Perceived Pain Intensity Research Articles

Merely Possessing a Placebo Analgesic Reduced Pain Intensity: Preliminary Findings from a Randomized Design

An experiment was conducted to examine whether the mere possession of a placebo analgesic cream would affect perceived pain intensity in a laboratory pain-perception test. Healthy participants read a medical explanation of pain aimed at inducing a desire to seek pain relief and then were informed that a placebo cream was an effective analgesic drug. Half of the participants were randomly assigned to receive the cream as an unexpected gift, whereas the other half did not receive the cream. Subsequently, all participants performed the cold-pressor task. We found that participants who received the cream but did not use it reported lower levels of pain intensity during the cold-pressor task than those who did not receive the cream. Our findings constitute initial evidence that simply possessing a placebo analgesic can reduce pain intensity. The study represents the first attempt to investigate the role of mere possession in understanding placebo analgesia. Possible mechanisms and future directions are discussed.

Greater fear of visceral pain contributes to differences between visceral and somatic pain in healthy women.

This functional magnetic resonance imaging study addressed similarities and differences in behavioral and neural responses to experimental visceral compared with somatic pain stimuli and explored the contribution of fear of pain to differences between pain modalities. In N = 22 healthy women, we assessed blood oxygen level-dependent responses to rectal distensions and cutaneous heat stimuli matched for perceived pain intensity. Fear of pain and pain unpleasantness were assessed before and after scanning. Visceral pain was more fear evoking and more unpleasant, and trial-by-trial intensity ratings failed to habituate across trials (all interactions modality × time: P < 0.01). Differences in fear of pain and pain intensity independently contributed to greater visceral pain unpleasantness (combined regression model: R(2) = 0.59). We observed joint neural activations in somatosensory cortex and frontoparietal attention network (conjunction analysis: all pFWE <0.05), but distensions induced greater activation in somatosensory cortex, dorsal and ventral anterior insula, dorsal anterior and midcingulate cortices, and brainstem, whereas cutaneous heat pain led to enhanced activation in posterior insula and hippocampus (all pFWE <0.05). Fear of visceral pain correlated with prefrontal activation, but did not consistently contribute to neural differences between modalities. These findings in healthy women support marked differences between phasic pain induced by rectal distensions vs cutaneous heat, likely reflecting the higher salience of visceral pain. More studies with clinically relevant pain models are needed to discern the role of fear in normal interindividual differences in the response to different types of pain and as a putative risk factor in the transition from acute to chronic pain.

Responses to Slowly Repeated Evoked Pain Stimuli in Fibromyalgia Patients: Evidence of Enhanced Pain Sensitization.

The pathophysiology of fibromyalgia has been related to central pain sensitization. This study tested a laboratory protocol evaluating responses to slowly repeated evoked pain stimuli (SREP) that may index central pain sensitization in fibromyalgia. A between-subjects controlled laboratory study. Twenty-four fibromyalgia patients and 24 healthy participants. A SREP protocol was administered to all subjects, consisting of a single series of nine low-intensity pressure stimuli of five-second duration and thirty-second interstimulus interval. Subjective evoked pain intensity was assessed with a visual analogical scale. Clinical fibromyalgia pain was assessed with the McGill Pain Questionnaire. Perceived pain intensity increased during the SREP protocol in fibromyalgia patients but not in healthy participants. Neither pain threshold nor pain tolerance was associated with SREP. Degree of SREP sensitization was associated with McGill Pain Questionnaire-Sensory ratings of fibromyalgia pain. The effect size for differences between the fibromyalgia and healthy control groups was greater, and the overlaps of the groups distributions lower, for SREP sensitization than for traditional evoked pain measures of pain threshold and tolerance. SREP demonstrated higher specificity in discriminating fibromyalgia and control groups relative to pain threshold or tolerance. A protocol employing a single series of nine low-suprathreshold-intensity slowly repeated pain stimuli elicits increased perceived pain in fibromyalgia patients, consistent with central sensitization despite relatively long interstimulus intervals. SREP appears to be more useful than traditional evoked pain threshold tolerance measures in terms of predicting levels of clinical pain and discriminating between fibromyalgia patients and healthy individuals.

A longitudinal exploration of pain tolerance and participation in contact sports

Background/aimsAthletes who choose to engage in contact sports do so with the knowledge that participation will bring pain in the form of contact with others, injury, and from exertion. Whilst athletes who play contact sports have been shown to have higher pain tolerance than those who do not, it is unclear whether this is a result of habituation over time, or as a result of individual differences at the outset. The aim was to compare pain responses over an athletic season in athletes who participated in contact sport and those who disengaged from it. MethodsOne hundred and two new contact athletes completed measures of cold and ischaemic pain tolerance, perceived pain intensity, pain bothersomeness, pain coping styles and attendance at the start, middle (4 months) and end (8 months) of their season. The athletes were drawn from martial arts, rugby and American football. Cluster analysis placed 47 athletes into a participating category and 55 into a non-participating cluster. ResultsParticipating athletes had higher ischaemic pain tolerance at the start (r=0.27, p=0.05), middle (r=0.41, p<0.0001) and end of the season (r=0.57, p<0.0001) compared to non-participating athletes. In addition participating athletes were more tolerant to cold pain at the end of the season (r=0.39, p<0.0001), compared to non-participating athletes. Participating athletes also exhibited higher direct coping, catastrophized less about injury pain and also found contact pain to be less bothersome physically and psychologically compared to non-participating athletes. Participating athletes were more tolerant of ischaemic pain at the end of the season compared to the start (r=0.28, p=0.04). Conversely non-participating athletes became significantly less tolerant to both pain stimuli by the end of the season (cold pressor; r=0.54, p<0.0001; ischaemia; r=0.43, p=0.006). Pain intensity as measured by a visual analogue scale did not change over the season for both groups. ConclusionsThose who cease participation in contact sports become less pain tolerant of experimental pain, possibly a result of catastrophizing. The results suggest that athletes who commit to contact sports find pain less bothersome over time, possibly as a result of experience and learning to cope with pain. Athletes who continue to participate in contact sports have a higher pain tolerance, report less bothersomeness and have higher direct coping than those who drop out. In addition, tolerance to ischaemic pain increased over the season for participating athletes. ImplicationsHaving a low pain tolerance should not prevent athletes from taking part in contact sports, as pain becomes less bothersome in athletes who adhere to such activities. Participating in contact sports may result in maintained cold pain tolerance, increased ischaemic pain tolerance, reduced catastrophizing and better coping skills. Coaches can therefore work with athletes to develop pain coping strategies to aid adherence to contact sports.

Unique Contributions of Acceptance and Catastrophizing on Chronic Pain Adaptation.

Pain catastrophizing and acceptance represent distinct but interrelated constructs that influence adaptation to chronic pain. Clinical and laboratory research suggest that higher levels of catastrophizing and lower levels of acceptance predict worse functioning; however, findings have been mixed regarding which specific outcomes are associated with each construct. The current study evaluates these constructs in relation to pain, affect, and functioning in a treatment-seeking clinical sample. Participants included 249 adult patients who were admitted to an interdisciplinary chronic pain rehabilitation program and completed measures of pain and related psychological and physical functioning. Hierarchical multiple regression analyses indicated that pain catastrophizing and acceptance both significantly, but differentially, predicted depressive symptoms and pain-related negative affect. Only pain catastrophizing was a unique predictor of perceived pain severity, whereas acceptance uniquely predicted pain interference and performance in everyday living activities. There were no significant interactions between acceptance and catastrophizing, suggesting no moderation effects. Findings from the current study indicate a pattern of results similar to prior studies in which greater levels of catastrophic thinking is associated with higher perceived pain intensity whereas greater levels of acceptance relate to better functioning in activities despite chronic pain. However, in the current study, both acceptance and catastrophizing were associated with negative affect. These relationships were significant beyond the effects of clinical and demographic variables. These results support the role of pain acceptance as an important contribution to chronic pain-related outcomes alongside the well-established role of pain catastrophizing. Results are limited by reliance on self-report data, cross-sectional design, and low racial/ethnic diversity.

Association between pain extent and health status in whiplash associated disorders

Background. Whiplash associated disorders (WAD) are a complex phenomenon associated with relevant social and economic burdens. Many people with chronic WAD show widespread pain which can be observed from the patient’s pain drawing. No studies have evaluated the relation of pain extent to perceived pain and disability, financial status, general health and psychological status in individuals with chronic WAD. Purpose. To evaluate the relation of pain extent to a number of variables related to the patients’ perceived pain and disability, their financial status, general health and psychological status. Methods. A total of 205 individuals with chronic WAD grade 2 or 3 were selected. The main outcome measure was pain extent, extracted from the pain drawing. Pain extent was evaluated in relation to sex, age, educational level, insurance status and financial status. Multiple linear regression analysis was then used to verify whether pain extent was significantly associated with the other health indicators including perceived pain intensity and disability, health-related quality of life, pain catastrophizing, anxiety, depression and self-efficacy. Results: Pain extent was influenced by the sex of the participant (p<0.01) with larger pain extent in women compared to men (7.88±7.66 vs 5.40±6.44). People with unsettled insurance claims (p<0.05) and those with a worse financial situation (p<0.01) showed larger pain extent. Multiple linear regression models revealed that, when accounting for age, sex, education, insurance status, financial status and neck pain intensity, pain extent remained associated with perceived disability (p<0.01), depression (p<0.05), and self-efficacy (p<0.001). Conclusion: Women with chronic WAD, those with unsettled insurance claims and those with poorer financial status reported more widespread pain. When controlling for these factors, larger pain areas remained associated with perceived pain and disability, depression and self-efficacy. Implications: Pain drawings support the clinical evaluation of people with chronic WAD.

Retrospective analysis of self-reporting pain scores and pain management during head and neck IMRT radiotherapy: A single institution experience

AimsHead and neck carcinomas are relatively rare in the United Kingdom with an estimated 9000 cases diagnosed annually. However, pain associated with disease and treatment side effects such as oral mucositis present a major issue for therapy radiographers in providing effective care and maintaining radiotherapy treatment compliance, all factors that can compromise patient outcome if not managed appropriately. MethodThis retrospective analysis of self-reporting pain scores collected during a course of radiotherapy aims to assess the perceived pain intensity scores in 30 patients. Data was collected during radiographer review sessions held weekly to determine if any variables to perceived pain scores occurred during a course of radiotherapy. ResultsAs treatment progressed, the self-reporting pain scores within the cohort increased, in week one the total cohort pain score was 35, this increased to 114 in week 3 and in the final week had totalled 151. An escalation in pain was observed in week 3 of treatment possibly as a result of radiation induced inflammation alongside cytotoxic chemotherapy. ConclusionsThe findings of this study provide further evidence to an individualised approach to patient pain relief and providing regular on treatment reviews, thus maintaining patient comfort and ensuring continued treatment compliance.

P044 The effect of transcutaneous vagal nerve stimulation on experimental heat pain – A crossover blinded sham- and placebo-controlled investigation

Question Transcutaneous vagal nerve stimulation (TVNS) is a promising treatment for acute and chronic pain ( Busch et al., 2013 ), however the testing of TVNS within the experimental pain models yielded controversial results ( Busch et al., 2013 , Laqua et al., 2013 ). The aim was to investigate the effect of TVNS on perception of repetitive heat pain stimuli (RHPS) in comparison with sham and placebo procedure in healthy volunteers. Methods Forty-nine participants (25 females) underwent 4 RHPS sessions within an interval of 48 h in-between. During each session, 90 heat stimuli of individual pain tolerance temperature (ramp rate 20 °C/s, pulse duration 0.8 s, frequency of stimulation 0.33 Hz) were applied to the forearm using a CHEPS thermode (Medoc, Israel). The first (baseline) session was performed without intervention, during three following sessions either TVNS, sham (earlobe stimulation) or placebo condition were applied in a random crossover manner. Participants rated the perceived pain intensity of the first and each 10th stimulus using numeric rating scale 0–100. Data was analysed using ANOVA and Bonferroni adjusted multiple comparisons. Results Participants reported less pain during all interventional methods compared to baseline (p Download : Download high-res image (274KB) Download : Download full-size image ), whereas pain under TVNS was lower than under placebo procedure after 30 stimuli (p = 0.038, Fig. 1). The effect of TVNS and sham stimulation on RHPS perception was comparable. Conclusion We could confirm the hypoalgesic effects of TVNS, but these effects were not distinguishable from sham intervention in our study. However, we cannot exclude stimulation of cranial nerves during the placebo and sham condition because of possible acupressure effects and widespread neural activation after electrical stimulation of the earlobes.

Orbitofrontal cortex mediates pain inhibition by monetary reward.

Pleasurable stimuli, including reward, inhibit pain, but the level of the neuraxis at which they do so and the cerebral processes involved are unknown. Here, we characterized a brain circuitry mediating pain inhibition by reward. Twenty-four healthy participants underwent functional magnetic resonance imaging while playing a wheel of fortune game with simultaneous thermal pain stimuli and monetary wins or losses. As expected, winning decreased pain perception compared to losing. Inter-individual differences in pain modulation by monetary wins relative to losses correlated with activation in the medial orbitofrontal cortex (mOFC). When pain and reward occured simultaneously, mOFCs functional connectivity changed: the signal time course in the mOFC condition-dependent correlated negatively with the signal time courses in the rostral anterior insula, anterior-dorsal cingulate cortex and primary somatosensory cortex, which might signify moment-to-moment down-regulation of these regions by the mOFC. Monetary wins and losses did not change the magnitude of pain-related activation, including in regions that code perceived pain intensity when nociceptive input varies and/or receive direct nociceptive input. Pain inhibition by reward appears to involve brain regions not typically involved in nociceptive intensity coding but likely mediate changes in the significance and/or value of pain.

Does the β-receptor antagonist esmolol have analgesic effects?: A randomised placebo-controlled cross-over study on healthy volunteers undergoing the cold pressor test.

Esmolol may attenuate the sympathetic response to pain and reduce postoperative opioid consumption. It is not clear whether esmolol has an analgesic effect per se. The aim of this study was to evaluate the analgesic effect of esmolol in the absence of anaesthetics and opioids. We tested the hypothesis that esmolol would reduce the maximum pain intensity perceived during the cold pressor test (CPT) by 2 points on a 0 to 10 numeric pain rating scale (NRS) compared to placebo. Randomised, placebo-controlled cross-over study. Postoperative recovery area, Örebro University Hospital. Study period, November 2013 to February 2014. Fourteen healthy volunteers. Exclusion criteria included ongoing medication, pregnancy and breastfeeding and participation in other medical trials. At separate study sessions, participants received interventions: esmolol (0.7 mg kg bolus over 1 min followed by infusion at 10 μg kg min); 0.9% normal saline bolus then remifentanil infusion at 0.2 μg kg min and 0.9% normal saline bolus and infusion according to a random sequence. All infusions were administered over 30 min. Perceived maximum pain intensity score, pain tolerance and haemodynamic changes during CPT, and occurrence of side-effects to interventions compared to placebo, respectively. Esmolol did not reduce perceived pain intensity or pain tolerance during the CPT. The NRS-max score was similar for esmolol, 8.5 (±1.4) and placebo, 8.4 (±1.3). The mean difference was 0.1 [95% confidence interval (-1.2 to 1.4)], P value equal to 0.83. Remifentanil significantly reduced NRS-max scores, 5.4 (±2.1) compared to placebo, [mean difference -3.1 (95% confidence interval (-4.4 to -1.8)), P < 0.001]. Side-effects were seen with remifentanil but not with esmolol. No direct analgesic effect of esmolol could be demonstrated in the present study. The postoperative opioid-sparing effect demonstrated in previous studies, could therefore be secondary to other factors such as avoidance of opioid-induced hyperalgesia, synergy with coadministered opioids or altered pharmacokinetics of those drugs. European clinical trials database, https://eudract.ema.europa.eu/, EudraCT no. 2011-005780-24.

Pain and discomfort during the first week of rapid maxillary expansion (RME) using two different RME appliances: A randomized controlled trial.

To evaluate and compare perceived pain intensity, discomfort, and jaw function impairment during the first week with tooth-borne or tooth-bone-borne rapid maxillary expansion (RME) appliances. Fifty-four patients (28 girls and 26 boys) with a mean age of 9.8 years (SD 1.28 years) were randomized into two groups. Group A received a conventional hyrax appliance and group B a hybrid hyrax appliance anchored on mini-implants in the anterior palate. Questionnaires were used to assess pain intensity, discomfort, analgesic consumption, and jaw function impairment on the first and fourth days after RME appliance insertion. Fifty patients answered both questionnaires. Overall median pain on the first day in treatment was 13.0 (range 0-82) and 3.5 (0-78) for groups A and B, respectively, with no significant differences in pain, discomfort, analgesic consumption, or functional jaw impairment between groups. Overall median pain on the fourth day was 9.0 (0-90) and 2.0 (0-71) for groups A and B, respectively, with no significant differences between groups. There were also no significant differences in pain levels within group A, while group B scored significantly lower concerning pain from molars and incisors and tensions from the jaw on day 4 than on the first day in treatment. There was a significant positive correlation between age and pain and discomfort on the fourth day in treatment. No correlations were found between sex and pain and discomfort, analgesic consumption, and jaw function impairment. Both tooth-borne and tooth-bone-borne RME were generally well tolerated by the patients during the first week of treatment.

Associations between Measures of Structural Morphometry and Sensorimotor Performance in Individuals with Nonspecific Low Back Pain.

To date, most structural brain imaging studies in individuals with nonspecific low back pain have evaluated volumetric changes. These alterations are particularly found in sensorimotor-related areas. Although it is suggested that specific measures, such as cortical surface area and cortical thickness, reflect different underlying neural architectures, the literature regarding these different measures in individuals with nonspecific low back pain is limited. Therefore, the current study was designed to investigate the association between the performance on a sensorimotor task, more specifically the sit-to-stand-to-sit task, and cortical surface area and cortical thickness in individuals with nonspecific low back pain and healthy controls. Seventeen individuals with nonspecific low back pain and 17 healthy controls were instructed to perform 5 consecutive sit-to-stand-to-sit movements as fast as possible. In addition, T1-weighted anatomic scans of the brain were acquired and analyzed with FreeSurfer. Compared with healthy controls, individuals with nonspecific low back pain needed significantly more time to perform 5 sit-to-stand-to-sit movements (P < .05). Brain morphometric analyses revealed that cortical thickness of the ventrolateral prefrontal cortical regions was increased in patients with nonspecific low back pain compared with controls. Furthermore, decreased cortical thickness of the rostral anterior cingulate cortex was associated with lower sit-to-stand-to-sit performance on an unstable support surface in individuals with nonspecific low back pain and healthy controls (r = -0.47, P < .007). In addition, a positive correlation was found between perceived pain intensity and cortical thickness of the superior frontal gyrus (r = 0.70, P < .002) and the pars opercularis of the inferior ventrolateral prefrontal cortex (r = 0.67, P < .004). Hence, increased cortical thickness was associated with increased levels of pain intensity in individuals with nonspecific low back pain. No associations were found between cortical surface area and the pain characteristics in this group. The current study suggests that cortical thickness may contribute to different aspects of sit-to-stand-to-sit performance and perceived pain intensity in individuals with nonspecific low back pain.

Effects of High-Dose Capsaicin on TMD Subjects: A Randomized Clinical Study.

Temporomandibular joint disorder (TMD) is a complex musculoskeletal disorder that presents with pain, limited jaw opening, and abnormal noises in the temporomandibular joint. Despite the significant impact that TMD has in terms of suffering and financial burden, relatively few new treatments have emerged; therefore, development of novel treatments to treat TMD pain remains a high priority. The rationale of this study was to use a double-blind, vehicle-controlled clinical trial to evaluate the effects of a high-concentration (8%) capsaicin cream on TMD. This is based on the hypothesis that targeting TRP vanilloid subfamily member 1 (TRPV1) for pain control may provide a novel method for pain relief in TMD patients. TRPV1 is primarily expressed on a population of nociceptive-specific neurons and provides a candidate target for the development of pain treatments. Capsaicin is the primary agonist for TRPV1 and has been used previously in relatively low doses (0.025% to 0.075%) as a therapeutic for a variety of pain disorders, including postherpetic neuralgia and osteoarthritis; however, analgesic efficacy remains equivocal. TMD and healthy control subjects were assigned to either an active capsaicin or vehicle control group. The treatments were applied for 2 h and then removed. Quantitative sensory testing (QST) was completed prior to drug application (baseline), 2 h after drug application, and 1 wk later. Perceived pain intensity was measured using a visual analog scale (VAS) following capsaicin or vehicle cream application. Significantly lower pain was reported in the week after application in the capsaicin-treated TMD subjects. For QST measures, there was a decreased thermal pain threshold 2 h after capsaicin application for both the control and TMD groups, but this resolved within a week. Capsaicin had no effect on pressure pain threshold or mechanical sensitivity in both TMD and healthy individuals. This study demonstrates that 8% topical capsaicin therapy is a relatively safe, simple, and effective treatment for patients with TMD. Knowledge Transfer Statement: This study evaluated a novel topical capsaicin therapy for reducing orofacial pain. The results of this study can be used to provide another treatment option for patients with TMD.

Pubic Bone Resection Provides Objective Pain Control in the Prostate Cancer Survivor With Pubic Bone Osteomyelitis With an Associated Urinary Tract to Pubic Symphysis Fistula

To investigate pain intensity perception in prostate cancer survivors with pubic bone osteomyelitis with an associated urinary tract to pubic symphysis fistula before and after definitive surgical management. We performed a review of an institutional review board-approved database of prostate cancer survivors with pubic bone osteomyelitis from 2010 to 2015. Demographic and clinical data were extracted. Pain scores were assessed in patients at varying points before and after definitive treatment using an 11-point numeric rating scale. Statistical analysis was performed using a Wilcoxon signed-rank test and NcNemar's test. We identified 16 patients with a median age of 72 who met inclusion criteria. Chronic narcotic use for pain management was noted in 6 of 16 (37.5%) patients preoperatively. No statistical difference was identified between the pain score at the time of diagnosis and after completion of conservative measures (5.5 vs 5.5, P = .76). A statistically significant decrease in median pain score at the first follow-up appointment was seen compared to the preoperative pain score (0 vs. 5.5, P = .0005). At a median follow-up of 9.4 months (interquartile range 3.7-16.5), a sustained decrease in the median pain intensity score was noted in our cohort compared to their preoperative baseline pain score (5.5 vs 0, P = .0005) and pain score at the time of diagnosis (5.5 vs 0, P = .004.) CONCLUSION: Pubic bone resection provides immediate and sustained improvement in pain intensity perception in the prostate cancer survivor with pubic bone osteomyelitis with an associated urinary tract to pubic symphysis fistula.

Spatial and Temporal Brain Responses to Noxious Heat Thermal Stimuli in Burning Mouth Syndrome

Burning mouth syndrome (BMS) is an idiopathic orofacial pain condition. Although the pathophysiology of BMS is not clearly understood, central and peripheral neuropathic mechanisms are thought to be involved. The authors compared brain response to noxious heat stimuli in 16 right-handed women with primary BMS and 15 sex- and age-matched right-handed healthy female controls. A thermal stimulus sequence of 32 °C to 40 °C to 32 °C to 49 °C was repeated 4 times in a cycle. Warm and noxious heat stimuli were delivered with a Peltier thermode placed on the right palm or right lower lip for 32 s each in a session. Functional magnetic resonance imaging data were obtained by recording echoplanar images with a block design. Statistical Parametric Mapping 8 software was used to analyze the data. Patients and controls both reported feeling more pain during palm stimulation than during lip stimulation. Repetition of noxious heat stimulus on the lower lip but not on the palm induced habituation in brain activity in the cingulate cortex without reduction in pain perception. Multiple regression analysis revealed a correlation between perceived pain intensity and suppression of brain activity in the anterior cingulate cortex when the repeated thermal sequence was applied at the lower lip. Furthermore, the response of the parahippocampal area differed in BMS patients and controls when the same repeated thermal sequence was applied at the palm. The authors’ findings indicate that BMS patients show specific brain responses due to impaired function of the central and peripheral nervous systems (clinical trial registration: UMIN000015002).

The effects of attachment style and security priming on the perception of others’ pain

Abundant evidence has demonstrated a relationship between adult attachment and the experience of one’s own pain. However, few studies have investigated the associations between adult attachment and perception of others’ pain. The current studies examined the effects of attachment style and security priming on the perception of others’ pain. In Study 1, we explored the influence of avoidant and anxious attachment styles on the perception of pain in pictures representing pain or no pain. The results indicated that individuals high on anxiety and low on avoidance (i.e., preoccupied attachment style) reported more pain intensity and unpleasantness for painful pictures; individuals high on both anxiety and avoidance (i.e., fearful attachment style) reported less pain intensity for painful pictures. In Study 2, we examined the effects of security priming and attachment style on the perception of pain in pictures representing pain or no pain by adopting a security priming paradigm. The results suggested that security priming attenuated perceived pain intensity for painful pictures for individuals with high attachment anxiety. In Study 3, we used another well-validated security priming paradigm; results indicated that security priming reduced perceived pain intensity for pain pictures among individuals high on anxiety and low on avoidance (i.e., preoccupied attachment style) but increased perceived pain intensity for painful pictures among individuals high on both anxiety and avoidance (i.e., fearful attachment style). Directions for future research, clinical implications, and limitations of the present studies are discussed.

Influence of Therapeutic Approach in the TENS-induced Hypoalgesia.

The present study aimed to determine how the therapist's approach about intervention may influence transcutaneous electrical nerve stimulation (TENS)-induced hypoalgesia. One hundred and sixty-one pain-free individuals agreed to participate in this study and had their demographics, perceived pain intensity, pressure pain threshold, anxiety level, and the state of anxiety inventory score measured. Subsequently, participants were randomly assigned into 6 study groups, 3 active and 3 placebo TENS associated with positive, negative, or neutral approaches about electrical stimulation, as given by the investigator. After the treatment, all parameters were reassessed. Active TENS-treated participants receiving either positive or neutral expectations about intervention showed a significant increase in pressure pain threshold (P<0.02) compared with pretreatment; however, this was not observed in the active TENS group when associated with negative expectations. The intensity of perceived pain was significantly reduced (P<0.02) only in the active TENS groups in association with either positive or neutral expectations. There was no significant difference in any of the variables assessed in the groups receiving placebo TENS intervention. The negative expectations induced prior to the proposed intervention promoted unfavorable outcomes with respect to the analgesic properties of TENS, suggesting that the approach taken by the physical therapist should be used to convey positive expectations and avoid those negatives, to promote more efficacious treatment.

Efficacy of Mindfulness-Based Cognitive Therapy on Late Post-Treatment Pain in Women Treated for Primary Breast Cancer: A Randomized Controlled Trial.

To assess the efficacy of mindfulness-based cognitive therapy (MBCT) for late post-treatment pain in women treated for primary breast cancer. A randomized wait list-controlled trial was conducted with 129 women treated for breast cancer reporting post-treatment pain (score ≥ 3 on pain intensity or pain burden assessed with 10-point numeric rating scales). Participants were randomly assigned to a manualized 8-week MBCT program or a wait-list control group. Pain was the primary outcome and was assessed with the Short Form McGill Pain Questionnaire 2 (SF-MPQ-2), the Present Pain Intensity subscale (the McGill Pain Questionnaire), and perceived pain intensity and pain burden (numeric rating scales). Secondary outcomes were quality of life (World Health Organization-5 Well-Being Index), psychological distress (the Hospital Depression and Anxiety Scale), and self-reported use of pain medication. All outcome measures were assessed at baseline, postintervention, and 3-month and 6-month follow-up. Treatment effects were evaluated with mixed linear models. Statistically significant time × group interactions were found for pain intensity (d = 0.61; P = .002), the Present Pain Intensity subscale (d = 0.26; P = .026), the SF-MPQ-2 neuropathic pain subscale (d = 0.24; P = .036), and SF-MPQ-2 total scores (d = 0.23; P = .036). Only pain intensity remained statistically significant after correction for multiple comparisons. Statistically significant effects were also observed for quality of life (d = 0.42; P = .028) and nonprescription pain medication use (d = 0.40; P = .038). None of the remaining outcomes reached statistical significance. MBCT showed a statistically significant, robust, and durable effect on pain intensity, indicating that MBCT may be an efficacious pain rehabilitation strategy for women treated for breast cancer. In addition, the effect on neuropathic pain, a pain type reported by women treated for breast cancer, further suggests the potential of MBCT but should be considered preliminary.

Multiple faces of pain: effects of chronic pain on the brain regulation of facial expression.

Pain behaviors are shaped by social demands and learning processes, and chronic pain has been previously suggested to affect their meaning. In this study, we combined functional magnetic resonance imaging with in-scanner video recording during thermal pain stimulations and use multilevel mediation analyses to study the brain mediators of pain facial expressions and the perception of pain intensity (self-reports) in healthy individuals and patients with chronic back pain (CBP). Behavioral data showed that the relation between pain expression and pain report was disrupted in CBP. In both patients with CBP and healthy controls, brain activity varying on a trial-by-trial basis with pain facial expressions was mainly located in the primary motor cortex and completely dissociated from the pattern of brain activity varying with pain intensity ratings. Stronger activity was observed in CBP specifically during pain facial expressions in several nonmotor brain regions such as the medial prefrontal cortex, the precuneus, and the medial temporal lobe. In sharp contrast, no moderating effect of chronic pain was observed on brain activity associated with pain intensity ratings. Our results demonstrate that pain facial expressions and pain intensity ratings reflect different aspects of pain processing and support psychosocial models of pain suggesting that distinctive mechanisms are involved in the regulation of pain behaviors in chronic pain.

Factors affecting acute pain perception and analgesics consumption in patients undergoing bariatric surgery

BackgroundPrevious studies performed in non-obese patients undergoing elective surgery have revealed that psychological factors may affect postoperative analgesic requirements. The aim of this observational prospective study was to investigate the extent to which psychopathological dimensions, including anxiety, depression and alexithymia, may influence postoperative pain intensity and analgesics consumption using patient-controlled analgesia (PCA) in patients undergoing bariatric surgery. Methods120 patients, aged 18–60years, with an ASA physical status I–II, undergoing gastric bypass were enrolled. Anxiety and depression Hamilton scales, and Toronto Alexithymia scale, were administered to patients on the day before surgery. General anesthesia was standardized. After awakening, a PCA pump with intravenous tramadol was immediately made available for a 36-hour postoperative analgesia. Visual analog scale at rest (VASr) and after coughing (VASi), and effective PCA requests number were postoperatively recorded. Pearson's correlations, Anova analyses and multiple linear regression were used for statistical purpose. ResultsPositive correlations were found between anxiety, depression, alexithymia and all pain indicators (p<0.01). Analyses of variance showed that anxious (p<0.001), depressed (p<0.001) and alexithymic (p<0.05) patients had high pain indicators. VASr and VASi were predicted by anxiety and depression (p<0.05), but not by alexithymia; effective PCA requests number was predicted by anxiety, depression and alexithymia (p<0.001). ConclusionsObese patients with high depression, anxiety and alexithymia levels rated their pain as more intense and required a larger amount of tramadol. Pain perception intensity was predicted by anxiety and depression but not by alexithymia, whereas analgesics consumption was predicted by all the investigated psychopathological dimensions.