in women with chronic WAD (n=28) and in healthy pain-free controls (n=29) were investigated. Quantitative Sensory Testing (QST) for thermal thresholds and algometry for PPT at various sites in the body were used. Psychological aspects, including catastrophizing, anxiety, and depression were registered using a questionnaire. WAD showed generalized decreased PPT and CPT, altered HPT and cold detection thresholds in the upper part of the body, and a worse psychological situation. Multivariate correlations were found between QST and PPT variables, habitual pain, and psychological factors in WAD. Different psychological variables were generally stronger predictors of CPT and HPT than pain intensity in WAD. Pain intensity aspects were generally the strongest predictors of PPT in WAD. In contrast, no correlations existed between QST and PPT variables and psychological variables in controls. These results indicate the need to consider that a blend of factors influences the pain thresholds in chronic WAD and emphasize the need for a biopsychosocial model when interpreting QST and PPT variables.

Factor structure and psychometric properties of the Chinese version of the 20-item Pain Anxiety Symptoms Scale (ChPASS-20)

CONTEXT

The Pain Anxiety Symptoms Scale (PASS) was designed to assess pain-related anxiety and fear. Although the scale is a reliable measure with good psychometric properties, its validity among ethnic Chinese has yet to be evaluated.

OBJECTIVES

This study aimed to translate the English-language version of the 20-item PASS into Chinese (ChPASS-20) and evaluate its factor structure, reliability, and validity.

METHODS

A total of 223 Chinese patients with chronic musculoskeletal pain attending orthopedic specialist clinics completed the ChPASS-20, the Chronic Pain Grade questionnaire, the Chinese version of the 11-item Tampa Scale of Kinesiophobia, the Hospital Anxiety and Depression Scale, and questions assessing sociodemographic and pain characteristics.

RESULTS

Confirmatory factor analyses showed that all the five-factor solutions tested met the minimum acceptable fit criterion. The four ChPASS-20 subscales and the entire scale demonstrated good internal consistency (Cronbach's αs: 0.72-0.92). All ChPASS-20 scales showed significant positive correlations with depression, pain intensity, and disability. Hierarchical multiple regression analyses showed that the ChPASS-20 total score predicted concurrent depression [F(4,159)=11.97, P<0.001], pain intensity [F(4,161)=2.47, P<0.05], and pain disability [F(4,191)=5.47, P<0.001] scores, and the ChPASS-20 Avoidance subscale (standardized beta coefficient=0.21, P<0.05) emerged as a significant independent predictor of concurrent pain disability.

CONCLUSION

Our data support the factorial validity, reliability, and construct validity of the ChPASS-20 in a Chinese population.

Prediction of Experimental Pain Sensitivity by Attention to Pain-Related Stimuli in Healthy Individuals

The aim of the present study was to assess the predictive power of the processing of pain-related information, comprising concepts of hypervigilance to pain, pain catastrophizing, and pain-related anxiety (questionnaires) as well as attentional processes related to pain-related stimuli (dot-probe task) in explaining individual differences in experimental pain sensitivity (pressure/thermal pain threshold). In 160 healthy participants (ages 13–61; 80 females), results of hierarchical multiple regression analyses showed that self-reported hypervigilance contributed significantly to the prediction of pain sensitivity, whereas pain catastrophizing and anxiety did not. However, inconsistent with prediction, the effect was in the opposite direction, indicating that vigilance to pain sensations or stimuli is associated with lower pain sensitivity in healthy individuals. Entering the attentional bias indices from the dot-probe task showed that an increased bias to pain words is related to higher experimental pain sensitivity, which confirms the hypothesis.

[Predictors of chronic pain following surgery. What do we know?]

Chronic postoperative pain is known to be a significant clinical and economic problem. The estimated mean incidence is high and varies between 10 and 50%, with variations mostly related to procedure-specific conditions. High-risk types of surgeries are e.g. thoracotomy, breast or inguinal hernia surgery and amputations. Although there is increasing knowledge about the incidence of chronic postoperative pain after certain types of surgical procedures, there are only limited data related to the mechanisms and pathophysiology leading to chronic pain after surgery. Neuropathic pain components have been discussed, especially following operations with a high incidence of nerve damage (for example axillary lymphadenectomy). Besides surgical factors it seems that there are a number of other factors which likely increase the risk of chronic postoperative pain. These predictors for the development of chronic postoperative pain are multiple and include individual genetic factors, age and sex of the individual patient, preoperative chronic pain, psychosocial factors, neurophysiological factors, intraoperative nerve and muscle damage, postoperative complications and acute pain in the early postoperative period. Quantitative sensory testing including tests of inhibitory circuits like DNIC might help to predict the risk of individual patients even before surgery has started. The perioperative identification of patients who are at high risk for developing chronic pain after surgery is therefore a major goal for the future. This may help to develop preventive treatment strategies and avoid treatments with side effects for patients who are not at risk for developing chronic pain after surgery. Due to a lack of appropriate data for sufficient preventive approaches an effective postoperative acute pain management and a nerve-conserving surgical technique are the major keys in the prophylaxis of chronic postoperative pain.

Attentional and emotional mechanisms of pain processing and their related factors: a structural equations approach

BACKGROUND/OBJECTIVE

It is known that maladaptive attentional and emotional mechanisms of pain processing - as indicated by constructs such as pain hypervigilance, pain-related anxiety and pain catastrophizing - play an important role in the development and maintenance of chronic pain conditions. However, little is known to date about the potential risk factors for these forms of maladaptive processing. The aim of the present study was to shed more light on this issue. A very comprehensive set of predictor variables was examined in healthy pain-free subjects.

METHOD

Participants were 92 young and healthy subjects (mean [+/- SD] age 26.99+/-6.90 years; 47 men, 45 women). Maladaptive attentional and emotional mechanisms of pain processing were assessed by self-report measures of pain hypervigilance, pain-related anxiety and pain catastrophizing, as well as by a dot-probe task. The comprehensive set of predictor variables included measures of affective and bodily distress (depression, anxiety and somatization), experimental pain sensitivity, and cortisol reactivity. Directed relationships were estimated by using structural equation modelling.

RESULTS

Structural equation modelling revealed a significant path from affective and bodily distress to self-reported maladaptive attentional and emotional pain processing. In contrast, the paths from pain sensitivity and cortisol reactivity did not reach the level of significance.

CONCLUSION

These results support the position that anxiety and depression, as well as somatization, contribute to the aberrance of attentional and emotional mechanisms of pain processing. Surprisingly, the assumption of a close relationship between these maladaptive mechanisms of pain processing and pain sensitivity could not be confirmed.