Science.gov

Sample records for experimental pain study

  1. Study of experimental pain measures and nociceptive reflex in chronic pain patients and normal subjects.

    PubMed

    Boureau, F; Luu, M; Doubrère, J F

    1991-02-01

    This study evaluates (i) the effect of heterotopic chronic pain on various experimental pain measures, (ii) the relationship between experimental pain measures and chronic pain symptomatology assessment, and (iii) the influence of the various pain aetiologies on experimental pain measures. Fifty-three chronic pain patients were compared to 17 pain-free subjects with the following psychophysical and physiological indices: pain threshold (PTh), pain tolerance (PTol), verbal estimation of intensity and unpleasantness (intensity scale, IS; unpleasantness scale, US), threshold for intensity and unpleasantness (ITh and UTh), lower limb RIII nociceptive reflex (RIIITh and RIII frequency of occurrence). Chronic pain syndromes included neuropathic pain (n = 12), iodopathic pain (n = 12), myofascial syndromes (n = 9), headache (n = 9), and miscellaneous pain (n = 11). Chronic pain symptomatology was assessed with a visual analogue scale (VAS), a French MPQ adaptation (QDSA), Beck Depression Inventory (BDI), Spielberger State Trait Inventory (STAI) and Eysenck Personality Inventory (EPI). No significant difference was observed between chronic pain patients and pain-free control groups and between patient subgroups for PTh, PTol and RIIITh. No significant correlation was found between experimental pain measures and clinical pain, anxiety or depression scores. However, the chronic pain patients had a higher threshold for unpleasantness and judged the suprathreshold stimuli significantly less intense and less unpleasant than the control group. These results are discussed in relation to diffuse noxious inhibitory controls and the adaptation level theory of chronic pain experience.

  2. Heritability of pain catastrophizing and associations with experimental pain outcomes: a twin study.

    PubMed

    Trost, Zina; Strachan, Eric; Sullivan, Michael; Vervoort, Tine; Avery, Ally R; Afari, Niloofar

    2015-03-01

    This study used a twin paradigm to examine genetic and environmental contributions to pain catastrophizing and the observed association between pain catastrophizing and cold-pressor task (CPT) outcomes. Male and female monozygotic (n = 206) and dizygotic twins (n = 194) from the University of Washington Twin Registry completed a measure of pain catastrophizing and performed a CPT challenge. As expected, pain catastrophizing emerged as a significant predictor of several CPT outcomes, including cold-pressor Immersion Tolerance, Pain Tolerance, and Delayed Pain Rating. The heritability estimate for pain catastrophizing was found to be 37% with the remaining 63% of variance attributable to unique environmental influence. Additionally, the observed associations between pain catastrophizing and CPT outcomes were not found attributable to shared genetics or environmental exposure, which suggests a direct relationship between catastrophizing and experimental pain outcomes. This study is the first to examine the heritability of pain catastrophizing and potential processes by which pain catastrophizing is related to experimental pain response.

  3. Heritability of Pain Catastrophizing and Associations with Experimental Pain Outcomes: A Twin Study

    PubMed Central

    Trost, Zina; Strachan, Eric; Sullivan, Michael; Vervoort, Tine; Avery, Ally R.; Afari, Niloofar

    2014-01-01

    The current study employed a twin paradigm to examine the genetic and environmental contributions to pain catastrophizing as well as the observed association between pain catastrophizing and cold pressor task (CPT) outcomes. Male and female monozygotic (n=206) and dizygotic twins (n=194) from the University of Washington Twin Registry completed a measure of pain catastrophizing and performed a CPT challenge. As expected, pain catastrophizing emerged as a significant predictor of several CPT outcomes, including cold pressor immersion tolerance, pain tolerance, and delayed pain rating. The heritability estimate for pain catastrophizing was found to be 37% with the remaining 63% of variance attributable to unique environmental influence. Additionally, the observed associations between pain catastrophizing and CPT outcomes were not found attributable to shared genetics or environmental exposure, suggesting a direct relationship between catastrophizing and experimental pain outcomes. This study is the first to examine the heritability of pain catastrophizing and potential processes by which pain catastrophizing is related to experimental pain response. PMID:25599234

  4. Decreased pain sensitivity among people with schizophrenia: a meta-analysis of experimental pain induction studies.

    PubMed

    Stubbs, Brendon; Thompson, Trevor; Acaster, Sarah; Vancampfort, Davy; Gaughran, Fiona; Correll, Christoph U

    2015-11-01

    Patients with schizophrenia report reduced pain sensitivity in clinical studies, but experimental studies are required to establish pain sensitivity as a potential endophenotype. We conducted a systematic review of electronic databases from database inception until April 15, 2015, including experimental studies investigating pain among patients with schizophrenia spectrum disorder vs healthy controls. A random-effect meta-analysis yielding Hedges' g ±95% confidence intervals (CIs) as the effect size (ES) measure was conducted. Primary outcome was a pooled composite of pain threshold and pain tolerance; secondary outcomes included these parameters individually, plus sensory threshold, physiological pain response, and pain intensity or unpleasantness. Across 17 studies, patients with schizophrenia spectrum disorder (n = 387; age, 30.7 ± 6.9 years; females, 31.9%; illness duration, 7.0 ± 5.7 years) were compared with controls (n = 483; age, 29.5 ± 7.4 years; females, 31.0%). Patients had elevated pain threshold/pain tolerance vs controls (ES = 0.583; 95% CI, 0.212-0.954; P = 0.002; studies = 15). Results were similar in antipsychotic-free individuals (ES = 0.599; 95% CI, 0.291-0.907; P < 0.0001; studies = 8), with trend-level significance in antipsychotic-treated individuals (ES = 0.566; 95% CI, -0.007 to 1.125; P = 0.047; studies = 9). Likewise, patients with schizophrenia had increased pain tolerance (ES = 0.566; 95% CI, 0.235-0.897; P = 0.0001; studies = 6), sensory threshold (ES = 1.16; 95% CI, 0.505-1.727; P < 0.0001; studies = 5), and pain threshold (ES = 0.696; 95% CI, 0.407-0.986; P < 0.001; studies = 9), as well as reduced physiological response to noxious stimuli (ES = 0.456; 95% CI, 0.131-0.783; P = 0.006) and pain intensity/unpleasantness ratings (ES = 0.547; 95% CI, 0.146-0.949; P = 0.008). Findings were similarly significant in antipsychotic-free patients with schizophrenia (analysable parameters = 4) and antipsychotic-treated individuals (analysable

  5. Effects of mindfulness and distraction on pain depend upon individual differences in pain catastrophizing: an experimental study.

    PubMed

    Prins, B; Decuypere, A; Van Damme, S

    2014-10-01

    The aim of this study was to investigate whether the perception of experimental pain was different during a mindfulness manipulation than during a distraction manipulation. Furthermore, it was examined if effects were moderated by dispositional pain catastrophizing. Undergraduate students (n = 51) completed self-report measures of pain catastrophizing and mindfulness. Subsequently, they were administered a series of mildly painful heat stimuli, which they had to rate. During pain induction, participants listened to either a pre-recorded mindfulness instruction (mindfulness group) or a pre-recorded story (distraction group). After controlling for baseline experimental pain ratings, we found no overall group effect, indicating that there was no difference in experienced pain between the mindfulness group and the distraction group. However, a significant moderation effect was found. When dispositional pain catastrophizing was high, pain was less pronounced in the mindfulness group than in the distraction group, whereas the opposite effect was found when the level of pain catastrophizing was low. The findings suggest that in persons with a high level of catastrophic thinking about pain, mindfulness-based coping may be a better approach than distraction. © 2014 European Pain Federation - EFIC®

  6. Experimental pain induces attentional bias that is modified by enhanced motivation: An eye tracking study.

    PubMed

    Sun, Z-K; Wang, J-Y; Luo, F

    2016-09-01

    In this study, the effects of prior pain experience and motivation on attentional bias towards pain-related information were investigated within two visual-probe tasks via eye movement behaviours. It is hypothesized that pain experience would induce stronger attentional bias and such bias could be suppressed by the motivation to avoid impeding pain. All participants took part in visual-probe tasks with pictures and words as stimuli that are typically used in studies of attentional bias. They were allocated to three groups: no-pain (NP) group, performing tasks without experiencing pain; pain-experience (PE) group, performing the same tasks following painful stimuli; and pain-experience-with-motivation (PEM) group, undergoing the same procedure as PE group with additional instructions about avoiding impeding pain. Eye movements were recorded during the tasks. The eye movement data showed that: (1) participants in the PE group exhibited stronger attention bias towards painful pictures than those in the NP group; (2) the attentional bias towards painful pictures was significantly reduced in the PEM group as compared to the PE group. By contrast, the verbal task failed to find these effects using sensory pain words as stimuli. This study was the first that revealed the impact of acute experimental pain on attentional bias towards pain-related information in healthy individuals through eye tracking. It may provide a possible solution to reduce hypervigilance towards pain-related information by altering the motivational relevance. WHAT DOES THIS STUDY ADD?: (1) This study revealed the impact of experimental pain on attentional bias in healthy individuals; (2) This study may provide a possible approach of altering motivational relevance to control the pain-induced attentional bias towards pain-related information. © 2016 European Pain Federation - EFIC®

  7. Identifying experimental methods to determine the effect of pain on attention: a review of pain, caffeine, alcohol and nicotine studies.

    PubMed

    Moore, David J; Keogh, Edmund; Eccleston, Christopher

    2009-12-01

    To review published studies of the effects that pain and common psychopharmacological substances have on the attentional performance of healthy adults. To identify which attentional tasks have the greatest potential to investigate the effect of pain on attention and provide recommendations for future research. A search was conducted for reports of experimental studies of attention in the context of pain. This was supplemented with studies on attention and caffeine, nicotine and alcohol. Studies were included if they used a healthy adult sample, used experimental or quasi-experimental methods, were relevant to the study of attention or interruption of pain and/or examined the acute effects of a substance on attention. Thirty-two papers, with 49 different experimental studies were identified (12 pain, 21 nicotine, 7 caffeine, 9 alcohol). Fourteen different tasks were reviewed across six domains of attention. The most promising measures of attention were the continuous performance task, flanker task, endogenous pre-cuing task, n-back task, inhibition task and dual task. There are reliable tasks that could be used to determine the effects of pain on attention. Future research is required that develops the utility of these tasks to improve our understanding of the effects pain and analgesia have on attentional performance. Copyright (c) 2009 John Wiley & Sons, Ltd.

  8. Observational learning and pain-related fear: an experimental study with colored cold pressor tasks.

    PubMed

    Helsen, Kim; Goubert, Liesbet; Peters, Madelon L; Vlaeyen, Johan W S

    2011-12-01

    The primary aim of the current study was to experimentally test whether pain-related fear can be acquired through observational learning, whether extinction occurs after actual exposure to the aversive stimulus, and whether pain-related fear was associated with increased pain ratings. During an observation phase, female volunteers watched a video showing models performing cold pressor tasks (CPT), of which the color served as a conditioned stimulus (CS). In a differential fear conditioning paradigm, each of 2 colors were either paired with models' painful (CS+) or neutral (CS-) facial expressions. Exposure consisted of participants performing CPTs of both colors (10°C). Self-reported fear of pain and expected pain ratings were obtained after the observation period, while actual pain and avoidance measures were obtained during and after exposure. Results show that after observing another person performing the CPT associated with the painful faces, subjects report more fear of pain and expect more intense and unpleasant pain as compared with the CPT associated with the neutral faces. This effect of observational learning on pain-related fear persisted until after exposure. During and after exposure no stimulus-type effect for pain ratings was found. This study provides preliminary evidence for observational learning of pain-related fear in humans. Fear of pain can be more disabling than pain itself, and is a risk factor for chronic pain. Knowledge about the acquisition of pain-related fear may help to develop novel pain management programs. This study is one of the first to demonstrate the effects of observational learning on pain-related fear. Copyright © 2011 American Pain Society. Published by Elsevier Inc. All rights reserved.

  9. Nurses' response to pain communication from patients: a post-test experimental study.

    PubMed

    McDonald, Deborah Dillon; Laporta, Matthew; Meadows-Oliver, Mikki

    2007-01-01

    Inadequate communication about pain can result in increased pain for patients. The purpose of the current pilot study was to test how nurses respond when patients use their own words, a pain intensity scale, or both to communicate pain. A post-test only experimental design was used with three pain description conditions, personal and numeric; personal only; numeric only. The setting included six hospitals and one school of nursing located in the northeastern United States. PARTICIPANTS included 122 registered medical surgical nurses. Nurses were randomly assigned to condition, and read a vignette about a trauma patient with moderately severe pain. The vignettes were identical except for the patient's pain description and age. The nurses then wrote how they would respond to the patient's pain. Two blind raters content analyzed the responses, giving nurses one point for including each of six a priori criteria derived from the Acute Pain Management Panel [1992. Acute Pain Management: operative or medical procedures and trauma. Clinical practice guideline (AHCPR Publication No. 92-0032)., Rockville, MD, USA] and the American Pain Society [2003. Principles of analgesic use in the treatment of acute pain and cancer pain, Glenville, IL, USA]. Nurses planned similar numbers of pain management strategies across the three conditions, with a mean of 2.1 (SD=1.14) strategies out of the recommended six. Nurses did not respond with more pain management strategies when patients describe pain in their own words, or in their own words and a pain intensity scale. The relatively small number of pain management strategies planned by the nurses suggests that nurses use few strategies to respond to moderately severe pain problems.

  10. Experimental endotoxemia as a model to study neuroimmune mechanisms in human visceral pain.

    PubMed

    Benson, Sven; Engler, Harald; Schedlowski, Manfred; Elsenbruch, Sigrid

    2012-07-01

    The administration of bacterial endotoxin (i.e., lipopolysaccharide, LPS) constitutes a well-established experimental approach to study the effects of an acute and transient immune activation on physiological, behavioral, and emotional aspects of sickness behavior in animals and healthy humans. However, little is known about possible effects of experimental endotoxemia on pain in humans. This knowledge gap is particularly striking in the context of visceral pain in functional as well as chronic-inflammatory gastrointestinal disorders. Although inflammatory processes have been implicated in the pathophysiology of visceral pain, it remains incompletely understood how inflammatory mediators interact with bottom-up (i.e., increased afferent input) and top-down (i.e., altered central pain processing) mechanisms of visceral hyperalgesia. Considering the recent findings of visceral hyperalgesia after LPS application in humans, in this review, we propose that experimental endotoxemia with its complex peripheral and central effects constitutes an experimental model to study neuroimmune communication in human pain research. We summarize and attempt to integrate relevant animal and human studies concerning neuroimmune communication in visceral and somatic pain, discuss putative mechanisms, and conclude with future research directions. © 2012 New York Academy of Sciences.

  11. Abnormal Pain Response to Visual Feedback During Cervical Movements in Chronic Whiplash: An Experimental Study.

    PubMed

    De Kooning, Margot; Daenen, Liesbeth; Verhelpen, Sam; Don, Sanneke; Voogt, Lennard; Roussel, Nathalie; Ickmans, Kelly; Van Loo, Michel; Cras, Patrick; Nijs, Jo

    2017-02-01

    Whiplash-associated disorders (WAD) are a debilitating condition. In chronic WAD, sensorimotor incongruence exacerbates symptoms. Sensorimotor incongruence occurs when somatosensory input and predicted motor output are in conflict, which can trigger pain. On the other hand, there is evidence that visual feedback can decrease pain in certain chronic pain conditions. Therefore, the aim of this study was to examine the effect of visual feedback and sensorimotor incongruence on pain thresholds in chronic WAD. Sixty-four participants (healthy controls and patients with chronic WAD) were subjected to six experimental conditions. Participants watched correct real-time or modified visual feedback of the neck or hand (without movement as well as during repetitive neck lateroflexion). Sensorimotor incongruence was induced by manipulating visual feedback. Pressure pain thresholds were measured at baseline and during each condition. Marked between-group differences were observed. Visual feedback of the neck-correct or modified-did not influence pain thresholds in chronic WAD. In contrast, healthy controls had significantly higher pain thresholds when provided with the correct or modified visual feedback. When a movement of the neck was added during visual feedback, patients with chronic WAD showed no significant difference in pain thresholds, while an increase in pain thresholds was found in the healthy control group. In contrast to the healthy controls, visual feedback and sensorimotor incongruence did not alter pain thresholds in patients with chronic WAD. These findings suggest an abnormal pain response to visual feedback and somatosensory incongruence as well as failing mechanisms of pain inhibition in chronic WAD. © 2016 World Institute of Pain.

  12. The effect of paracetamol and tropisetron on pain: experimental studies and a review of published data.

    PubMed

    Tiippana, Elina; Hamunen, Katri; Kontinen, Vesa; Kalso, Eija

    2013-02-01

    Experimental studies suggest that paracetamol-induced analgesia is mediated via central serotonergic pathways and attenuated by 5-HT3-antagonists. However, clinical studies do not support this, and 5-HT3-antagonists are expected to reduce pain by blocking the descending pronociceptive pathway. The current project tested whether tropisetron attenuates analgesia by paracetamol. Two randomized, double-blind, crossover studies with 18 healthy male volunteers in each were performed. Pain stimuli were cold water immersion (cold pressor test), contact heat pain (study 1) and electrical stimulation (study 2). In both studies, tropisetron 5 mg i.v. or saline was administered, followed by paracetamol 2 g i.v. 30 min. later. Individual changes in heat and cold pain intensity, cold pain tolerance and unpleasantness were recorded. The same thresholds were also expressed as scores (% of the individual score at baseline). Additionally, previously published findings on the effects of paracetamol and its interaction with 5HT3-antagonists in human experimental pain models were reviewed. After calculation of the sensory and pain scores (%), tropisetron seemed to amplify the analgesic action of paracetamol. Paracetamol 2 g i.v. did not show any statistically significant analgesia in thermal tests (study 1), or differences in sensory, pain detection or moderate pain thresholds of the electrical stimulus (study 2). As paracetamol did not have a measurable analgesic effect in these tests, no conclusions can be drawn about the interaction between paracetamol and tropisetron. However, tropisetron may have an analgesic effect of its own. Clinicians should not avoid using these drugs together, unless larger clinical studies indicate otherwise.

  13. The role of motivation in distracting attention away from pain: an experimental study.

    PubMed

    Verhoeven, Katrien; Crombez, Geert; Eccleston, Christopher; Van Ryckeghem, Dimitri M L; Morley, Stephen; Van Damme, Stefaan

    2010-05-01

    Research on the effectiveness of distraction as a method of pain control is inconclusive. One mechanism pertains to the motivational relevance of distraction tasks. In this study the motivation to engage in a distraction task during pain was experimentally manipulated. Undergraduate students (N=73) participated in a cold pressor test (CPT) and were randomly assigned to three groups: a distraction-only group performed a tone-detection task during the CPT, a motivated-distraction group performed the same task and received a monetary reward for good task performance, and a control group did not perform the tone-detection task. Results indicated that engagement in the distraction task was better in the motivated-distraction group in comparison with the distraction-only group. Participants in both distraction groups experienced less pain compared to the control group. There were no overall differences in pain intensity between the two distraction groups. The effect of distraction was influenced by the level of catastrophic thinking about pain. For low catastrophizers, both distraction groups reported less pain as compared to the non-distracted control group. This was not the case for high catastrophizers. For high catastrophizers it mattered whether the distraction task was motivationally relevant: high catastrophizers reported less intense pain in the motivated-distraction group, as compared to the non-distracted control group. We conclude that increasing the motivational relevance of the distraction task may increase the effects of distraction, especially for those who catastrophize about pain. Copyright 2010 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

  14. Past Pain Experience and Experimentally induced Pain Perception.

    PubMed

    Paquet, Aude; Plansont, Brigitte; Labrunie, Anaïs; Malauzat, Dominique; Girard, Murielle

    2017-08-02

    Many intercurrent factors may be involved in the modulation of the pain message and its expression, such as the previous experience of pain built along the life. In this study, we aimed to determine whether susceptibility to experimentally induced pain is differentially influenced by the individual previous painful experience in subjects with schizophrenia (SC) major depression (MD), and controls (C). The SC (30), MD (32) and C (30) groups participated in experimental pain tests (application of pressure and induction of ischemia) after a semi-structured interview to make an inventory of the previous painful experiences, and the evaluation of anxiety either with autonomic (heart rate, blood pressure) or psychological (Hospital Anxiety Depression scale HAD) measures, and catastrophism. The reported pain intensities, severities, duration, of the previous pain events, and the number of previous painful events were equivalent in the three groups, except for the number of painful events experimented before the last six months which was lower in the MD group. Experimental pain sensitivity was influenced by the diagnosis, the HAD scores or the number and intensities of previous lived painful events. The lack of a past experience of pain was comparable for the different groups, suggesting that psychiatric disorders do not affect the experience of pain associated with daily life or past events. For each subject, the reported previous experience of pain influences the present feeling of pain.

  15. No effect of a single session of transcranial direct current stimulation on experimentally induced pain in patients with chronic low back pain--an exploratory study.

    PubMed

    Luedtke, Kerstin; May, Arne; Jürgens, Tim P

    2012-01-01

    Transcranial direct current stimulation (tDCS) has been shown to modulate cortical excitability. A small number of studies suggested that tDCS modulates the response to experimental pain paradigms. No trials have been conducted to evaluate the response of patients already suffering from pain, to an additional experimental pain before and after tDCS. The present study investigated the effect of a single session of anodal, cathodal and sham stimulation (15 mins/1 mA) over the primary motor cortex on the perceived intensity of repeated noxious thermal and electrical stimuli and on elements of quantitative sensory testing (thermal pain and perception thresholds) applied to the right hand in 15 patients with chronic low back pain. The study was conducted in a double-blind sham-controlled and cross-over design. No significant alterations of pain ratings were found. Modalities of quantitative sensory testing remained equally unchanged. It is therefore hypothesized that a single 15 mins session of tDCS at 1 mA may not be sufficient to alter the perception of experimental pain and in patients with chronic pain. Further studies applying repetitive tDCS to patients with chronic pain are required to fully answer the question whether experimental pain perception may be influenced by tDCS over the motor cortex.

  16. No Effect of a Single Session of Transcranial Direct Current Stimulation on Experimentally Induced Pain in Patients with Chronic Low Back Pain – An Exploratory Study

    PubMed Central

    Luedtke, Kerstin; May, Arne; Jürgens, Tim P.

    2012-01-01

    Transcranial direct current stimulation (tDCS) has been shown to modulate cortical excitability. A small number of studies suggested that tDCS modulates the response to experimental pain paradigms. No trials have been conducted to evaluate the response of patients already suffering from pain, to an additional experimental pain before and after tDCS. The present study investigated the effect of a single session of anodal, cathodal and sham stimulation (15 mins/1 mA) over the primary motor cortex on the perceived intensity of repeated noxious thermal and electrical stimuli and on elements of quantitative sensory testing (thermal pain and perception thresholds) applied to the right hand in 15 patients with chronic low back pain. The study was conducted in a double-blind sham-controlled and cross-over design. No significant alterations of pain ratings were found. Modalities of quantitative sensory testing remained equally unchanged. It is therefore hypothesized that a single 15 mins session of tDCS at 1 mA may not be sufficient to alter the perception of experimental pain and in patients with chronic pain. Further studies applying repetitive tDCS to patients with chronic pain are required to fully answer the question whether experimental pain perception may be influenced by tDCS over the motor cortex. PMID:23189136

  17. A method for studying jaw muscle activity during standardized jaw movements under experimental jaw muscle pain.

    PubMed

    Sae-Lee, Daraporn; Wanigaratne, Kamal; Whittle, Terry; Peck, Christopher C; Murray, Greg M

    2006-10-30

    This paper describes a method for studying superficial and deep jaw muscle activity during standardized jaw movements under experimental jaw muscle pain. In 22 healthy adults, pain was elicited in the right masseter muscle via tonic infusion of 4.5% hypertonic saline and which resulted in scores of 30-60 mm on a 100-mm visual analogue scale. Subjects performed tasks in five sessions in a repeated measures design, i.e., control 1, test 1 (during hypertonic or isotonic saline infusion), control 2 (without infusion), test 2 (during isotonic or hypertonic saline infusion), control 3 (without infusion). During each session, subjects performed maximal clenching and standardized jaw tasks, i.e., protrusion, lateral excursion, open/close, chewing. Mandibular movement was recorded with a 6-degree-of-freedom tracking system simultaneously with electromyographic (EMG) activity from the inferior head of the lateral pterygoid muscle with fine-wire electrodes (verified by computer tomography), and from posterior temporalis, the submandibular muscle group and bilateral masseter muscles with surface electrodes. EMG root mean square values were calculated at each 0.5 mm increment of mandibular incisor movement for all tasks under each experimental session. This establishes an experimental model for testing the effects of pain on jaw muscle activity where the jaw motor system is required to perform goal-directed tasks, and therefore should extend our understanding of the effects of pain on the jaw motor system.

  18. Effect of pulsed electromagnetic field therapy on experimental pain: A double-blind, randomized study in healthy young adults.

    PubMed

    Beaulieu, Karen; Beland, Patricia; Pinard, Marilee; Handfield, Guilène; Handfield, Nicole; Goffaux, Philippe; Corriveau, Hélène; Léonard, Guillaume

    2016-01-01

    Previous studies suggested that pulsed electromagnetic field (PEMF) therapy can decrease pain. To date, however, it remains difficult to determine whether the analgesic effect observed in patients are attributable to a direct effect of PEMF on pain or to an indirect effect of PEMF on inflammation and healing. In the present study, we used an experimental pain paradigm to evaluate the direct effect of PEMF on pain intensity, pain unpleasantness, and temporal summation of pain. Twenty-four healthy subjects (mean age 22 ± 2 years; 9 males) participated in the experiment. Both real and sham PEMF were administered to every participant using a randomized, double-blind, cross-over design. For each visit, PEMF was applied for 10 minutes on the right forearm using a portable device. Experimental pain was evoked before (baseline) and after PEMF with a 9 cm(2) Pelletier-type thermode, applied on the right forearm (120 s stimulation; temperature individually adjusted to produce moderate baseline pain). Pain intensity and unpleasantness were evaluated using a 0-100 numerical pain rating scale. Temporal summation was evaluated by comparing pain intensity ratings obtained at the end of tonic nociceptive stimulation (120 s) with pain intensity ratings obtained after 60 s of stimulation. When compared to baseline, there was no change in pain intensity and unpleasantness following the application of real or sham PEMF. PEMF did not affect temporal summation. The present observations suggest that PEMF does not directly influence heat pain perception in healthy individuals.

  19. Mere intention to perform painful movements elicits fear of movement-related pain: an experimental study on fear acquisition beyond actual movements.

    PubMed

    Meulders, Ann; Vlaeyen, Johan W S

    2013-04-01

    Fresh empirical evidence supports the notion that fear of movement-related pain can be acquired through associative learning. In the context of these findings, 2 ideas are appealing, yet uninvestigated. The first is that merely the intention to perform a painful movement acts as a covert conditioned stimulus (CS) inducing defensive fear responses (ie, gaining excitatory properties following Pavlovian acquisition). The second idea is that after extinction, fear of movement-related pain can easily be reinstated after unexpected painful stimuli (ie, reinstatement). In a voluntary differential conditioning movement paradigm with movements as CSs and a painful electrocutaneous stimulus as the unconditioned stimulus (pain-US), 2 groups were included (Experimental/Control). One movement (CS+) was followed by the pain-US and another movement (CS-) was not during acquisition, while the CS+ was no longer reinforced during extinction. Next, the Experimental group received 2 reinstating pain-USs, whereas the Control group did not. The CS+ but not the CS- evoked fear of movement-related pain in self-reports and eye-blink startles. Intriguingly, the mere intention to perform the painful movement produced higher eye-blink startle responses than the intention to perform the nonpainful movement. We also demonstrated nondifferential reinstatement in the verbal fear ratings in the Experimental group only. This study demonstrates that the mere intention to perform a painful movement prior to the actual painful movement itself can come to elicit conditioned fear responses. These results suggest that actual movement may not be necessary to elicit pain-related fear responses, maintaining chronic pain-related fear, avoidance, and disability. Copyright © 2013 American Pain Society. Published by Elsevier Inc. All rights reserved.

  20. Experimental tooth clenching. A model for studying mechanisms of muscle pain.

    PubMed

    Dawson, Andreas

    2013-01-01

    The overall goal of this thesis was to broaden knowledge of pain mechanisms in myofascial temporomandibular disorders (M-TMD). The specific aims were to: Develop a quality assessment tool for experimental bruxism studies (study I). Investigate proprioceptive allodynia after experimental tooth clenching exercises (study II). Evaluate the release of serotonin (5-HT), glutamate, pyruvate, and lactate in healthy subjects (study III) and in patients with M-TMD (study IV), after experimental tooth clenching exercises. In (I), tool development comprised 5 steps: (i) preliminary decisions, (ii) item generation, (iii) face-validity assessment, (iv) reliability and discriminative validity testing, and (v) instrument refinement. After preliminary decisions and a literature review, a list of 52 items to be considered for inclusion in the tool was generated. Eleven experts were invited to participate on the Delphi panel, of which 10 agreed. After four Delphi rounds, 8 items remained and were included in the Quality Assessment Tool for Experimental Bruxism Studies (Qu-ATEBS). Inter-observer reliability was acceptable (k = 0.77), and discriminative validity high (phi coefficient 0.79; P < 0.01). During refinement, 1 item was removed; the final tool comprised 7 items. In (II), 16 healthy females participated in three 60-min sessions, each with 24- and 48-h follow-ups. Participants were randomly assigned to a repetitive experimental tooth clenching task with a clenching level of 10%, 20%, or 40% of maximal voluntary clenching force (MVCF). Pain intensity, fatigue, perceived intensity of vibration (PIV), perceived discomfort (PD), and pressure pain threshold (PPT) were measured throughout. A significant increase in pain intensity and fatigue but not in PD was observed over time. A significant increase in PIV was only observed at 40 min, and PPT decreased significantly over time at 50 and 60 min compared to baseline. In (III), 30 healthy subjects (16 females, and 14 males

  1. Impact of a novel online learning module on specialist palliative care nurses' pain assessment competencies and patients' reports of pain: Results from a quasi-experimental pilot study.

    PubMed

    Phillips, Jane L; Heneka, Nicole; Hickman, Louise; Lam, Lawrence; Shaw, Tim

    2014-06-01

    Pain is a complex multidimensional phenomenon moderated by consumer, provider and health system factors. Effective pain management cuts across professional boundaries, with failure to screen and assess contributing to the burden of unrelieved pain. To test the impact of an online pain assessment learning module on specialist palliative care nurses' pain assessment competencies, and to determine whether this education impacted positively on palliative care patients' reported pain ratings. A quasi-experimental pain assessment education pilot study utilising 'Qstream(©)', an online methodology to deliver 11 case-based pain assessment learning scenarios, developed by an interdisciplinary expert panel and delivered to participants' work emails over a 28-day period in mid-2012. The 'Self-Perceived Pain Assessment Competencies' survey and chart audit data, including patient-reported pain intensity ratings, were collected pre-intervention (T1) and post-intervention (T2) and analysed using inferential statistics to determine key outcomes. Nurses working at two Australian inpatient specialist palliative care services in 2012. The results reported conform to the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) Guidelines. Participants who completed the education intervention ( n = 34) increased their pain assessment knowledge, assessment tool knowledge and confidence to undertake a pain assessment ( p < 0.001). Participants were more likely to document pain intensity scores in patients' medical records than non-participants (95% confidence interval = 7.3%-22.7%, p = 0.021). There was also a significant reduction in the mean patient-reported pain ratings between the admission and audit date at post-test of 1.5 (95% confidence interval = 0.7-2.3) units in pain score. This pilot confers confidence of the education interventions capacity to improve specialist palliative care nurses' pain assessment practices and to reduce patient-rated pain intensity

  2. The role of neuroplasticity in experimental neck pain: a study of potential mechanisms impeding clinical outcomes of training.

    PubMed

    Rittig-Rasmussen, Bjarne; Kasch, Helge; Fuglsang-Frederiksen, Anders; Svensson, Peter; Jensen, Troels Staehelin

    2014-08-01

    Training is a mainstay in the clinical management of neck pain, yet, effects of various training protocols are only small to moderate and improvements are required. Previous investigations of the nervous system indicate a correlation between neuroplastic adaptation to training and functional recovery. The interaction between neck pain and training thus needs further exploration. This was a randomized experimental study of the effects of experimental neck pain and training on corticomotor excitability. Healthy volunteers were randomized to training and experimental neck pain, training and no pain, and pain and no training. Primary endpoints were corticomotor excitability assessed by transcranial magnetic stimulation and electromyography measured as changes in amplitudes and latencies of motor evoked potentials (MEPs), recorded at baseline and after 30 min, 1 h, and 1 week. Additionally, correlations between changes in MEPs and motor learning, effects of pain and concomitant neck training on pain, muscle strength, and fatigue were investigated. Data were analyzed by repeated measurement ANOVA, paired t tests, Grubbs' outlier test and correlation coefficients. Results indicated that neck pain and training significantly enhanced the inhibition of the amplitudes of the MEPs for 1 week. The results indicate that moderate neck pain and training induce long-lasting inhibition of the corticomotor pathways. This inhibition may limit the outcome of neck training in painful conditions in contrast to pain-free training conditions.

  3. Pain in experimental autoimmune encephalitis: a comparative study between different mouse models

    PubMed Central

    2012-01-01

    Background Pain can be one of the most severe symptoms associated with multiple sclerosis (MS) and develops with varying levels and time courses. MS-related pain is difficult to treat, since very little is known about the mechanisms underlying its development. Animal models of experimental autoimmune encephalomyelitis (EAE) mimic many aspects of MS and are well-suited to study underlying pathophysiological mechanisms. Yet, to date very little is known about the sensory abnormalities in different EAE models. We therefore aimed to thoroughly characterize pain behavior of the hindpaw in SJL and C57BL/6 mice immunized with PLP139-151 peptide or MOG35-55 peptide respectively. Moreover, we studied the activity of pain-related molecules and plasticity-related genes in the spinal cord and investigated functional changes in the peripheral nerves using electrophysiology. Methods We analyzed thermal and mechanical sensitivity of the hindpaw in both EAE models during the whole disease course. Qualitative and quantitative immunohistochemical analysis of pain-related molecules and plasticity-related genes was performed on spinal cord sections at different timepoints during the disease course. Moreover, we investigated functional changes in the peripheral nerves using electrophysiology. Results Mice in both EAE models developed thermal hyperalgesia during the chronic phase of the disease. However, whereas SJL mice developed marked mechanical allodynia over the chronic phase of the disease, C57BL/6 mice developed only minor mechanical allodynia over the onset and peak phase of the disease. Interestingly, the magnitude of glial changes in the spinal cord was stronger in SJL mice than in C57BL/6 mice and their time course matched the temporal profile of mechanical hypersensitivity. Conclusions Diverse EAE models bearing genetic, clinical and histopathological heterogeneity, show different profiles of sensory and pathological changes and thereby enable studying the mechanistic basis

  4. Sacroiliac joint pain: Prospective, randomised, experimental and comparative study of thermal radiofrequency with sacroiliac joint block.

    PubMed

    Cánovas Martínez, L; Orduña Valls, J; Paramés Mosquera, E; Lamelas Rodríguez, L; Rojas Gil, S; Domínguez García, M

    2016-05-01

    To compare the analgesic effects between the blockade and bipolar thermal radiofrequency in the treatment of sacroiliac joint pain. Prospective, randomised and experimental study conducted on 60 patients selected in the two hospitals over a period of nine months, who had intense sacroiliac joint pain (Visual Analogue Scale [VAS]>6) that lasted more than 3 months. Patients were randomised into three groups (n=20): Group A (two intra-articular sacroiliac injections of local anaesthetic/corticosteroid guided by ultrasound in 7 days). Group B: conventional bipolar radiofrequency "palisade". Target points were the lateral branch nerves of S1, S2, and S3, distance needles 1cm. Group C: modified bipolar radiofrequency "palisade" (needle distance >1cm). Patients were evaluated at one month, three months, and one year. Demographic data, VAS reduction, and side effects of the techniques were assessed. One month after the treatment, pain reduction was >50% in the three groups P<.001. Three and 12 months after the technique, the patients of the group A did not have a significant reduction in pain. At 3 months, almost 50% patients of the group B referred to improvement of the pain (P=.03), and <25% at 12 months, and those results were statistically significant (P=.01) compared to the baseline. Group C showed an improvement of 50% at 3 and 12 months (P<.001). All patients completed the study. Bipolar radiofrequency "palisade", especially when the distance between the needles was increased, was more effective and lasted longer, compared to join block and steroids, in relieving pain sacroiliac joint. Copyright © 2015 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.

  5. Length of perineal pain relief after ice pack application: A quasi-experimental study.

    PubMed

    de Souza Bosco Paiva, Caroline; Junqueira Vasconcellos de Oliveira, Sonia Maria; Amorim Francisco, Adriana; da Silva, Renata Luana; de Paula Batista Mendes, Edilaine; Steen, Mary

    2016-04-01

    Ice pack is effective for alleviating postpartum perineal pain in primiparous women while multiparous women's levels of perineal pain appear to be poorly explored. Ice pack is a low-cost non-invasive localised treatment that can be used with no impact on breastfeeding. However, how long perineal analgesia persists after applying an ice pack is still unknown. To evaluate if perineal analgesia is maintained up to 2h after applying an ice pack to the perineum for 20min. A quasi-experimental study, using a pre and post-test design, was undertaken with a sample size of 50 multiparous women in Brazil. Data was collected by structured interview. The intervention involved a single application of an ice pack applied for 20min to the perineal area of women who reported perineal pain ≥3 by use of a numeric rating scale (0-10), with intact perineum, 1st or 2nd degree lacerations or episiotomy, between 6 and 24h after spontaneous vaginal birth. Perineal pain was evaluated at three points of time: before, immediately after and 2h after applying an ice pack. Immediately after applying an ice pack to the perineal area, there was a significant reduction in the severity of perineal pain reported (5.4 vs. 1.0, p<0.0005), which continued for 1h 35min up to 2h after the local application. Ice pack application for 20min is effective for alleviating postpartum perineal pain and continues to be effective between 1h 35min for up to 2h. Copyright © 2015 Australian College of Midwives. Published by Elsevier Ltd. All rights reserved.

  6. Anxiety measures during induced experimental pain.

    PubMed

    Coulthard, P; Rood, J P

    1993-01-01

    Results of analgesic studies obtained using experimental pain are often not comparable with those obtained from clinical studies. This may be because anxiety, which plays an important role in the pain experience, may not be evoked by experimentally induced pain. The aim of this study is to measure the level of anxiety induced by the submaximum effort tourniquet technique, which produces pain similar in quality to clinical pain. The mean time that subjects tolerated the pain from the tourniquet was 14.94 minutes. Systolic blood pressure and heart rate increased. Visual analogue scale measures of anxiety showed an overall increase during the experiment but were highly erratic individually. This study suggests that the submaximum effort tourniquet technique is incapable of inducing the same type of anxiety experienced with clinical pain.

  7. Indirect acquisition of pain-related fear: an experimental study of observational learning using coloured cold metal bars.

    PubMed

    Helsen, Kim; Vlaeyen, Johan W S; Goubert, Liesbet

    2015-01-01

    Previous research has demonstrated that pain-related fear can be acquired through observation of another's pain behaviour during an encounter with a painful stimulus. The results of two experimental studies were presented, each with a different pain stimulus, of which the aim was to investigate the effect of observational learning on pain expectancies, avoidance behaviour, and physiological responding. Additionally, the study investigated whether certain individuals are at heightened risk to develop pain-related fear through observation. Finally, changes in pain-related fear and pain intensity after exposure to the feared stimulus were examined. During observational acquisition, healthy female participants watched a video showing coloured cold metal bars being placed against the neck of several models. In a differential fear conditioning paradigm, one colour was paired with painful facial expressions, and another colour was paired with neutral facial expressions of the video models. During exposure, both metal bars with equal temperatures (-25° or +8° Celsius) were placed repeatedly against participants' own neck. Results showed that pain-related beliefs can be acquired by observing pain in others, but do not necessarily cause behavioural changes. Additionally, dispositional empathy might play a role in the acquisition of these beliefs. Furthermore, skin conductance responses were higher when exposed to the pain-associated bar, but only in one of two experiments. Differential pain-related beliefs rapidly disappeared after first-hand exposure to the stimuli. This study enhances our understanding of pain-related fear acquisition and subsequent exposure to the feared stimulus, providing leads for pain prevention and management strategies.

  8. Indirect Acquisition of Pain-Related Fear: An Experimental Study of Observational Learning Using Coloured Cold Metal Bars

    PubMed Central

    Helsen, Kim; Vlaeyen, Johan W. S.; Goubert, Liesbet

    2015-01-01

    Background Previous research has demonstrated that pain-related fear can be acquired through observation of another’s pain behaviour during an encounter with a painful stimulus. The results of two experimental studies were presented, each with a different pain stimulus, of which the aim was to investigate the effect of observational learning on pain expectancies, avoidance behaviour, and physiological responding. Additionally, the study investigated whether certain individuals are at heightened risk to develop pain-related fear through observation. Finally, changes in pain-related fear and pain intensity after exposure to the feared stimulus were examined. Methods During observational acquisition, healthy female participants watched a video showing coloured cold metal bars being placed against the neck of several models. In a differential fear conditioning paradigm, one colour was paired with painful facial expressions, and another colour was paired with neutral facial expressions of the video models. During exposure, both metal bars with equal temperatures (-25° or +8° Celsius) were placed repeatedly against participants’ own neck. Results Results showed that pain-related beliefs can be acquired by observing pain in others, but do not necessarily cause behavioural changes. Additionally, dispositional empathy might play a role in the acquisition of these beliefs. Furthermore, skin conductance responses were higher when exposed to the pain-associated bar, but only in one of two experiments. Differential pain-related beliefs rapidly disappeared after first-hand exposure to the stimuli. Conclusions This study enhances our understanding of pain-related fear acquisition and subsequent exposure to the feared stimulus, providing leads for pain prevention and management strategies. PMID:25806969

  9. Can personality traits and gender predict the response to morphine? An experimental cold pain study.

    PubMed

    Pud, Dorit; Yarnitsky, David; Sprecher, Elliot; Rogowski, Zeev; Adler, Rivka; Eisenberg, Elon

    2006-02-01

    The aim of the present study was to examine the possible role of personality traits, in accordance with Cloninger's theory, and gender, in the variability of responsiveness to opioids. Specifically, it was intended to test whether or not the three personality dimensions - harm avoidance (HA), reward dependence (RD) and novelty seeking (NS) - as suggested by Cloninger, can predict inter-personal differences in responsiveness to morphine after exposure to experimental cold pain. Thirty-four healthy volunteers (15 females, 19 males) were given the cold pressor test (CPT). Pain threshold, tolerance, and magnitude (VAS) were measured before and after (six measures, 30 min apart) the administration of either 0.5 mg/kg oral morphine sulphate (n=21) or 0.33 mg/kg oral active placebo (diphenhydramine) (n=13) in a randomized, double blind design. Assessment of the three personality traits, according to Cloninger's Tridimensional Personality Questionnaire, was performed before the CPT. A high HA score (but not RD, NS, or baseline values of the three pain parameters) predicted a significantly larger pain relief following the administration of morphine sulphate (but not of the placebo). Women exhibited a larger response in response to both treatments, as indicated by a significantly increased threshold and tolerance following morphine sulphate as well as significantly increased tolerance and decreased magnitude following placebo administration. The present study confirms the existence of individual differences in response to analgesic treatment. It suggests that high HA personality trait is associated with better responsiveness to morphine treatment, and that females respond better than men to both morphine and placebo.

  10. Vicarious pain while observing another in pain: an experimental approach

    PubMed Central

    Vandenbroucke, S.; Crombez, G.; Van Ryckeghem, D. M. L.; Brass, M.; Van Damme, S.; Goubert, L.

    2013-01-01

    Objective: This study aimed at developing an experimental paradigm to assess vicarious pain experiences. We further explored the putative moderating role of observer's characteristics such as hypervigilance for pain and dispositional empathy. Methods: Two experiments are reported using a similar procedure. Undergraduate students were selected based upon whether they reported vicarious pain in daily life, and categorized into a pain responder group or a comparison group. Participants were presented a series of videos showing hands being pricked whilst receiving occasionally pricking (electrocutaneous) stimuli themselves. In congruent trials, pricking and visual stimuli were applied to the same spatial location. In incongruent trials, pricking and visual stimuli were in the opposite spatial location. Participants were required to report on which location they felt a pricking sensation. Of primary interest was the effect of viewing another in pain upon vicarious pain errors, i.e., the number of trials in which an illusionary sensation was reported. Furthermore, we explored the effect of individual differences in hypervigilance to pain, dispositional empathy and the rubber hand illusion (RHI) upon vicarious pain errors. Results: Results of both experiments indicated that the number of vicarious pain errors was overall low. In line with expectations, the number of vicarious pain errors was higher in the pain responder group than in the comparison group. Self-reported hypervigilance for pain lowered the probability of reporting vicarious pain errors in the pain responder group, but dispositional empathy and the RHI did not. Conclusion: Our paradigm allows measuring vicarious pain experiences in students. However, the prevalence of vicarious experiences of pain is low, and only a small percentage of participants display the phenomenon. It remains however unknown which variables affect its occurrence. PMID:23781187

  11. Neuronal and immunological basis of action of antidepressants in chronic pain - clinical and experimental studies.

    PubMed

    Mika, Joanna; Zychowska, Magdalena; Makuch, Wioletta; Rojewska, Ewelina; Przewlocka, Barbara

    2013-01-01

    The current knowledge of the pharmacological actions of the tricyclic antidepressants (TCAs) has slowly evolved through their over 40-year history. Chronic pain represents one of the most important public health problems, and antidepressants are an essential part of the therapeutic strategy in addition to classical analgesics. This article reviews the available evidence on the efficacy and safety of antidepressants in chronic pain conditions; namely, headaches, low back pain, fibromyalgia, cancer pain and especially neuropathic pain. TCAs are traditionally the main type of depression medication used to treat chronic pain. Recently, new antidepressants were introduced into clinical use, with a significant reduction in side effects and equivalent efficacy on mood disorders. These new drugs that are effective for chronic pain belong to the tetracyclic antidepressants (TeCAs) group (amoxapine, maprotiline), the serotonin and noradrenaline reuptake inhibitors (SNRIs) group (duloxetine, venlafaxine, milnacipran) and the atypical antidepressants group (bupropion, trazodone, mirtazapine, nefazodone). In this review, we present the available publications on TCAs (amitriptyline, doxepin, imipramine, desipramine, nortriptyline), TeCAs (amoxapine, maprotiline), selective serotonin reuptake inhibitors (SSRIs) (citalopram, fluoxetine, paroxetine), SNRIs (duloxetine, venlafaxine, milnacipran) and atypical antidepressants (bupropion) for the treatment of neuropathic pain. We also review analgesics acting as both opioid receptor agonists and also acting as aminergic reuptake inhibitors. Existing data are insufficient to conclude which of these new classes of antidepressants has the best clinical profile and will be the most effective in the treatment of neuropathic pain; in addition, a lower incidence of side effects should be considered. Increased experimental and translational research is a key for further improvement of the treatment of chronic pain with antidepressants. However

  12. Does experimental low back pain change posteroanterior lumbar spinal stiffness and trunk muscle activity? A randomized crossover study.

    PubMed

    Wong, Arnold Y L; Parent, Eric C; Prasad, Narasimha; Huang, Christopher; Chan, K Ming; Kawchuk, Gregory N

    2016-05-01

    While some patients with low back pain demonstrate increased spinal stiffness that decreases as pain subsides, this observation is inconsistent. Currently, the relation between spinal stiffness and low back pain remains unclear. This study aimed to investigate the effects of experimental low back pain on temporal changes in posteroanterior spinal stiffness and concurrent trunk muscle activity. In separate sessions five days apart, nine asymptomatic participants received equal volume injections of hypertonic or isotonic saline in random order into the L3-L5 interspinous ligaments. Pain intensity, spinal stiffness (global and terminal stiffness) at the L3 level, and the surface electromyographic activity of six trunk muscles were measured before, immediately after, and 25-minute after injections. These outcome measures under different saline conditions were compared by generalized estimating equations. Compared to isotonic saline injections, hypertonic saline injections evoked significantly higher pain intensity (mean difference: 5.7/10), higher global (mean difference: 0.73N/mm) and terminal stiffness (mean difference: 0.58N/mm), and increased activity of four trunk muscles during indentation (P<0.05). Both spinal stiffness and trunk muscle activity returned to baseline levels as pain subsided. While previous clinical research reported inconsistent findings regarding the association between spinal stiffness and low back pain, our study revealed that experimental pain caused temporary increases in spinal stiffness and concurrent trunk muscle co-contraction during indentation, which helps explain the temporal relation between spinal stiffness and low back pain observed in some clinical studies. Our results substantiate the role of spinal stiffness assessments in monitoring back pain progression. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Experimental manipulations of pain catastrophizing influence pain levels in patients with chronic pain and healthy volunteers.

    PubMed

    Kjøgx, Heidi; Kasch, Helge; Zachariae, Robert; Svensson, Peter; Jensen, Troels S; Vase, Lene

    2016-06-01

    Pain catastrophizing (PC) has been related to pain levels in both patients experiencing acute or chronic pain and in healthy volunteers exposed to experimental pain. Still, it is unclear whether high levels of pain catastrophizing lead to high levels of pain or vice versa. We therefore tested whether levels of pain catastrophizing could be increased and decreased in the same participant through hypnotic suggestions and whether the altered level of situation-specific pain catastrophizing was related to increased and decreased pain levels, respectively. Using the spontaneous pain of 22 patients with chronic tension-type headache and experimentally induced pain in 22 healthy volunteers, participants were tested in 3 randomized sessions where they received 3 types of hypnotic suggestions: Negative (based on the 13 items in the Pain Catastrophizing Scale), Positive (coping-oriented reversion of the Pain Catastrophizing Scale), and Neutral (neutral sentence) hypnotic suggestions. The hypnotic suggestions significantly increased and decreased situation-specific PC in both patients and healthy volunteers (P < 0.001). Also, the levels of pain intensity and pain unpleasantness were significantly altered in both patients and healthy volunteers (P < 0.001). Furthermore, regression analyses showed that changes in pain catastrophizing predicted changes in pain in patients (R = 0.204-0.304; P < 0.045) and in healthy volunteers (R = 0.328-0.252; P < 0.018). This is the first study to successfully manipulate PC in positive and negative directions in both patients with chronic pain and healthy volunteers and to show that these manipulations significantly influence pain levels. These findings may have important theoretical and clinical implications.

  14. Reduced habituation to experimental pain in migraine patients: a CO(2) laser evoked potential study.

    PubMed

    Valeriani, M; de Tommaso, M; Restuccia, D; Le Pera, D; Guido, M; Iannetti, G D; Libro, G; Truini, A; Di Trapani, G; Puca, F; Tonali, P; Cruccu, G

    2003-09-01

    The habituation to sensory stimuli of different modalities is reduced in migraine patients. However, the habituation to pain has never been evaluated. Our aim was to assess the nociceptive pathway function and the habituation to experimental pain in patients with migraine. Scalp potentials were evoked by CO(2) laser stimulation (laser evoked potentials, LEPs) of the hand and facial skin in 24 patients with migraine without aura (MO), 19 patients with chronic tension-type headache (CTTH), and 28 control subjects (CS). The habituation was studied by measuring the changes of LEP amplitudes across three consecutive repetitions of 30 trials each (the repetitions lasted 5 min and were separated by 5-min intervals). The slope of the regression line between LEP amplitude and number of repetitions was taken as an index of habituation. The LEPs consisted of middle-latency, low-amplitude responses (N1, contralateral temporal region, and P1, frontal region) followed by a late, high-amplitude, negative-positive complex (N2/P2, vertex). The latency and amplitude of these responses were similar in both patients and controls. While CS and CTTH patients showed a significant habituation of the N2/P2 response, in MO patients this LEP component did not develop any habituation at all after face stimulation and showed a significantly lower habituation than in CS after hand stimulation. The habituation index of the vertex N2/P2 complex exceeded the normal limits in 13 out of the 24 MO patients and in none of the 19 CTTH patients (P<0.0001; Fisher's exact test). Moreover, while the N1-P1 amplitude showed a significant habituation in CS after hand stimulation, it did not change across repetitions in MO patients. In conclusion, no functional impairment of the nociceptive pathways, including the trigeminal pathways, was found in either MO or CTTH patients. But patients with migraine had a reduced habituation, which probably reflects an abnormal excitability of the cortical areas involved in

  15. The effect of Reiki on pain and anxiety in women with abdominal hysterectomies: a quasi-experimental pilot study.

    PubMed

    Vitale, Anne T; O'Connor, Priscilla C

    2006-01-01

    The purpose of this pilot study was to compare reports of pain and levels of state anxiety in 2 groups of women after abdominal hysterectomy. A quasi-experimental design was used in which the experimental group (n = 10) received traditional nursing care plus three 30-minute sessions of Reiki, while the control group (n = 12) received traditional nursing care. The results indicated that the experimental group reported less pain and requested fewer analgesics than the control group. Also, the experimental group reported less state anxiety than the control group on discharge at 72 hours postoperation. The authors recommend replication of this study with a similar population, such as women who require nonemergency cesarian section deliveries.

  16. Brain Network Response to Acupuncture Stimuli in Experimental Acute Low Back Pain: An fMRI Study.

    PubMed

    Shi, Yu; Liu, Ziping; Zhang, Shanshan; Li, Qiang; Guo, Shigui; Yang, Jiangming; Wu, Wen

    2015-01-01

    Most neuroimaging studies have demonstrated that acupuncture can significantly modulate brain activation patterns in healthy subjects, while only a few studies have examined clinical pain. In the current study, we combined an experimental acute low back pain (ALBP) model and functional magnetic resonance imaging (fMRI) to explore the neural mechanisms of acupuncture analgesia. All ALBP subjects first underwent two resting state fMRI scans at baseline and during a painful episode and then underwent two additional fMRI scans, once during acupuncture stimulation (ACUP) and once during tactile stimulation (SHAM) pseudorandomly, at the BL40 acupoint. Our results showed that, compared with the baseline, the pain state had higher regional homogeneity (ReHo) values in the pain matrix, limbic system, and default mode network (DMN) and lower ReHo values in frontal gyrus and temporal gyrus; compared with the OFF status, ACUP yielded broad deactivation in subjects, including nearly all of the limbic system, pain status, and DMN, and also evoked numerous activations in the attentional and somatosensory systems; compared with SHAM, we found that ACUP induced more deactivations and fewer activations in the subjects. Multiple brain networks play crucial roles in acupuncture analgesia, suggesting that ACUP exceeds a somatosensory-guided mind-body therapy for ALBP.

  17. A New Method for Sham-Controlled Acupuncture in Experimental Visceral Pain - a Randomized, Single-Blinded Study.

    PubMed

    Juel, Jacob; Liguori, Stefano; Liguori, Aldo; Valeriani, Massimiliano; Graversen, Carina; Olesen, Søren S; Drewes, Asbjørn M

    2016-07-01

    Acupuncture is increasingly used as an alternative to medical therapy for various pain conditions. To study the effect of acupuncture in experimental and clinical studies, a control condition with sham acupuncture is needed. However, as such models have not been established in assessment of acupunctures effect against visceral pain, this study aimed to validate a new method for blinded sham acupuncture in experimental rectal pain. Fifteen subjects underwent a sequence of either sham or real acupuncture in randomized order. In the sham arm, a hollow inner tube with a sharp tip was fitted into an outer tube and subjects were blinded to the stimulations. Before and after the intervention, pain was induced by rectal stimulation with an inflatable balloon distended until the subjects' pain threshold was reached. The resting electroencephalogram (EEG) was quantified by spectral power analysis to explore the central nervous system effects objectively. Additionally, after the second study day, the subject was asked to indicate the sequence of interventions. A significant increase in rectal balloon volume was observed after sham 12 ± 21 mL (P = 0.049) and acupuncture 17 ± 30 mL (P = 0.046). However, the change in volume was not different between groups (P = 0.6). No differences in EEG spectral power distributions between sham and acupuncture were seen (all P > 0.6). The correct sequence of sham and acupuncture was indicated by 36% of the subjects (P = 0.4). The presented sham procedure provides a valid method for blinding of "sham acupuncture" and may be used in future blinded controlled trials of acupuncture for visceral pain. © 2015 World Institute of Pain.

  18. Immediate effects of spinal manipulation on thermal pain sensitivity: an experimental study.

    PubMed

    George, Steven Z; Bishop, Mark D; Bialosky, Joel E; Zeppieri, Giorgio; Robinson, Michael E

    2006-08-15

    The underlying causes of spinal manipulation hypoalgesia are largely unknown. The beneficial clinical effects were originally theorized to be due to biomechanical changes, but recent research has suggested spinal manipulation may have a direct neurophysiological effect on pain perception through dorsal horn inhibition. This study added to this literature by investigating whether spinal manipulation hypoalgesia was: a) local to anatomical areas innervated by the lumbar spine; b) correlated with psychological variables; c) greater than hypoalgesia from physical activity; and d) different for A-delta and C-fiber mediated pain perception. Asymptomatic subjects (n = 60) completed baseline psychological questionnaires and underwent thermal quantitative sensory testing for A-delta and C-fiber mediated pain perception. Subjects were then randomized to ride a stationary bicycle, perform lumbar extension exercise, or receive spinal manipulation. Quantitative sensory testing was repeated 5 minutes after the intervention period. Data were analyzed with repeated measures ANOVA and post-hoc testing was performed with Bonferroni correction, as appropriate. Subjects in the three intervention groups did not differ on baseline characteristics. Hypoalgesia from spinal manipulation was observed in lumbar innervated areas, but not control (cervical innervated) areas. Hypoalgesic response was not strongly correlated with psychological variables. Spinal manipulation hypoalgesia for A-delta fiber mediated pain perception did not differ from stationary bicycle and lumbar extension (p > 0.05). Spinal manipulation hypoalgesia for C-fiber mediated pain perception was greater than stationary bicycle riding (p = 0.040), but not for lumbar extension (p = 0.105). Local dorsal horn mediated inhibition of C-fiber input is a potential hypoalgesic mechanism of spinal manipulation for asymptomatic subjects, but further study is required to replicate this finding in subjects with low back pain.

  19. Emotional modulation of experimental pain: a source imaging study of laser evoked potentials

    PubMed Central

    Stancak, Andrej; Fallon, Nicholas

    2013-01-01

    Negative emotions have been shown to augment experimental pain. As induced emotions alter brain activity, it is not clear whether pain augmentation during noxious stimulation would be related to neural activation existing prior to onset of a noxious stimulus or alternatively, whether emotional stimuli would only alter neural activity during the period of nociceptive processing. We analyzed the spatio-temporal patterns of laser evoked potentials (LEPs) occurring prior to and during the period of cortical processing of noxious laser stimuli during passive viewing of negative, positive, or neutral emotional pictures. Independent component analysis (ICA) was applied to series of source activation volumes, reconstructed using local autoregressive average model (LAURA). Pain was the strongest when laser stimuli were associated with negative emotional pictures. Prior to laser stimulus and during the first 100 ms after onset of laser stimulus, activations were seen in the left and right medial temporal cortex, cerebellum, posterior cingulate, and rostral cingulate/prefrontal cortex. In all these regions, positive or neutral pictures showed stronger activations than negative pictures. During laser stimulation, activations in the right and left anterior insula, temporal cortex and right anterior and posterior parietal cortex were stronger during negative than neutral or positive emotional pictures. Results suggest that negative emotional stimuli increase activation in the left and right anterior insula and temporal cortex, and right posterior and anterior parietal cortex only during the period of nociceptive processing. The role of background brain activation in emotional modulation of pain appears to be only permissive, and consisting in attenuation of activation in structures maintaining the resting state of the brain. PMID:24062659

  20. [A clinical and experimental study of the role of long-lasting perioperative epidural anesthesia in the prevention of phantom limb pain].

    PubMed

    Ovechkin, A M; Kukushkin, M L; Gnezdilov, A V; Reshetniak, V K

    1994-01-01

    The aim of this study was to investigate the possible onset of phantom limb pain (PLP) and its development depending on preoperative limb pain and type of anesthesia during limb amputation. It was experimentally proved that preliminary local anesthesia of rat sciatic nerve slowed down the development of pain syndrome after the operation as well as reduced the number of rats with pain syndrome, as compared to the group subjected to preliminary painful electrical stimulation of the operated on limb. The clinical data presented reveal a significant reduction in the incidence of PLP after perioperative epidural anesthesia, as compared to patients with preoperative pain operated on under general anesthesia.

  1. The association between dry needling-induced twitch response and change in pain and muscle function in patients with low back pain: a quasi-experimental study.

    PubMed

    Koppenhaver, Shane L; Walker, Michael J; Rettig, Charles; Davis, Joel; Nelson, Chenae; Su, Jonathan; Fernández-de-Las-Peñas, Cesar; Hebert, Jeffrey J

    2017-06-01

    To investigate the relationship between dry needling-induced twitch response and change in pain, disability, nociceptive sensitivity, and lumbar multifidus muscle function, in patients with low back pain (LBP). Quasi-experimental study. Department of Defense Academic Institution. Sixty-six patients with mechanical LBP (38 men, 28 women, age: 41.3 [9.2] years). Dry needling treatment to the lumbar multifidus muscles between L3 and L5 bilaterally. Examination procedures included numeric pain rating, the Modified Oswestry Disability Index, pressure algometry, and real-time ultrasound imaging assessment of lumbar multifidus muscle function before and after dry needling treatment. Pain pressure threshold (PPT) was used to measure nocioceptive sensitivity. The percent change in muscle thickness from rest to contraction was calculated to represent muscle function. Participants were dichotomized and compared based on whether or not they experienced at least one twitch response on the most painful side and spinal level during dry needling. Participants experiencing local twitch response during dry needling exhibited greater immediate improvement in lumbar multifidus muscle function than participants who did not experience a twitch (thickness change with twitch: 12.4 [6]%, thickness change without twitch: 5.7 [11]%, mean difference adjusted for baseline value, 95%CI: 4.4 [1 to 8]%). However, this difference was not present after 1-week, and there were no between-groups differences in disability, pain intensity, or nociceptive sensitivity. The twitch response during dry needling might be clinically relevant, but should not be considered necessary for successful treatment. Published by Elsevier Ltd.

  2. Reduced pressure pain thresholds in response to exercise in chronic fatigue syndrome but not in chronic low back pain: an experimental study.

    PubMed

    Meeus, Mira; Roussel, Nathalie A; Truijen, Steven; Nijs, Jo

    2010-10-01

    The aims of this study were to examine: (i) baseline pressure pain thresholds in patients with chronic fatigue syndrome and those with chronic low back pain compared with healthy subjects; (ii) the change in mean pain threshold in response to exercise; and (iii) associations with exercise-induced increase in nitric oxide. Twenty-six patients with chronic fatigue syndrome suffering of chronic pain, 21 patients with chronic low back pain and 31 healthy subjects. Participants underwent a submaximal aerobic exercise protocol on a bicycle ergometer, preceded and followed by venous blood sampling (nitric oxide) and algometry (hand, arm, calf, low back). Patients with chronic fatigue syndrome presented overall lower pain thresholds compared with healthy subjects and patients with chronic low back pain (p < 0.05). No significant differences were found between healthy subjects and patients with chronic low back pain. After submaximal aerobic exercise, mean pain thresholds decreased in patients with chronic fatigue syndrome, and increased in the others (p < 0.01). At baseline, nitric oxide levels were significantly higher in the chronic low back pain group. After controlling for body mass index, no significant differences were seen between the groups at baseline or in response to exercise. Nitric oxide was not related to pain thresholds in either group. The results suggest hyperalgesia and abnormal central pain processing during submaximal aerobic exercise in chronic fatigue syndrome, but not in chronic low back pain. Nitric oxide appeared to be unrelated to pain processing.

  3. The effect of experimental low back pain on lumbar muscle activity in people with a history of clinical low back pain: a muscle functional MRI study.

    PubMed

    Danneels, Lieven; Cagnie, Barbara; D'hooge, Roseline; De Deene, Yves; Crombez, Geert; Vanderstraeten, Guy; Parlevliet, Thierry; Van Oosterwijck, Jessica

    2016-02-01

    In people with a history of low back pain (LBP), structural and functional alterations have been observed at several peripheral and central levels of the sensorimotor pathway. These existing alterations might interact with the way the sensorimotor system responds to pain. We examined this assumption by evaluating the lumbar motor responses to experimental nociceptive input of 15 participants during remission of unilateral recurrent LBP. Quantitative T2 images (muscle functional MRI) were taken bilaterally of multifidus, erector spinae, and psoas at several segmental levels (L3 upper and L4 upper and lower endplate) and during several conditions: 1) at rest, 2) upon trunk-extension exercise without pain, and 3) upon trunk-extension exercise with experimental induced pain at the clinical pain-side (1.5-ml intramuscular hypertonic saline injections in erector spinae). Following experimental pain induction, muscle activity levels similarly reduced for all three muscles, on both painful and nonpainful sides, and at multiple segmental levels (P = 0.038). Pain intensity and localization from experimental LBP were similar as during recalled clinical LBP episodes. In conclusion, unilateral and unisegmental experimental LBP exerts a generalized and widespread decrease in lumbar muscle activity during remission of recurrent LBP. This muscle response is consistent with previous observed patterns in healthy people subjected to the same experimental pain paradigm. It is striking that similar inhibitory patterns in response to pain could be observed, despite the presence of preexisting alterations in the lumbar musculature during remission of recurrent LBP. These results suggest that motor output can modify along the course of recurrent LBP. Copyright © 2016 the American Physiological Society.

  4. Neuromechanical responses after biofeedback training in participants with chronic low back pain: an experimental cohort study.

    PubMed

    Pagé, Isabelle; Marchand, Andrée-Anne; Nougarou, François; O'Shaughnessy, Julie; Descarreaux, Martin

    2015-09-01

    The objective of this study was to evaluate changes in neuromechanical responses and clinical outcomes in chronic low back pain participants after 4 sessions of biofeedback training. Twenty-one participants took part in an electromyography biofeedback 4-session training program aimed at reducing lumbar paraspinal muscle activity during full trunk flexion. The sessions consisted of ~46 trunk flexion-extension divided into 5 blocks. The effects of training blocks and sessions on lumbar flexion-relaxation ratio and lumbopelvic ranges of motion were assessed. Changes in disability (Oswestry Disability Index), pain intensity (numerical rating scale), and fear of movement (Tampa Scale for Kinesiophobia) were also evaluated. Analyses of variance revealed a significant block effect for which an increase in the flexion-relaxation ratio and the lumbar range of motion between block 1 and the other blocks for sessions 1 and 2 (P < .0001) was observed. However, no significant session or interaction effect was observed. Among clinical outcomes, only fear of movement significantly decreased between the baseline (mean [SD], 33.05 [7.18]) and the fourth session (29.80 [9.88]) (P = .02). There was no significant correlation between clinical outcomes and neuromechanical variables. Biofeedback training led to decreases in lumbar paraspinal muscle activity in full trunk flexion and increases in lumbopelvic range of motion in participants with chronic nonspecific low back pain. Although the neuromechanical changes were mostly observed at the early stage of the program, the presence of a decrease in the fear of movement suggests that the participants' initially limited ROMs may have been modulated by fear avoidance behaviors. Copyright © 2015 National University of Health Sciences. Published by Elsevier Inc. All rights reserved.

  5. Effects of acupressure on menstrual distress and low back pain in dysmenorrheic young adult women: an experimental study.

    PubMed

    Chen, Huei-Mein; Wang, Hsiu-Hung; Chiu, Min-Huei; Hu, Hsou-Mei

    2015-06-01

    The purpose of this study was to examine the effects of acupressure on menstrual distress and low back pain (LBP) in dysmenorrheic young adult women. In all, 129 female students, who had been experiencing dysmenorrhea with LBP during menstruation and who scored more than 4 points on the visual analog scale for pain, were randomly assigned to an experimental group and a control group. The experimental group (n = 65) received acupressure massage three times a week for 30 minutes on the sanyinjiao (SP6), ciliao (BL32), and taichong (Liver 3) acupoints. The control group (n = 64) received only a manual of menstrual health education without acupressure intervention. Data were collected at five time points: at baseline, 30 minutes, and 4, 8, and 12 months after the intervention. During the 12-month follow-up, the experimental group had significantly lower menstrual distress and LBP scores than the control group. Among 65 participants in the experimental group, 53 (82%) reported a moderate to high levels of menstrual distress, 51 (78%) reported moderate to high levels of LBP relief, and 49 (75%) reported moderate to high levels of satisfaction with acupressure. Our findings may serve as a reference for health care professionals and young women to improve self-care during menstruation and help further understand the therapeutic effects of acupressure on menstrual distress and LBP.

  6. Pain Intensity after an Ice Pack Application Prior to Venipuncture among School-Age Children: An Experimental Study

    ERIC Educational Resources Information Center

    Alalo, Fadeelah Mansour Ahmed; Ahmad, Awatef El Sayed; El Sayed, Hoda Mohamed Nafee

    2016-01-01

    Venipuncture and other invasive procedures as blood draws, intramuscular injections or heel pricks are the most commonly performed painful procedures in children. These can be a terrifying and painful experience for children and their families. The present study aimed to identify Pain intensity after an ice pack application prior to venipuncture…

  7. Increase of pain threshold as a function of conditionsing electrical stimulation. An experimental study with application to electro-acupuncture for pain suppression.

    PubMed

    Holmgren, E

    1975-04-01

    Previous studies have shown that 2 Hz electrical conditioning stimulation of hands and cheeks increased the tooth pain threshold. In the present study the relation between strength of conditioning stimulation and amplitude of pain threshold increase is elucidated. Intense conditioning stimulation, giving subjective beating sensations and extensive muscles twitches, is required to obtain a substantial pain threshold increase. The results are discussed in relation to intensities used in electro-acupuncture and to interindividual variation of the effect. It is suggested that pain relief is obtained due to an inhibitory feed-back mechanism activated, not via low threshold afferents but via high threshold afferents.

  8. Characteristics of response to experimental pain in sexually abused women.

    PubMed

    Granot, Michal; Somer, Eli; Zisman-Ilani, Yaara; Beny, Ahuva; Sadger, Ronit; Mirkin, Ronit; Moont, Ruth; Yovell, Yoram

    2011-09-01

    Women with a history of sexual abuse (SA) commonly report greater pain symptoms. It is still unclear whether enhanced pain susceptibility is the result of altered pain processing and response. Therefore, this pilot study aimed to explore pain sensitivity to experimentally induced pain and associated psychology in women with a history of severe SA. Twenty-one survivors of severe, long-lasting SA and 21 control women underwent experimentally induced heat pain and completed psychological questionnaires. Pain measures included heat pain thresholds, pain intensity ratings, and pain tolerance in response to contact heat, painful stimulation delivered to the volar forearm. Questionnaires included somatization (Brief Symptom Inventory), personality traits including harm avoidance, novelty seeking, and reward dependence (Cloninger tridimensional personality questionnaire), and levels of dissociation (Dissociative Experiences Scale). SA women had elevated heat pain thresholds (45.7±2.2°C vs. 43.9±3.1°C; P=0.042) and higher pain intensity ratings (on a 0 to 100 scale: 80.0±26.6 vs. 51.2±27.7; P=0.001). In addition, they had lower tolerability to painful tonic stimulation, greater somatization, and larger harm avoidance scores. Regression analyses showed that higher pain intensity ratings in SA women associated with greater tendency for harm avoidance but not with levels of dissociation. Women with a history of severe SA seem to have a paradoxical pattern of experimental pain response, characterized by both higher pain thresholds and increased pain intensity ratings. This pattern is associated with the personality trait of harm avoidance. Models that might account for these findings are discussed.

  9. Pain Intervention for people with Dementia in nursing homes (PID): study protocol for a quasi-experimental nurse intervention.

    PubMed

    Koppitz, Andrea; Bosshard, Georg; Blanc, Geneviève; Hediger, Hannele; Payne, Sheila; Volken, Thomas

    2017-04-21

    It is estimated that 19 to 83% of people with dementia suffer from pain that is inadequately treated in the last months of life. A large number of healthcare workers who care for these people in nursing homes lack appropriate expertise and may therefore not always recognise, assess and treat pain in those with dementia who have complex problems on time, properly and efficiently. The aim of this intervention trial is to identify care needs of people with dementia suffering from pain living in a nursing home. A quasi-experimental nurse-led intervention trial based on a convenience sample of four nursing homes in the Swiss Canton of Zurich examines the effects on dementia patients (n = 411), the healthcare institution and the qualification level of the healthcare workers compared to historical controls, using an event analysis and a multilevel analysis. Healthcare workers will be individually trained how to assess, intervene and evaluate acute and chronic pain. There are three data-monitoring cycles (T0, T1, T2) and two intervention cycles (I1, I2) with a total study duration of 425 days. There is also a process evaluation based on Dobbins analyses that analyse in particular the potentials for change in clinical practice of change agents. The aim of the intervention trial is to improve pain management strategies in older people with dementia in nursing homes. Clinically significant findings will be expected that will help reduce suffering in the sense of "total pain" for people with dementia. The joint intra- and interdisciplinary collaboration between practice and supply-oriented (nursing) research will have both a lasting effect on the efficiency measurement and provide scientifically sound results. Nursing homes can integrate the findings from the intervention trial into their internal quality control process. The potential for improvements can be directly influenced by the nursing home itself. Registration trial number: DRKS00009726 on DRKS, registered 10

  10. Pain-related emotions modulate experimental pain perception and autonomic responses.

    PubMed

    Rainville, Pierre; Bao, Quoc Viet Huynh; Chrétien, Pablo

    2005-12-05

    The effect of emotions on pain perception is generally recognized but the underlying mechanisms remain unclear. Here, emotions related to pain were induced in healthy volunteers using hypnosis, during 1-min immersions of the hand in painfully hot water. In Experiment 1, hypnotic suggestions were designed to induce various positive or negative emotions. Compared to a control condition with hypnotic-relaxation, negative emotions produced robust increases in pain. In Experiment 2, induction of pain-related anger and sadness were found to increase pain. Pain increases were associated with increases in self-rated desire for relief and decreases in expectation of relief, and with increases in arousal, negative affective valence and decreases in perceived control. In Experiment 3, hypnotic suggestions specifically designed to increase and decrease the desire for relief produced increases and decreases in pain, respectively. In all three experiments, emotion-induced changes in pain were most consistently found on ratings of pain unpleasantness compared to pain intensity. Changes in pain-evoked cardiac responses (R-R interval decrease), measured in experiments 2 and 3, were consistent with changes in pain unpleasantness. Correlation and multiple regression analyses suggest that negative emotions and desire for relief influence primarily pain affect and that pain-evoked autonomic responses are strongly associated with pain affect. These results confirm the hypothesized influence of the desire for relief on pain perception, and particularly on pain affect, and support the functional relation between pain affect and autonomic nociceptive responses. This study provides further experimental confirmation that pain-related emotions influence pain perception and pain-related physiological responses.

  11. Psychophysical outcomes from a randomized pilot study of manual, electro, and sham acupuncture treatment on experimentally induced thermal pain.

    PubMed

    Kong, Jian; Fufa, Duretti T; Gerber, Andrew J; Rosman, Ilana S; Vangel, Mark G; Gracely, Richard H; Gollub, Randy L

    2005-01-01

    In this pilot study comparing the analgesic effects of three acupuncture modes--manual, electro, and placebo (with Streitberger placebo needles)--in a cohort of healthy subjects, we found that verum acupuncture treatment, but not placebo, lowered pain ratings in response to calibrated noxious thermal stimuli. This finding was mainly the result of highly significant analgesia in 5 of the 11 subjects who completed the 5-session study. Of the 5 responders, 2 responded only to electroacupuncture and 3 only to manual acupuncture, suggesting that acupuncture's analgesic effects on experimental pain may be dependent on both subject and mode. We developed a simple quantitative assessment tool, the Subjective Acupuncture Sensation Scale (SASS), comprised of 9 descriptors and an anxiety measure to study the relationship between the deqi sensation induced by acupuncture and the putative therapeutic effects of acupuncture. The SASS results confirm that the deqi sensation is complex, with all subjects rating multiple descriptors during each mode. We found significant correlations of analgesia with SASS ratings of numbness and soreness, but not with ratings of stabbing, throbbing, tingling, burning, heaviness, fullness, or aching. This suggests that attributes of the deqi sensation may be useful clinical indicators of effective treatment. The results of this study indicate the existence of both individual subject and acupuncture mode variability in the analgesic effects of acupuncture. This suggests that switching acupuncture mode may be a treatment option for unresponsive patients.

  12. Associations between psychological variables and pain in experimental pain models. A systematic review.

    PubMed

    Hansen, M S; Horjales-Araujo, E; Dahl, J B

    2015-10-01

    The association between pain and psychological characteristics has been widely debated. Thus, it remains unclear whether an individual's psychological profile influences a particular pain experience, or if previous pain experience contributes to a certain psychological profile. Translational studies performed in healthy volunteers may provide knowledge concerning psychological factors in healthy individuals as well as basic pain physiology. The aim of this review was to investigate whether psychological vulnerability or specific psychological variables in healthy volunteers are predictive of the level of pain following experimental pain models. A systematic search on the databases, PubMed, Embase, Cochcrane library, and Clinicaltrials.gov was performed during September 2014. All trials investigating the association between psychological variables and experimental pain in healthy volunteers were considered for inclusion. Twenty-nine trials met the inclusion criteria, with a total of 2637 healthy volunteers. The included trials investigated a total of 45 different psychological tests and 27 different types of pain models. The retrieved trials did not present a sufficiently homogenous group to perform meta-analysis. The collected results were diverse. A total of 16 trials suggested that psychological factors may predict the level of pain, seven studies found divergent results, and six studies found no significant association between psychological variables and experimental pain. Psychological factors may have predictive value when investigating experimental pain. However, due to substantial heterogeneity and methodological shortcomings of the published literature, firm conclusions are not possible. © 2015 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  13. Meta-analysis on brain representation of experimental dental pain.

    PubMed

    Lin, C-S; Niddam, D M; Hsu, M-L

    2014-02-01

    Functional magnetic resonance imaging (fMRI) has been widely used for investigating the brain representation associated with dental pain evoked by pulpal electrical stimulation. However, because of the heterogeneity of experimental designs and the small sample size of individual studies, the common brain representation regarding dental pain has remained elusive. We used imaging meta-analysis to investigate six dental pain-related fMRI studies (n = 87) and tested 3 hypotheses: (1) Dental pain is associated with the 'core' pain-related network; (2) pain-related brain activation is somatotopically organized in the somatosensory cortex; and (3) dental pain is associated with the cognitive-affective network related to pain. Qualitative and quantitative meta-analyses revealed: (1) common activation of the core pain-related network, including the somatosensory cortex, the insula, and the cingulate cortex; (2) inconsistency in somatotopically organized activation of the primary somatosensory cortex; and (3) common activation in the dorsolateral prefrontal cortex, suggesting a role of re-appraisal and coping in the experience of dental pain. In conclusion, fMRI combined with pulpal stimulation can effectively evoke activity in the pain-related network. The dental pain-related brain representation disclosed the mechanisms of how sensory and cognitive-affective factors shape dental pain, which will help in the development of more effective customized methods for central pain control.

  14. Experimental integrative muscular movement technique enhances cervical range of motion in patients with chronic neck pain: a pilot study.

    PubMed

    Rohe, Benjamin G; Carter, Ronald; Thompson, William R; Duncan, Randall L; Cooper, Carlton R

    2015-04-01

    Neck pain presents a tremendous physical and financial burden. This study compared the efficacy of the complementary and alternative medical treatments of integrative muscular movement technique (IMMT) and Swedish massage on neck pain in women of occupation age, the largest demographic group with neck pain. A total of 38 women were assigned to IMMT (n=28) or Swedish massage (n=10) in a blinded manner. Both groups received eight 30-minute treatments over 4 weeks. Cervical range of motion (ROM) in flexion, extension, sidebending, and rotation was measured before and after treatment. Each patient's pain was assessed by using an analogue pain scale of 0-10. Compared with the Swedish massage group, patients receiving IMMT experienced a significant increase in ROM in cervical flexion (p<0.001), extension (p<0.001), sidebending (p<0.05), and rotation (p<0.001). Absolute change in pain for IMMT was -1.75 units compared with -0.3 units for Swedish massage (p<0.05). Patients receiving the IMMT demonstrated significantly improved cervical ROM in every movement measured compared with Swedish massage. Inclusion of the IMMT in a treatment regimen for chronic neck pain may lead to decreased pain and increased cervical ROM. These positive effects of the IMMT intervention may have a role in enhancing functional outcomes in patients with neck pain.

  15. Experimental pain ratings and reactivity of cortisol and soluble tumor necrosis factor-α receptor II following a trial of hypnosis: Results of a randomized controlled pilot study

    PubMed Central

    Goodin, Burel R.; Quinn, Noel B.; Kronfli, Tarek; King, Christopher D.; Page, Gayle G.; Haythornthwaite, Jennifer A.; Edwards, Robert R.; Stapleton, Laura M.; McGuire, Lynanne

    2011-01-01

    Objective Current evidence supports the efficacy of hypnosis for reducing the pain associated with experimental stimulation and various acute and chronic conditions; however, the mechanisms explaining how hypnosis exerts its effects remain less clear. The hypothalamic-pituitary-adrenal (HPA) axis and pro-inflammatory cytokines represent potential targets for investigation given their purported roles in the perpetuation of painful conditions; yet, no clinical trials have thus far examined the influence of hypnosis on these mechanisms. Design Healthy participants, highly susceptible to the effects of hypnosis, were randomized to either a hypnosis intervention or a no-intervention control. Using a cold pressor task, assessments of pain intensity and pain unpleasantness were collected prior to the intervention (Pre) and following the intervention (Post) along with pain-provoked changes in salivary cortisol and the soluble receptor of tumor necrosis factor-α (sTNFαRII). Results Compared to the no-intervention control, data analyses revealed that hypnosis significantly reduced pain intensity and pain unpleasantness. Hypnosis was not significantly associated with suppression of cortisol or sTNFαRII reactivity to acute pain from Pre to Post; however, the effect sizes for these associations were medium-sized. Conclusions Overall, the findings from this randomized controlled pilot study support the importance of a future large-scale study on the effects of hypnosis for modulating pain-related changes of the HPA axis and pro-inflammatory cytokines. PMID:22233394

  16. Experimental pain ratings and reactivity of cortisol and soluble tumor necrosis factor-α receptor II following a trial of hypnosis: results of a randomized controlled pilot study.

    PubMed

    Goodin, Burel R; Quinn, Noel B; Kronfli, Tarek; King, Christopher D; Page, Gayle G; Haythornthwaite, Jennifer A; Edwards, Robert R; Stapleton, Laura M; McGuire, Lynanne

    2012-01-01

    Current evidence supports the efficacy of hypnosis for reducing the pain associated with experimental stimulation and various acute and chronic conditions; however, the mechanisms explaining how hypnosis exerts its effects remain less clear. The hypothalamic-pituitary-adrenal (HPA) axis and pro-inflammatory cytokines represent potential targets for investigation given their purported roles in the perpetuation of painful conditions; yet, no clinical trials have thus far examined the influence of hypnosis on these mechanisms. Healthy participants, highly susceptible to the effects of hypnosis, were randomized to either a hypnosis intervention or a no-intervention control. Using a cold pressor task, assessments of pain intensity and pain unpleasantness were collected prior to the intervention (Pre) and following the intervention (Post) along with pain-provoked changes in salivary cortisol and the soluble tumor necrosis factor-α receptor II (sTNFαRII). Compared with the no-intervention control, data analyses revealed that hypnosis significantly reduced pain intensity and pain unpleasantness. Hypnosis was not significantly associated with suppression of cortisol or sTNFαRII reactivity to acute pain from Pre to Post; however, the effect sizes for these associations were medium-sized. Overall, the findings from this randomized controlled pilot study support the importance of a future large-scale study on the effects of hypnosis for modulating pain-related changes of the HPA axis and pro-inflammatory cytokines. Wiley Periodicals, Inc.

  17. Evaluation of Anti-Hyperalgesic and Analgesic Effects of Two Benzodiazepines in Human Experimental Pain: A Randomized Placebo-Controlled Study

    PubMed Central

    Vuilleumier, Pascal H.; Besson, Marie; Desmeules, Jules; Arendt-Nielsen, Lars; Curatolo, Michele

    2013-01-01

    Background and Aims Compounds that act on GABA-receptors produce anti-hyperalgesia in animal models, but little is known on their effects in humans. The aim of this study was to explore the potential usefulness of GABA-agonism for the control of pain in humans. Two agonists at the benzodiazepine-binding site of GABAA-receptors (clobazam and clonazepam) were studied using multiple experimental pain tests. Positive results would support further investigation of GABA agonism for the control of clinical pain. Methods In a randomized double-blind crossover design, 16 healthy male volunteers received clobazam 20 mg, clonazepam 1 mg and tolterodine 1 mg (active placebo). The area of static hyperalgesia after intradermal capsaicin injection was the primary endpoint. Secondary endpoints were: area of dynamic hyperalgesia, response to von Frey hair stimulation, pressure pain thresholds, conditioned pain modulation, cutaneous and intramuscular electrical pain thresholds (1, 5 and 20 repeated stimulation), and pain during cuff algometry. Results For the primary endpoint, an increase in the area of static hyperalgesia was observed after administration of placebo (p<0.001), but not after clobazam and clonazepam. Results suggestive for an anti-hyperalgesic effect of the benzodiazepines were obtained with all three intramuscular pain models and with cuff algometry. No effect could be detected with the other pain models employed. Conclusions Collectively, the results are suggestive for a possible anti-hyperalgesic effect of drugs acting at the GABAA-receptors in humans, particularly in models of secondary hyperalgesia and deep pain. The findings are not conclusive, but support further clinical research on pain modulation by GABAergic drugs. Because of the partial results, future research should focus on compounds acting selectively on subunits of the GABA complex, which may allow the achievement of higher receptor occupancy than unselective drugs. Our data also provide information

  18. A theory-based educational intervention targeting nurses' attitudes and knowledge concerning cancer-related pain management: a study protocol of a quasi-experimental design.

    PubMed

    Borglin, Gunilla; Gustafsson, Markus; Krona, Hans

    2011-09-23

    Pain is one of the most frequent problems among patients diagnosed with cancer. Despite the availability of effective pharmacological treatments, this group of patients often receives less than optimal treatment. Research into nurses' pain management highlights certain factors, such as lack of knowledge and attitudes and inadequate procedures for systematic pain assessment, as common barriers to effective pain management. However, educational interventions targeting nurses' pain management have shown promise. As cancer-related pain is also known to have a negative effect on vital aspects of the patient's life, as well as being commonly associated with problems such as sleep, fatigue, depression and anxiety, further development of knowledge within this area is warranted. A quasi-experimental study design will be used to investigate whether the implementation of guidelines for systematic daily pain assessments following a theory-based educational intervention will result in an improvement in knowledge and attitude among nurses. A further aim is to investigate whether the intervention that targets nurses' behaviour will improve hospital patients' perception of pain. Data regarding nurses' knowledge and attitudes to pain (primary outcome), patient perception regarding pain (secondary outcome), together with socio-demographic variables, will be collected at baseline and at four weeks and 12 weeks following the intervention. Nursing care is nowadays acknowledged as an increasingly complicated activity and "nursing complexity is such that it can be seen as the quintessential complex intervention." To be able to change and improve clinical practice thus requires multiple points of attack appropriate to meet complex challenges. Consequently, we expect the theory-based intervention used in our quasi-experimental study to improve care as well as quality of life for this group of patients and we also envisage that evidence-based guidelines targeting this patient group's pain

  19. Spontaneous Chronic Pain After Experimental Thoracotomy Revealed by Conditioned Place Preference: Morphine Differentiates Tactile Evoked Pain From Spontaneous Pain.

    PubMed

    Hung, Ching-Hsia; Wang, Jeffrey Chi-Fei; Strichartz, Gary R

    2015-09-01

    Chronic pain after surgery limits social activity, interferes with work, and causes emotional suffering. A major component of such pain is reported as resting or spontaneous pain with no apparent external stimulus. Although experimental animal models can simulate the stimulus-evoked chronic pain that occurs after surgery, there have been no studies of spontaneous chronic pain in such models. Here the conditioned place preference (CPP) paradigm was used to reveal resting pain after experimental thoracotomy. Male Sprague Dawley rats received a thoracotomy with 1-hour rib retraction, resulting in evoked tactile hypersensitivity, previously shown to last for at least 9 weeks. Intraperitoneal injections of morphine (2.5 mg/kg) or gabapentin (40 mg/kg) gave equivalent 2- to 3-hour-long relief of tactile hypersensitivity when tested 12 to 14 days postoperatively. In separate experiments, single trial CPP was conducted 1 week before thoracotomy and then 12 days (gabapentin) or 14 days (morphine) after surgery, followed the next day by 1 conditioning session with morphine or gabapentin, both versus saline. The gabapentin-conditioned but not the morphine-conditioned rats showed a significant preference for the analgesia-paired chamber, despite the equivalent effect of the 2 agents in relieving tactile allodynia. These results show that experimental thoracotomy in rats causes spontaneous pain and that some analgesics, such as morphine, that reduce evoked pain do not also relieve resting pain, suggesting that pathophysiological mechanisms differ between these 2 aspects of long-term postoperative pain. Perspective: Spontaneous pain, a hallmark of chronic postoperative pain, is demonstrated here in a rat model of experimental postthoracotomy pain, further validating the use of this model for the development of analgesics to treat such symptoms. Although stimulus-evoked pain was sensitive to systemic morphine, spontaneous pain was not, suggesting different mechanistic

  20. Amantadine sulfate reduces experimental sensitization and pain in chronic back pain patients.

    PubMed

    Kleinböhl, Dieter; Görtelmeyer, Roman; Bender, Hans-Joachim; Hölzl, Rupert

    2006-03-01

    We investigated if established psychophysical measures of enhanced experimental sensitization in chronic musculoskeletal pain can be reduced by adjuvant treatment with a N-methyl-d-aspartate receptor antagonist, amantadine sulfate, and whether a reduction in sensitization might be accompanied by a concurrent improvement in clinical pain. Sensitization was evaluated by an experimental tonic heat model of short-term sensitization with concurrent subjective and behavioral psychophysical scaling. Twenty-six patients with chronic back pain were included in the randomized, double-blind, placebo-controlled study and received daily dosages of either placebo or 100 mg of amantadine sulfate during a 1-wk treatment. Participants completed quantitative sensory testing of pain thresholds and experimental sensitization before and after treatment and clinical pain ratings before, during, and after treatment. Experimental sensitization and clinical pain were reduced in patients receiving verum. Initially, experimental sensitization was enhanced in patients, with early sensitization at nonpainful intensities of contact heat and enhanced sensitization at painful intensities, as shown previously. After 1 wk of treatment, experimental sensitization was reduced with amantadine sulfate but not with placebo. We conclude that adjuvant chronic pain treatment with N-methyl-d-aspartate receptor antagonists might be beneficial for chronic pain if enhanced sensitization is involved and that the quantitative sensory test of temporal summation may be used to verify this.

  1. The effect of the application of manual pressure before the administration of intramuscular injections on students' perceptions of postinjection pain: a semi-experimental study.

    PubMed

    Öztürk, Deniz; Baykara, Zehra Gocmen; Karadag, Ayise; Eyikara, Evrim

    2017-06-01

    To evaluate the efficacy of applying manual pressure before intramuscular injection and compare it with the standard injection technique in terms of reducing the young adult student's postinjection pain. The administration of intramuscular injections is a procedure performed by nurses and one that causes anxiety and pain for the patient. Nurses have ethical and legal obligations to mitigate injection-related pain and the nurses' use of effective pain management not only provides physical comfort to the patients, but also improves the patients' experience. Comparative experimental study. This study was conducted with first-year university students (n = 123) who were scheduled for hepatitis A and hepatitis B vaccination via deltoid muscle injection. Students were randomly assigned to the groups. Comparison group students (n = 60) were given an injection using the conventional method, that is without manual pressure being applied prior to the injection. The experimental group students (n = 63) received manual pressure at the vaccination site immediately before injection for a period of 10 seconds. The two techniques were used randomly. The subjects were given pressure to the injection site, and perceived pain intensity was measured using Numerical Rating Scale. Findings demonstrate that students experienced significantly less pain when they received injections with manual pressure compared with the standard injection technique. The postinjection average pain score in the comparison group was higher than that in the experimental group (p < 0·05). This study's results show that the application of manual pressure to the injection site before intramuscular injections reduces postinjection pain intensity in young adult students (p < 0·05). Based on these results before the injection, applying manual pressure to the adult's intramuscular injection site is recommended. Applying pressure to the injection area is a simple and cost-effective method to reduce the

  2. The pain inhibiting pain effect: an electrophysiological study in humans.

    PubMed

    Reinert, A; Treede, R; Bromm, B

    2000-04-17

    This study examines the counterirritation phenomenon of experimental pain in human subjects. Phasic pain induced by intracutaneous electrical stimuli was simultaneously applied with tonic pain induced by ischemic muscle work. Pain ratings, spontaneous EEG and evoked potentials were measured. We found a significant reduction of phasic pain ratings during and 10 min after tonic pain. The late somatosensory evoked potentials as neurophysiological correlates of phasic pain sensation were attenuated until 20 min after tonic pain offset. The extent of phasic pain relief due to concomitant tonic pain was small but significant, comparable to the effect of a regular systemic dose of a narco-analgesic drug in this experimental pain model. On the other hand, no modulations in the late components of the auditory evoked potential and the power spectrum of the spontaneous EEG were observed. These variables reflect the attention and vigilance of the subject and are well-known to be affected by opioids. The only exception was an increase of beta power, which might reflect hyperarousal during tonic pain. These results support the suggestion, that the analgesic effect of heterotopic noxious stimulation in humans is based on the activation of a specific inhibitory pain control system. Systemic release of endogenous opioids is unlikely to be involved, because the typical effects of opioids on the EEG were not observed.

  3. The influence of experimentally induced pain on shoulder muscle activity.

    PubMed

    Diederichsen, Louise Pyndt; Winther, Annika; Dyhre-Poulsen, Poul; Krogsgaard, Michael R; Nørregaard, Jesper

    2009-04-01

    Muscle function is altered in painful shoulder conditions. However, the influence of shoulder pain on muscle coordination of the shoulder has not been fully clarified. The aim of the present study was to examine the effect of experimentally induced shoulder pain on shoulder muscle function. Eleven healthy men (range 22-27 years), with no history of shoulder or cervical problems, were included in the study. Pain was induced by 5% hypertonic saline injections into the supraspinatus muscle or subacromially. Seated in a shoulder machine, subjects performed standardized concentric abduction (0 degrees -105 degrees) at a speed of approximately 120 degrees/s, controlled by a metronome. During abduction, electromyographic (EMG) activity was recorded by intramuscular wire electrodes inserted in two deeply located shoulder muscles and by surface-electrodes over six superficially located shoulder muscles. EMG was recorded before pain, during pain and after pain had subsided and pain intensity was continuously scored on a visual analog scale (VAS). During abduction, experimentally induced pain in the supraspinatus muscle caused a significant decrease in activity of the anterior deltoid, upper trapezius and the infraspinatus and an increase in activity of lower trapezius and latissimus dorsi muscles. Following subacromial injection a significantly increased muscle activity was seen in the lower trapezius, the serratus anterior and the latissimus dorsi muscles. In conclusion, this study shows that acute pain both subacromially and in the supraspinatus muscle modulates coordination of the shoulder muscles during voluntary movements. During painful conditions, an increased activity was detected in the antagonist (latissimus), which support the idea that localized pain affects muscle activation in a way that protects the painful structure. Further, the changes in muscle activity following subacromial pain induction tend to expand the subacromial space and thereby decrease the load

  4. Relevance of physical fitness levels and exercise-related beliefs for self-reported and experimental pain in fibromyalgia: an explorative study.

    PubMed

    de Bruijn, Saskia T; van Wijck, Albert J M; Geenen, Rinie; Snijders, Tom J; van der Meulen, Wout J T M; Jacobs, Johannes W G; Veldhuijzen, Dieuwke Swaantje

    2011-09-01

    It has been suggested that low physical fitness is a contributor to pain in fibromyalgia and that exercise-related beliefs play a role in the persistence of this association. Yet the association between physical fitness and pain is hardly explored in detail. The aim of this exploratory study in patients with fibromyalgia was to investigate the association of physical fitness levels with self-reported and experimental pain as well as with pain catastrophizing and activity-avoidance beliefs. Physical fitness of 18 patients with fibromyalgia was examined using maximal ergocycling and the 6-minute walking test (6MWT). Pain intensity was assessed using self-report scales and quantitative sensory testing. A reduced walking distance on the 6MWT was correlated with more severe self-reported pain on the Fibromyalgia Impact Questionnaire (r = -0.52, P < 0.05). Recovery of heart rate after ergocycling was correlated with cold pain thresholds (r = 0.70, P < 0.01), pressure pain thresholds (r = -0.70, P < 0.01), and heat wind-up (r = 0.66, P < 0.05). Activity-avoidance beliefs correlated with a lower peak VO2 on the cycle test (r = -0.52, P < 0.05), a shorter distance on the 6MWT (r = -0.56, P < 0.05), and more severe self-reported pain (r = 0.61, P < 0.05), reflecting that patients with activity-avoidance beliefs were less physically fit and experienced more severe pain. The results demonstrate some associations between physical fitness and pain in fibromyalgia and point to the importance of activity avoidance. Although the causal directionality of the associations needs substantiation in clinical research, the findings support the notion that low fitness and activity-avoidance beliefs should be targeted while treating pain in fibromyalgia.

  5. Fibromyalgia patients and controls are equally accurate in detecting tactile stimuli while observing another in pain: an experimental study.

    PubMed

    Vandenbroucke, S; Crombez, G; Harrar, V; Brusselmans, G; Devulder, J; Spence, C; Goubert, L

    2014-11-01

    This study investigated the effects of observing pain in others upon vicarious somatosensory experiences and the detection of somatosensory stimuli in both fibromyalgia (FM) patients and controls. The putative modulatory role of dispositional empathy, hypervigilance to pain, and central sensitization was examined. FM patients (n = 39) and controls (n = 38) saw videos depicting pain-related (hands being pricked) and non-pain-related scenes, while occasionally experiencing vibrotactile stimuli themselves on the left, right, or both hands. Participants reported the location at which they felt a somatosensory stimulus. Tactile and visual scenes were presented in the same spatial location (congruent; e.g., left-left) or from opposite locations (incongruent; e.g., left-right). We calculated the proportion of correct responses, vicarious somatosensory experiences (i.e., trials on which an illusory somatosensory experience was reported while observing pain-related scenes), and neglect errors (i.e., reporting only the site congruent to the visual pain-related information when both hands had been stimulated). Observing another in pain resulted in an equal numbers of vicarious somatosensory experiences in both groups and facilitated the detection of tactile stimuli, especially during spatially congruent trials. Counter to our expectations, this facilitation was not moderated by group. FM patients made fewer neglect errors. Hypervigilance for pain, dispositional empathy, and central sensitization did not exert a modulatory role. Observing pain facilitates the detection of tactile stimuli in FM patients and controls. Overall, a low incidence of vicarious experiences was observed. Further research is needed to understand the role of attentional body focus in the elicitation of vicarious experiences.

  6. Effects of experimental craniofacial pain on fine jaw motor control: a placebo-controlled double-blinded study.

    PubMed

    Kumar, Abhishek; Castrillon, Eduardo; Svensson, Krister G; Baad-Hansen, Lene; Trulsson, Mats; Svensson, Peter

    2015-06-01

    The aim of the experiment was to test the hypothesis that experimental pain in the masseter muscle or temporomandibular joint (TMJ) would perturb the oral fine motor control, reflected in bigger variability of bite force values and jaw muscle activity, during repeated splitting of food morsels. Twenty healthy volunteers participated in four sessions. An intervention was made by injection of either 0.2 ml of monosodium glutamate/isotonic saline (MSG/IS) (randomized) in either the masseter or TMJ (randomized). The participants were asked to hold and split a flat-faced placebo tablet with their anterior teeth, thirty times each at baseline, during intervention and post-intervention. Pain was measured using a 0-10 visual analog scale. The force applied by the teeth to "hold" and "split" the tablet along with the corresponding electromyographic (EMG) activity of the jaw muscles and subject-based reports on perception of pain was recorded. The data analysis included a three-way analysis of variance model. The peak pain intensity was significantly higher during the painful MSG injections in the TMJ (6.1 ± 0.4) than the injections in masseter muscle (5.5 ± 0.5) (P = 0.037). Variability of hold force was significantly smaller during the MSG injection than IS injection in the masseter (P = 0.024). However, there was no significant effect of intervention on the variability of split force during the masseter injections (P = 0.769) and variability of hold and split force during the TMJ injections (P = 0.481, P = 0.545). The variability of the EMG activity of the jaw muscles did not show significant effects of intervention. Subject-based reports revealed that pain did not interfere in the ability to hold the tablet in 57.9 and 78.9 %, and the ability to split the tablet in 78.9 and 68.4 %, of the participants, respectively, during painful masseter and TMJ injections. Hence, experimental pain in the masseter muscle or TMJ did not have any robust effect in terms of bigger

  7. Verbally reinforcing pain reports: an experimental test of the operant model of chronic pain.

    PubMed

    Jolliffe, Christopher D; Nicholas, Michael K

    2004-01-01

    Effective treatments for chronic pain have been based on the operant model for chronic pain, which holds that pain behaviours can be operantly controlled by various reinforcers. Support for the operant model comes primarily from treatment/outcome studies which report significant reductions in pain behaviours in chronic pain patients, but fail to demonstrate the underlying operant thesis that various reinforcers play a significant role in the establishment and maintenance of pain behaviours. In an experimental test of this hypothesis, the pain reports of forty-six healthy undergraduate students were measured over two sets of fifteen trials, in which the pressure from a blood-pressure cuff applied to their arm either remained stable or decreased over time. Half of the subjects received positive verbal reinforcement from the experimenter after each trial if their report of pain intensity exceeded that of the previous trial. Overall, the mean pain reports of reinforced subjects were significantly greater than those of the non-reinforced subjects both when the intensity of the cuff was stable over trials, and when it decreased, as expected. These results provide support for the operant model of chronic pain. The clinical and theoretical implications of these results for the operant model of chronic pain are discussed, and suggestions for future research are made.

  8. Association between Gene Polymorphisms and Pain Sensitivity Assessed in a Multi-Modal Multi-Tissue Human Experimental Model - An Explorative Study.

    PubMed

    Nielsen, Lecia Møller; Olesen, Anne Estrup; Sato, Hiroe; Christrup, Lona Louring; Drewes, Asbjørn Mohr

    2016-10-01

    The genetic influence on sensitivity to noxious stimuli (pain sensitivity) remains controversial and needs further investigation. In the present study, the possible influence of polymorphisms in three opioid receptor (OPRM, OPRD and OPRK) genes and the catechol-O-methyltransferase (COMT) gene on pain sensitivity in healthy participants was investigated. Catechol-O-methyltransferase has an indirect effect on the mu opioid receptor by changing its activity through an altered endogenous ligand effect. Blood samples for genetic analysis were withdrawn in a multi-modal and multi-tissue experimental pain model in 40 healthy participants aged 20-65. Seventeen different single nucleotide polymorphisms in different genes (OPRM, OPRK, OPRD and COMT) were included in the analysis. Experimental pain tests included thermal skin stimulation, mechanical muscle and bone stimulation and mechanical, electrical and thermal visceral stimulations. A cold pressor test was also conducted. DNA was available from 38 of 40 participants. Compared to non-carriers of the COMT rs4680A allele, carriers reported higher bone pressure pain tolerance threshold (i.e. less pain) by up to 23.8% (p < 0.015). Additionally, carriers of the C allele (CC/CT) of OPRK rs6473799 reported a 30.4% higher mechanical visceral pain tolerance threshold than non-carriers (TT; p < 0.019). For the other polymorphisms and stimulations, no associations were found (all p > 0.05). In conclusion, COMT rs4680 and OPRK rs6473799 polymorphisms seem to be associated with pain sensitivity. Thus, the findings support a possible genetic influence on pain sensitivity. © 2016 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).

  9. Pain referral and regional deep tissue hyperalgesia in experimental human hip pain models.

    PubMed

    Izumi, Masashi; Petersen, Kristian Kjær; Arendt-Nielsen, Lars; Graven-Nielsen, Thomas

    2014-04-01

    Hip disorder patients typically present with extensive pain referral and hyperalgesia. To better understand underlying mechanisms, an experimental hip pain model was established in which pain referrals and hyperalgesia could be studied under standardized conditions. In 16 healthy subjects, pain was induced by hypertonic saline injection into the gluteus medius tendon (GMT), adductor longus tendon (ALT), or gluteus medius muscle (GMM). Isotonic saline was injected contralaterally as control. Pain intensity was assessed on a visual analogue scale (VAS), and subjects mapped the pain distribution. Before, during, and after injections, passive hip joint pain provocation tests were completed, together with quantitative sensory testing as follows: pressure pain thresholds (PPTs), cuff algometry pain thresholds (cuff PPTs), cutaneous pin-prick sensitivity, and thermal pain thresholds. Hypertonic saline injected into the GMT resulted in higher VAS scores than hypertonic injections into the ALT and GMM (P<.05). Referred pain areas spread to larger parts of the leg after GMT and GMM injections compared with more regionalized pain pattern after ALT injections (P<.05). PPTs at the injection site were decreased after hypertonic saline injections into GMT and GMM compared with baseline, ALT injections, and isotonic saline. Cuff PPTs from the thigh were decreased after hypertonic saline injections into the ALT compared with baseline, GMT injections, and isotonic saline (P<.05). More subjects had positive joint pain provocation tests after hypertonic compared with isotonic saline injections (P<.05), indicating that this provocation test also assessed hyperalgesia in extra-articular soft tissues. The experimental models may open for better understanding of pain mechanisms associated with painful hip disorders.

  10. Affect balance style, experimental pain sensitivity, and pain-related responses

    PubMed Central

    Sibille, Kimberly T.; Kindler, Lindsay L.; Glover, Toni L.; Staud, Roland; Riley, Joseph L.; Fillingim, Roger B.

    2011-01-01

    Objectives Affect is neurobiologically based, influences emotions, contributes to temperamental characteristics, and can be evaluated from both a state and trait perspective. Associations between state-related positive affect (PA), negative affect (NA), and chronic pain have been investigated. However, little is known about the relationship between trait affect patterns and pain-related experiences. Affect balance style (ABS) provides a framework to assess the combined contribution of trait PA and NA. Psychological factors and experimental pain sensitivity are indicated as predictors of chronic pain onset. The current study investigated the relationship between ABS, pain sensitivity, and pain-related measures in healthy adults. Methods Subjects (n=372) completed quantitative sensory testing, pain-related questionnaires, and the Positive and Negative Affect Scale (PANAS). ABS groups were categorized as Healthy (high PA, low NA), Low (low PA, low NA), Depressive (low PA, high NA), and Reactive (high PA, high NA). Z-scores were computed for three experimental pain measures: ischemic, pressure, and heat. Results ABS groups significantly differed on ischemic pain sensitivity and pain-related measures. Specifically, the Healthy group demonstrated lower ischemic pain sensitivity compared to the Reactive group (p=0.02); the Depressive and Reactive groups endorsed higher somatic symptoms compared to the Healthy group (p<0.02); the Low and Depressive groups reported more physical stimuli sensitivity than the Healthy group (p<0.02); and the Reactive group indicated more passive coping strategies then the Low and Healthy groups (p=0.001). Discussion Findings from the study suggest that among healthy adults, trait affect patterns are associated with ischemic experimental pain sensitivity and other pain-related measures. PMID:22367502

  11. Affect balance style, experimental pain sensitivity, and pain-related responses.

    PubMed

    Sibille, Kimberly T; Kindler, Lindsay L; Glover, Toni L; Staud, Roland; Riley, Joseph L; Fillingim, Roger B

    2012-06-01

    Affect is neurobiologically based, influences emotions, contributes to temperamental characteristics, and can be evaluated from both state and trait perspectives. Associations between state-related positive affect (PA), negative affect (NA), and chronic pain have been investigated. However, little is known about the relationship between trait affect patterns and pain-related experiences. Affect balance style (ABS) provides a framework to assess the combined contribution of trait PA and NA. Psychological factors and experimental pain sensitivity are indicated as predictors of chronic pain onset. The current study investigated the relationship between ABS, pain sensitivity, and pain-related measures in healthy adults. Participants (n=372) completed quantitative sensory testing, pain-related questionnaires, and the Positive and Negative Affect Scale. ABS groups were categorized as Healthy (high PA, low NA), Low (low PA, low NA), Depressive (low PA, high NA), and Reactive (high PA, high NA). Z-scores were computed for 3 experimental pain measures: ischemic, pressure, and heat. ABS groups significantly differed on ischemic pain sensitivity and pain-related measures. Specifically, the Healthy group demonstrated lower ischemic pain sensitivity compared with the Reactive group (P=0.02); the Depressive and Reactive groups endorsed higher somatic symptoms compared with the Healthy group (P<0.02); the Low and Depressive groups reported more physical stimuli sensitivity than the Healthy group (P<0.02); and the Reactive group indicated more passive coping strategies then the Low and Healthy groups (P=0.001). Findings from the study suggest that among healthy adults, trait affect patterns are associated with ischemic experimental pain sensitivity and other pain-related measures.

  12. The effect of experimentally-induced subacromial pain on proprioception.

    PubMed

    Sole, Gisela; Osborne, Hamish; Wassinger, Craig

    2015-02-01

    Shoulder injuries may be associated with proprioceptive deficits, however, it is unknown whether these changes are due to the experience of pain, tissue damage, or a combination of these. The aim of this study was to investigate the effect of experimentally-induced sub-acromial pain on proprioceptive variables. Sub-acromial pain was induced via hypertonic saline injection in 20 healthy participants. Passive joint replication (PJR) and threshold to detection of movement direction (TTDMD) were assessed with a Biodex System 3 Pro isokinetic dynamometer for baseline control, experimental pain and recovery control conditions with a starting position of 60° shoulder abduction. The target angle for PJR was 60° external rotation, starting from 40°. TTDMD was tested from a position of 20° external rotation. Repeated measures ANOVAs were used to determine differences between PJR absolute and variable errors and TTDMD for the control and experimental conditions. Pain was elicited with a median 7 on the Numeric Pain Rating Scale. TTDMD was significantly decreased for the experimental pain condition compared to baseline and recovery conditions (≈30%, P = 0.003). No significant differences were found for absolute (P = 0.152) and variable (P = 0.514) error for PJR. Movement sense was enhanced for the experimental sub-acromial pain condition, which may reflect protective effects of the central nervous system in response to the pain. Where decreased passive proprioception is observed in shoulders with injuries, these may be due to a combination of peripheral tissue injury and neural adaptations that differ from those due to acute pain. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Puncture of a lumbar intervertebral disc induces changes in spontaneous pain behavior: an experimental study in rats.

    PubMed

    Olmarker, Kjell

    2008-04-15

    Changes in spontaneous behavior was studied in rats after a controlled puncture of a lumbar intervertebral disc. To study if puncture of a lumbar disc would induce recordable changes in spontaneous pain behavior. Anular tears are common and may be found both in patients with low back pain and in asymptomatic patients. It has been suggested that anular injury may relate to low back pain either by stimulation of local sensory receptors in the posterior part of the anulus fibrosus or by ingrowth of newly formed nerve fibers into the deeper parts of the disc. The objective of the study was to analyze if a controlled puncture of a lumbar intervertebral disc might induce recordable changes in spontaneous behavior of rats. After anesthesia, the L4-L5 disc was punctured in 10 rats. Ten other rats received sham surgery. Spontaneous behavior was assessed at days 1, 3, 7, 14, and 21 after surgery. Statistically significant differences in behavior were seen at all days analyzed. Most consistent were increases in "grooming" and in "wet-dog shakes." Puncture of a lumbar intervertebral disc in the rat produces changes in spontaneous behavior mainly seen as increased "grooming" and "wet-dog shakes," 2 behaviors that have been suggested to indicate stress and pain.

  14. Pain by Association? Experimental Modulation of Human Pain Thresholds Using Classical Conditioning.

    PubMed

    Madden, Victoria J; Bellan, Valeria; Russek, Leslie N; Camfferman, Danny; Vlaeyen, Johan W S; Moseley, G Lorimer

    2016-10-01

    A classical conditioning framework is often used for clinical reasoning about pain that persists after tissue healing. However, experimental studies demonstrating classically conditioned pain in humans are lacking. The current study tested whether non-nociceptive somatosensory stimuli can come to modulate pain thresholds after being paired with painful nociceptive stimuli in healthy humans. We used a differential simultaneous conditioning paradigm in which one nonpainful vibrotactile conditioned stimulus (CS(+)) was simultaneously paired with an unconditioned painful laser stimulus, and another vibrotactile stimulus (CS(-)) was paired with a nonpainful laser stimulus. After acquisition, at-pain-threshold laser stimuli were delivered simultaneously with a CS(+) or CS(-) vibrotactile stimulus. The primary outcome was the percentage of at-threshold laser stimuli that were reported as painful. The results were as expected: after conditioning, at-threshold laser trials paired with the CS(+) were reported as painful more often, as more intense, and as more unpleasant than those paired with the CS(-). This study provides new evidence that pain thresholds can be modulated via classical conditioning, even when the stimulus used to test the threshold cannot be anticipated. As such, it lays a critical foundation for further investigations of classical conditioning as a possible driver of persistent pain. This study provides new evidence that human pain thresholds can be influenced by non-nociceptive somatosensory stimuli, via a classical conditioning effect. As such, it lays a critical foundation for further investigations of classical conditioning as a possible driver of persistent pain. Copyright © 2016 American Pain Society. Published by Elsevier Inc. All rights reserved.

  15. Ischemic compression and joint mobilisation for the treatment of nonspecific myofascial foot pain: findings from two quasi-experimental before-and-after studies

    PubMed Central

    Hains, Guy; Boucher, Pierre B.; Lamy, Anne-Marie

    2015-01-01

    Objective: The aim of this study was to evaluate the efficacy of myofascial therapy involving ischemic compression on trigger points in combination with mobilization therapy on patients with chronic nonspecific foot pain. Study design: Two quasi-experimental before-and-after studies involving two different baseline states. Method: Foot pain patients at a private clinic were divided into two separate cohorts: A, custom orthotic users; and B, non-users. In Study A, 31 users received 15 experimental treatments consisting of ischemic compressions on trigger points and mobilization of articulations through the foot immediately after study enrollment. In study B, ten non-users were prescribed a soft prefabricated insole and were monitored for five weeks before subsequently receiving 15 experimental treatments after the initial five-week delay. Outcome measures: The Foot Function Index (FFI) and patients’ perceived improvement score (PIS) on a scale from 0% to 100%. Results: The Study A group (n=31) maintained a significant reduction in the FFI at all three follow-up evaluations. Mean improvement from baseline in FFI was 47%, 49% and 56% at 0, 1 and 6 months, respectively, post-treatment. Mean PIS was 58%, 57%, and 58%, again at 0, 1 and 6 months post-treatment. For the Study B group, mean improvement in FFI was only 19% after the monitoring period, and 64% after the experimental treatment period. Mean PIS was 31% after monitoring, and 78% after experimental treatment. In repeated measures analyses, experimental treatment was associated with a significant main effect in both of these before-and after studies (all P values<0.01). Conclusion: Combined treatment involving ischemic compression and joint mobilization for chronic foot pain is associated with significant improvements in functional and self-perceived improvement immediately and at up to six-months post-treatment. Further validation of this treatment approach within a randomized controlled trial is needed. PMID

  16. Effect of inhalation aromatherapy with lavender essence on pain associated with intravenous catheter insertion in preschool children: A quasi-experimental study.

    PubMed

    Bikmoradi, Ali; Khaleghverdi, Masoomeh; Seddighi, Iraj; Moradkhani, Shirin; Soltanian, Alireza; Cheraghi, Fatemeh

    2017-08-01

    The aim of this study was to assess the effect of inhalation aromatherapy with lavender essence on the pain severity of intravenous catheter insertion in hospitalized preschool children. A quasi-experimental study involving 60 participants using convenience sampling were assigned to control (n = 30) and aromatherapy (n = 30) groups. Children in the aromatherapy group inhaled 5 drops of the essence, while children in the control group inhaled 5 drops of distilled water, 20 min before venipuncture. Pain severity was measured using OUCHER scale 10 min after catheterization. Mean of pain severity between the aromatherapy and control groups demonstrated a significant difference immediately (P = 0.002) and 5 (P = 0.001) and 10 min (P = 0.01) after intravenous catheter insertion. Mean of pain severity in the three assessed time points had significant differences in aromatherapy and control groups (P = 0.001). Aromatherapy with Lavender essence helped to reduce pain severity of intravenous catheter insertion in children. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. A Novel Magnetic Stimulator Increases Experimental Pain Tolerance in Healthy Volunteers - A Double-Blind Sham-Controlled Crossover Study

    PubMed Central

    Kortekaas, Rudie; Konopka, Karl-Heinz; Harbers, Marten; van der Hoeven, Johannes H.; van Wijhe, Marten; Aleman, André; Maurits, Natasha M.

    2013-01-01

    The ‘complex neural pulse’TM (CNP) is a neuromodulation protocol employing weak pulsed electromagnetic fields (PEMF). A pioneering paper reported an analgesic effect in healthy humans after 30 minutes of CNP-stimulation using three nested whole head coils. We aimed to devise and validate a stimulator with a novel design entailing a multitude of small coils at known anatomical positions on a head cap, to improve applicability. The main hypothesis was that CNP delivery with this novel device would also increase heat pain thresholds. Twenty healthy volunteers were enrolled in this double-blind, sham-controlled, crossover study. Thirty minutes of PEMF (CNP) or sham was applied to the head. After one week the other treatment was given. Before and after each treatment, primary and secondary outcomes were measured. Primary outcome was heat pain threshold (HPT) measured with thermal quantitative sensory testing. Other outcomes were warmth detection threshold, and aspects of cognition, emotion and motor performance. As hypothesized heat pain threshold was significantly increased after the PEMF stimulation. All other outcomes were unaltered by the PEMF but there was a trend level reduction of cognitive performance after PEMF stimulation as measured by the digit-symbol substitution task. Results from this pilot study suggest that our device is able to stimulate the brain and to modulate its function. This is in agreement with previous studies that used similar magnetic field strengths to stimulate the brain. Specifically, pain control may be achieved with PEMF and for this analgesic effect, coil design does not appear to play a dominant role. In addition, the flexible configuration with small coils on a head cap improves clinical applicability. Trial Registration Dutch Cochrane Centre NTR1093 PMID:23620795

  18. Experimentally induced pain perception is acutely reduced by aerobic exercise in people with chronic low back pain.

    PubMed

    Hoffman, Martin D; Shepanski, Melissa A; Mackenzie, Sean P; Clifford, Philip S

    2005-01-01

    This study examined whether subjects with chronic low back pain demonstrate exercise-induced analgesia to experimentally induced pressure pain. We employed a repeated measures design to study eight subjects with chronic low back pain (mean +/- standard deviation age = 40 +/- 10, duration of pain = 7 +/- 4 years). Pain ratings were measured immediately before and 2 minutes and 32 minutes after 25 minutes of cycle ergometry (5 minutes at 50% peak oxygen uptake, then 20 minutes at 70% peak oxygen uptake). We based the pain ratings on subject input on a visual analog scale at 10-second intervals during the 2-minute pressure pain stimulus to the nondominant index finger. Compared with preexercise values, pain ratings were significantly (p < 0.05) decreased after exercise at both 2 and 32 minutes postexercise. We conclude that pressure pain perception can be reduced for more than 30 minutes following aerobic exercise from leg cycling among people with chronic low back pain.

  19. SPONTANEOUS CHRONIC PAIN AFTER EXPERIMENTAL THORACTOMY REVEALED BY CONDITIONED PLACE PREFERENCE: morphine differentiates tactile evoked pain from spontaneous pain

    PubMed Central

    Hung, Ching-Hsia; Wang, Jeffrey Chi-Fei; Strichartz, Gary

    2015-01-01

    Chronic pain following surgery limits social activity, interferes with work and causes emotional suffering. A major component of such pain is is reported as “resting” or spontaneous pain with no apparent external stimulus. Although experimental animal models can simulate the stimulus-evoked chronic pain that occurs after surgery, there have been no studies of spontaneous chronic pain in such models. Here the Conditioned Place Preference (CPP) paradigm was used to reveal resting pain after experimental thoracotomy. Male Sprague-Dawley rats received a thoracotomy with 1 hour rib retraction, resulting in evoked tactile hypersensitivity, previously shown to last for at least 9 weeks. Intraperitoneal injections of morphine (2.5 mg/kg) or gabapentin (40mg/kg) gave equivalent 2-3h long relief of tactile hypersensitivity, when tested 12-14 days post-operative. In separate experiments, single trial CPP was conducted 1 week before thoracotomy and then 12 days (gabapentin) or 14 days (morphine) after surgery, followed the next day by one conditioning sesssion with morphine or gabapentin, both vs saline. The gabapentin-conditioned, but not the morphine-conditioned rats showed a significant preference for the analgesia-paired chamber, despite the two agents’ equivalent effect in relieving tactile allodynia. These results show that experimental thoracotomy in rats causes spontaneous pain, and that some analgesics, such as morphine, that reduce evoked pain do not also relieve resting pain, suggesting that pathophysiological mechanisms differ between these two aspects of long-term post-operative pain. PMID:26116369

  20. An experimental study on the effectiveness of acupressure with aromatic lavender essential oil for sub-acute, non-specific neck pain in Hong Kong.

    PubMed

    Yip, Y B; Tse, Sonny Hing-Min

    2006-02-01

    To assess the efficacy of acupressure using an aromatic essential oil (lavender) as an add-on treatment for pain relief and enhancing physical functional activities among adults with sub-acute non-specific neck pain. Experimental study design. The Telehealth clinic and the community centre, Hong Kong. A course of 8-session manual acupressure with lavender oil over a 3 week period. Changes from baseline to the end of treatment were assessed on neck pain intensity [by Visual Analogue Scale (VAS)]; stiffness level; stress level; neck lateral flexion, forward flexion and extension in cm, and interference with daily activities. The baseline VAS score for the intervention and control groups were 5.12 and 4.91 out of 10, respectively (P = 0.72). One month after the end of treatment, compared to the control group, the manual acupressure group had 23% reduced pain intensity (P = 0.02), 23% reduced neck stiffness (P = 0.001), 39% reduced stress level (P = 0.0001), improved neck flexion (P = 0.02), neck lateral flexion (P = 0.02), and neck extension (P = 0.01). However, improvements in functional disability level were found in both the manual acupressure group (P = 0.001) and control group (P = 0.02). Our results show that eight sessions of acupressure with aromatic lavender oil were an effective method for short-term neck pain relief.

  1. Interaction between histamine-induced itch and experimental muscle pain.

    PubMed

    Wasner, G; Schwarz, K; Schattschneider, J; Binder, A; Jensen, T S; Baron, R

    2004-06-01

    Itch sensation can be inhibited by simultaneously applied cutaneous pain at the same skin site via a central mechanism. Deep muscle pain is often associated with sensory changes in the corresponding dermatome. We investigated whether experimentally induced muscle pain has any influence on histamine-induced itch and vice versa in a double blind placebo-controlled study. Experiments were performed in 18 healthy subjects. In nine individuals control iontophoresis of histamine into the forearm produced a distinct itch sensation. Another nine individuals participated in an additional experiment in which histamine and saline were iontophoresed on the forearm in a randomized double-blinded two-way crossover design after intramuscular injection of capsaicin into the ipsilateral brachioradial muscle. Capsaicin-induced muscle pain reduced itch sensation significantly. In contrast, capsaicin-induced muscle pain increased significantly after cutaneous histamine application compared to muscle pain after iontophoresis of saline (placebo). These novel data indicate that muscle pain inhibits itch and histamine increases muscle pain. A bi-directional interaction between cutaneous histamine-sensitive afferents and nociceptive muscle afferents via central mechanisms is suggested.

  2. Effects of a home-exercise therapy programme on cervical and lumbar range of motion among nurses with neck and lower back pain: a quasi-experimental study.

    PubMed

    Freimann, Tiina; Merisalu, Eda; Pääsuke, Mati

    2015-01-01

    Cervical and lumbar range of motion limitations are usually associated with musculoskeletal pain in the neck and lower back, and are a major health problem among nurses. Physical exercise has been evaluated as an effective intervention method for improving cervical and lumbar range of motion, and for preventing and reducing musculoskeletal pain. The purpose of this study was to investigate the effects of a home-exercise therapy programme on cervical and lumbar range of motion among intensive care unit nurses who had experienced mild to moderate musculoskeletal pain in the neck and or lower back during the previous six months. A quasi-experimental study was conducted among intensive care unit nurses at Tartu University Hospital (Estonia) between May and July 2011. Thirteen nurses who had suffered musculoskeletal pain episodes in the neck and or lower back during the previous six months underwent an 8-week home-exercise therapy programme. Eleven nurses without musculoskeletal pain formed a control group. Questions from the Nordic Musculoskeletal Questionnaire and the 11-point Visual Analogue Scale were used to select potential participants for the experimental group via an assessment of the prevalence and intensity of musculoskeletal pain. Cervical range of motion and lumbar range of motion in flexion, extension, lateral flexion and (cervical range of motion only) rotation were measured with a digital goniometer. A paired t-test was used to compare the measured parameters before and after the home-exercise therapy programme. A Student's t-test was used to analyse any differences between the experimental and control groups. After the home-exercise therapy, there was a significant increase (p < 0.05) in cervical range of motion in flexion, extension, lateral flexion and rotation, and in lumbar range of motion in lateral flexion. Cervical range of motion in flexion was significantly higher (p < 0.01) in the experimental group compared to the control group after

  3. The Web-Based Osteoarthritis Management Resource My Joint Pain Improves Quality of Care: A Quasi-Experimental Study.

    PubMed

    Umapathy, Hema; Bennell, Kim; Dickson, Chris; Dobson, Fiona; Fransen, Marlene; Jones, Graeme; Hunter, David J

    2015-07-07

    Despite the availability of evidence-based guidelines for conservative treatment of osteoarthritis (OA), management is often confined to the use of analgesics and waiting for eventual total joint replacement. This suggests a gap in knowledge for persons with OA regarding the many different treatments available to them. Our objective was to evaluate outcomes after usage of a Web-based resource called My Joint Pain that contains tailored, evidence-based information and tools aimed to improve self-management of OA on self-management and change in knowledge. A quasi-experimental design was used to evaluate the My Joint Pain website intervention over a 12-month period. The intervention provided participants with general and user-specific information, monthly assessments with validated instruments, and progress-tracking tools. A nationwide convenience sample of 195 participants with self-assessed hip and/or knee OA completed both baseline and 12-month questionnaires (users: n=104; nonusers: n=91). The primary outcome measure was the Health Evaluation Impact Questionnaire (heiQ) to evaluate 8 different domains (health-directed activity, positive and active engagement in life, emotional distress, self-monitoring and insight, constructive attitudes and approaches, skill and technique acquisition, social integration and support, health service navigation) and the secondary outcome measure was the 17-item Osteoarthritis Quality Indicator (OAQI) questionnaire to evaluate the change in appropriateness of care received by participants. Independent t tests were used to compare changes between groups for the heiQ and chi-square tests to identify changes within and between groups from baseline to 12 months for each OAQI item. Baseline demographics between groups were similar for gender (152/195, 77.9% female), age (mean 60, SD 9 years) and body mass index (mean 31.1, SD 6.8 kg/m(2)). With the exception of health service navigation, mean effect sizes from all other heiQ domains

  4. Effects of Extracorporeal Shock Wave Therapy on Pain in Patients With Chronic Refractory Coccydynia: A Quasi-Experimental Study.

    PubMed

    Haghighat, Shila; Mashayekhi Asl, Mahboobeh

    2016-08-01

    Several nonsurgical and surgical treatment modalities are available for patients with chronic coccydynia, with controversial results. Extracorporeal shock wave therapy (ECSWT) is effective in the treatment of many musculoskeletal disorders; however, it has not been tested for chronic coccydynia. We performed the current study to determine the effects of ECSWT on pain in patients with chronic coccydynia. This quasi-interventional clinical study included 10 patients with chronic coccydynia without acute fracture. All the patients received ECSWT with a radial probe delivering 3,000 shock waves of 2 bar per session at 21 Hz frequency directed to the coccyx. Each patient received four sessions of ECSWT at one-week intervals. The pain severity was recorded according to the visual analog scale (VAS) at one, two, three, and four weeks after initiation of therapy. The VAS score was also evaluated at one and six months after ending the therapy. Most of the participants were women (90.0%), and the participants' mean age was 39.1 ± 9.1 (ranging from 28 to 52) years. The VAS score did not decrease significantly seven months after therapy when compared to baseline (3.3 ± 3.6 vs. 7.3 ± 2.1; P = 0.011). However, the VAS score at two months (2.6 ± 2.9 vs. 7.3 ± 2.1; P = 0.007) and at four weeks (3.2 ± 2.8 vs. 7.3 ± 2.1; P = 0.007) significantly decreased when compared to baseline. The decrease in VAS scores was not persistent after cessation of the therapy. ECSWT is an effective modality in relieving the pain intensity in patients with refractory chronic coccydynia for the early period after intervention.

  5. Effects of Extracorporeal Shock Wave Therapy on Pain in Patients With Chronic Refractory Coccydynia: A Quasi-Experimental Study

    PubMed Central

    Haghighat, Shila; Mashayekhi Asl, Mahboobeh

    2016-01-01

    Background Several nonsurgical and surgical treatment modalities are available for patients with chronic coccydynia, with controversial results. Extracorporeal shock wave therapy (ECSWT) is effective in the treatment of many musculoskeletal disorders; however, it has not been tested for chronic coccydynia. Objectives We performed the current study to determine the effects of ECSWT on pain in patients with chronic coccydynia. Patients and Methods This quasi-interventional clinical study included 10 patients with chronic coccydynia without acute fracture. All the patients received ECSWT with a radial probe delivering 3,000 shock waves of 2 bar per session at 21 Hz frequency directed to the coccyx. Each patient received four sessions of ECSWT at one-week intervals. The pain severity was recorded according to the visual analog scale (VAS) at one, two, three, and four weeks after initiation of therapy. The VAS score was also evaluated at one and six months after ending the therapy. Results Most of the participants were women (90.0%), and the participants’ mean age was 39.1 ± 9.1 (ranging from 28 to 52) years. The VAS score did not decrease significantly seven months after therapy when compared to baseline (3.3 ± 3.6 vs. 7.3 ± 2.1; P = 0.011). However, the VAS score at two months (2.6 ± 2.9 vs. 7.3 ± 2.1; P = 0.007) and at four weeks (3.2 ± 2.8 vs. 7.3 ± 2.1; P = 0.007) significantly decreased when compared to baseline. The decrease in VAS scores was not persistent after cessation of the therapy. Conclusions ECSWT is an effective modality in relieving the pain intensity in patients with refractory chronic coccydynia for the early period after intervention. PMID:27843777

  6. Assessing analgesic actions of opioids by experimental pain models in healthy volunteers – an updated review

    PubMed Central

    Staahl, Camilla; Olesen, Anne Estrup; Andresen, Trine; Arendt-Nielsen, Lars; Drewes, Asbjørn Mohr

    2009-01-01

    AIM Experimental pain models may help to evaluate the mechanisms of action of analgesics and target the clinical indications for their use. This review addresses how the efficacy of opioids can be assessed in human volunteers using experimental pain models. The drawback with the different study designs is also discussed. METHOD A literature search was completed for randomized controlled studies which included human experimental pain models, healthy volunteers and opioids. RESULTS Opioids with a strong affinity for the µ-opioid receptor decreased the sensation in a variety of experimental pain modalities, but strong tonic pain was attenuated more than short lasting pain and non-painful sensations. The effects of opioids with weaker affinity for the µ-opioid receptor were detected by a more narrow range of pain models, and the assessment methods needed to be more sensitive. CONCLUSION The way the pain is induced, assessed and summarized is very important for the sensitivity of the pain models. This review gives an overview of how different opioids perform in experimental pain models. Generally experimental pain models need to be designed with careful consideration of pharmacological mechanisms and pharmacokinetics of analgesics. This knowledge can aid the decisions needed to be taken when designing experimental pain studies for compounds entering phase 1 clinical trials. PMID:19694733

  7. Differences in pain-related fear acquisition and generalization: an experimental study comparing patients with fibromyalgia and healthy controls.

    PubMed

    Meulders, Ann; Jans, Anne; Vlaeyen, Johan W S

    2015-01-01

    Anomalies in fear learning, such as failure to inhibit fear to safe stimuli, lead to sustained anxiety, which in turn may augment pain. In the same vein, stimulus generalization is adaptive as it enables individuals to extrapolate the predictive value of 1 stimulus to similar stimuli. However, when fear spreads in an unbridled way to novel technically safe stimuli, stimulus generalization becomes maladaptive and may lead to dysfunctional avoidance behaviors and culminate in severe pain disability. In a voluntary movement conditioning paradigm, we compared the acquisition and generalization of pain-related fear in patients with fibromyalgia (FM) and healthy controls. During acquisition, participants received predictable pain in 1 context (ie, 1 movement predicts pain, whereas another does not), and unpredictable pain in another (ie, pain never contingent upon movement). Fear generalization to novel movements (resembling the original painful or nonpainful movement) was tested in both contexts. Results indicated that the FM group showed slower differential acquisition of pain-related fear in the predictable context, and more contextual pain-related fear in the unpredictable context. Fear of movement-related pain spreads selectively to novel movements similar to the original painful movement, and not to those resembling the nonpainful movement in the healthy controls, but nondifferential fear generalization was observed in FM. As expected, in the unpredictable context, we also observed nondifferential fear generalization; this effect was more pronounced in FM. Given the status of overgeneralization as a plausible transdiagnostic pathogenic marker, we believe that this research might increase our knowledge about pathogenesis of musculoskeletal widespread pain.

  8. Effects of hypnotic analgesia and hypnotizability on experimental ischemic pain.

    PubMed

    DeBenedittis, G; Panerai, A A; Villamira, M A

    1989-01-01

    Mechanisms of hypnotic analgesia are still poorly understood and conflicting data are reported regarding the underlying neurochemical correlates. The present study was designed to investigate the effects of hypnotically induced analgesia and hypnotizability on experimental ischemic pain, taking into account pain and distress tolerance as well as the neurochemical correlates. 11 high hypnotizable Ss and 10 low hypnotizable Ss, as determined by scores on the Stanford Hypnotic Susceptibility Scale, Form C (Weitzenhoffer & E. R. Hilgard, 1962), were administered an ischemic pain test in both waking and hypnotic conditions. The following variables were measured: (a) pain and distress tolerance, (b) anxiety levels, and (c) plasma concentrations of beta-endorphin and adrenocorticotropic hormone (ACTH). Results confirmed significant increases of pain and distress tolerance during hypnosis as compared to the waking state, with positive correlations between pain and distress relief and hypnotizability. Moreover, a hypnotically induced dissociation between the sensory-discriminative and the affective-motivational dimensions of pain experience was found, but only in high hypnotizable Ss. Hypnotic analgesia was unrelated to anxiety reduction and was not mediated either by endorphins or by ACTH.

  9. Hypnosis and Local Anesthesia for Dental Pain Relief-Alternative or Adjunct Therapy?-A Randomized, Clinical-Experimental Crossover Study.

    PubMed

    Wolf, Thomas Gerhard; Wolf, Dominik; Callaway, Angelika; Below, Dagna; d'Hoedt, Bernd; Willershausen, Brita; Daubländer, Monika

    2016-01-01

    This prospective randomized clinical crossover trial was designed to compare hypnosis and local anesthesia for experimental dental pain relief. Pain thresholds of the dental pulp were determined. A targeted standardized pain stimulus was applied and rated on the Visual Analogue Scale (0-10). The pain threshold was lower under hypnosis (58.3 ± 17.3, p < .001), maximal (80.0) under local anesthesia. The pain stimulus was scored higher under hypnosis (3.9 ± 3.8) than with local anesthesia (0.0, p < .001). Local anesthesia was superior to hypnosis and is a safe and effective method for pain relief in dentistry. Hypnosis seems to produce similar effects observed under sedation. It can be used in addition to local anesthesia and in individual cases as an alternative for pain control in dentistry.

  10. Experimental pain phenotyping in community-dwelling individuals with knee osteoarthritis.

    PubMed

    Cardoso, Josue S; Riley, Joseph L; Glover, Toni; Sibille, Kimberly T; Bartley, Emily J; Goodin, Burel R; Bulls, Hailey W; Herbert, Matthew; Addison, Adriana S; Staud, Roland; Redden, David T; Bradley, Laurence A; Fillingim, Roger B; Cruz-Almeida, Yenisel

    2016-09-01

    Pain among individuals with knee osteoarthritis (OA) is associated with significant disability in older adults, and recent evidence demonstrates enhanced experimental pain sensitivity. Although previous research showed considerable heterogeneity in the OA clinical pain presentation, less is known regarding the variability in responses to experimental pain. The present study included individuals with knee OA (n = 292) who participated in the Understanding Pain and Limitations in Osteoarthritic Disease study and completed demographic and psychological questionnaires followed by a multimodal quantitative sensory testing (QST) session. Quantitative sensory testing measures were subjected to variable reduction procedures to derive pain sensitivity index scores, which in turn were entered into a cluster analysis. Five clusters were significantly different across all pain sensitivity index variables (P < 0.001) and were characterized by: (1) low pain sensitivity to pressure pain (N = 39); (2) average pain sensitivity across most modalities (N = 88); (3) high temporal summation of punctate pain (N = 38); (4) high cold pain sensitivity (N = 80); and (5) high sensitivity to heat pain and temporal summation of heat pain (N = 41). Clusters differed significantly by race, gender, somatic reactivity, and catastrophizing (P < 0.05). Our findings support the notion that there are distinct subgroups or phenotypes based on experimental pain sensitivity in community-dwelling older adults with knee OA, expanding previous findings of similar cluster characterizations in healthy adults. Future research is needed to further understand the pathophysiological mechanisms underlying pain within these subgroups, which may be of added value in tailoring effective treatments for people with OA.

  11. Nonpainful wide-area compression inhibits experimental pain

    PubMed Central

    Honigman, Liat; Bar-Bachar, Ofrit; Yarnitsky, David; Sprecher, Elliot; Granovsky, Yelena

    2016-01-01

    Abstract Compression therapy, a well-recognized treatment for lymphoedema and venous disorders, pressurizes limbs and generates massive non-noxious afferent sensory barrages. The aim of this study was to study whether such afferent activity has an analgesic effect when applied on the lower limbs, hypothesizing that larger compression areas will induce stronger analgesic effects, and whether this effect correlates with conditioned pain modulation (CPM). Thirty young healthy subjects received painful heat and pressure stimuli (47°C for 30 seconds, forearm; 300 kPa for 15 seconds, wrist) before and during 3 compression protocols of either SMALL (up to ankles), MEDIUM (up to knees), or LARGE (up to hips) compression areas. Conditioned pain modulation (heat pain conditioned by noxious cold water) was tested before and after each compression protocol. The LARGE protocol induced more analgesia for heat than the SMALL protocol (P < 0.001). The analgesic effect interacted with gender (P = 0.015). The LARGE protocol was more efficient for females, whereas the MEDIUM protocol was more efficient for males. Pressure pain was reduced by all protocols (P < 0.001) with no differences between protocols and no gender effect. Conditioned pain modulation was more efficient than the compression-induced analgesia. For the LARGE protocol, precompression CPM efficiency positively correlated with compression-induced analgesia. Large body area compression exerts an area-dependent analgesic effect on experimental pain stimuli. The observed correlation with pain inhibition in response to robust non-noxious sensory stimulation may suggest that compression therapy shares similar mechanisms with inhibitory pain modulation assessed through CPM. PMID:27152691

  12. Nonpainful wide-area compression inhibits experimental pain.

    PubMed

    Honigman, Liat; Bar-Bachar, Ofrit; Yarnitsky, David; Sprecher, Elliot; Granovsky, Yelena

    2016-09-01

    Compression therapy, a well-recognized treatment for lymphoedema and venous disorders, pressurizes limbs and generates massive non-noxious afferent sensory barrages. The aim of this study was to study whether such afferent activity has an analgesic effect when applied on the lower limbs, hypothesizing that larger compression areas will induce stronger analgesic effects, and whether this effect correlates with conditioned pain modulation (CPM). Thirty young healthy subjects received painful heat and pressure stimuli (47°C for 30 seconds, forearm; 300 kPa for 15 seconds, wrist) before and during 3 compression protocols of either SMALL (up to ankles), MEDIUM (up to knees), or LARGE (up to hips) compression areas. Conditioned pain modulation (heat pain conditioned by noxious cold water) was tested before and after each compression protocol. The LARGE protocol induced more analgesia for heat than the SMALL protocol (P < 0.001). The analgesic effect interacted with gender (P = 0.015). The LARGE protocol was more efficient for females, whereas the MEDIUM protocol was more efficient for males. Pressure pain was reduced by all protocols (P < 0.001) with no differences between protocols and no gender effect. Conditioned pain modulation was more efficient than the compression-induced analgesia. For the LARGE protocol, precompression CPM efficiency positively correlated with compression-induced analgesia. Large body area compression exerts an area-dependent analgesic effect on experimental pain stimuli. The observed correlation with pain inhibition in response to robust non-noxious sensory stimulation may suggest that compression therapy shares similar mechanisms with inhibitory pain modulation assessed through CPM.

  13. Ultrasound guided, painful electrical stimulation of lumbar facet joint structures: an experimental model of acute low back pain.

    PubMed

    O'Neill, Søren; Graven-Nielsen, Thomas; Manniche, Claus; Arendt-Nielsen, Lars

    2009-07-01

    Quantitative sensory testing has indicated generalized muscle hyperalgesia in patients with chronic low back pain. The temporal development of such hyperalgesia is not well understood. The aim of the present study was to demonstrate whether generalized muscle hyperalgesia can develop within minutes of acute low back pain using a new experimental model of lumbar facet joint pain. Thirteen healthy volunteers were included and baseline pressure pain thresholds were assessed at eight separate sites, outside the area of evoked low back and referred pain. Using ultrasonography, two electrode needles were placed either side of a lumbar facet joint (right L3-4) and used to induce experimental low back pain for 10 min with continuous stimulation. Thresholds, stimulus-response relationships, distribution and quality of the electrically induced pain were recorded. Electrical facet joint stimulation induced low back pain and pain referral into the anterior leg, ipsilaterally, proximal to the knee, similar to what is observed clinically. Pressure pain thresholds did not change significantly before, during and after facet joint stimulation. In conclusion, we describe a novel model of acute experimental low back pain and demonstrate that generalized hyperalgesia did not develop within minutes of acute low back pain.

  14. Postural Responses to a Suddenly Released Pulling Force in Older Adults with Chronic Low Back Pain: An Experimental Study

    PubMed Central

    Lee, Pei-Yun; Lin, Sang-I; Liao, Yu-Ting; Lin, Ruey-Mo; Hsu, Che-Chia; Huang, Kuo-Yuan; Chen, Yi-Ting

    2016-01-01

    Chronic low back pain (CLBP), one of the most common musculoskeletal conditions in older adults, might affect balance and functional independence. The purpose of this study was to investigate the postural responses to a suddenly released pulling force in older adults with and without CLBP. Thirty community-dwelling older adults with CLBP and 26 voluntary controls without CLBP were enrolled. Participants were required to stand on a force platform while, with one hand, they pulled a string that was fastened at the other end to a 2-kg or to a 4-kg force in the opposite direction at a random order. The number of times the participants lost their balance and motions of center of pressure (COP) when the string was suddenly released were recorded. The results demonstrated that although the loss of balance rates for each pulling force condition did not differ between groups, older adults with CLBP had poorer postural responses: delayed reaction, larger displacement, higher velocity, longer path length, and greater COP sway area compared to the older controls. Furthermore, both groups showed larger postural responses in the 4-kg pulling force condition. Although aging is generally believed to be associated with declining balance and postural control, these findings highlight the effect of CLBP on reactive balance when responding to an externally generated force in an older population. This study also suggests that, for older adults with CLBP, in addition to treating them for pain and disability, reactive balance evaluation and training, such as reaction and movement strategy training should be included in their interventions. Clinicians and older patients with CLBP need to be made aware of the significance of impaired reactive balance and the increased risk of falls when encountering unexpected perturbations. PMID:27622646

  15. The Effects of Mindful Attention and State Mindfulness on Acute Experimental Pain Among Adolescents

    PubMed Central

    Chambers, Christine T.; Dick, Bruce D.

    2014-01-01

    Objective Attention-based coping strategies for pain are widely used in pediatric populations. The purpose of this study was to test a novel mindful attention manipulation on adolescent’s experimental pain responses. Furthermore, the relationship between state mindfulness and experimental pain was examined. Methods A total of 198 adolescents were randomly assigned to a mindful attention manipulation or control group prior to an experimental pain task. Participants completed measures of state mindfulness immediately prior to the pain task, and situational catastrophizing and pain intensity following the task. Results Overall the manipulation had no effect on pain. Secondary analysis showed that meditation experience moderated the effect of the manipulation. State mindfulness predicted pain outcomes, with reductions in situational catastrophizing mediating this relationship. Conclusions The mindful attention manipulation was effective among adolescents with a regular meditation practice. State mindfulness was related to ameliorated pain responses, and these effects were mediated by reduced catastrophizing. PMID:24599947

  16. The effects of patient-professional partnerships on the self-management and health outcomes for patients with chronic back pain: A quasi-experimental study.

    PubMed

    Fu, Yu; Yu, Ge; McNichol, Elaine; Marczewski, Kathryn; José Closs, S

    2016-07-01

    Self-management may be a lifelong task for patients with chronic back pain. Research suggests that chronic pain self-management programmes have beneficial effects on patients' health outcome. Contemporary pain management theories and models also suggest that a good patient-professional partnership enhances patients' ability to self-manage their condition. (1) To investigate whether there is a reciprocal relationship between self-management of chronic back pain and health-related quality of life (HRQoL); (2) to examine the impact of a good patient-professional partnership on HRQoL, either directly, or indirectly via change in the ability to self-manage pain. This quasi-experimental study was designed to take place during routine service appointments and conducted in a community-based pain management service in the United Kingdom. A patient-professional partnership was established in which patients were actively involved in setting up goals and developing individualised care plans. Through this, health professionals undertook patients' health needs assessment, collaborated with patients to identify specific problems, provided written materials and delivered individualised exercise based on patients' life situation. Patients were recruited following initial consultation and followed up three months later. A total of 147 patients (65% female) with a mean age of 48 years (standard deviation (SD): 14 years) were enrolled in the study. Of these, 103 subjects completed the study. Patients were included if they were aged 18 and over, suffered from chronic back pain, had opted in to the clinic and had sufficient ability to read and understand English. Patients were excluded if they opted out this service after the initial assessment, suffered from malignant pain or required acute medical interventions for their pain relief. Self-reported measures of HRQoL, patient-professional partnerships and self-management ability were collected at baseline and three months later

  17. Experimental Pain Phenotype Profiles in a Racially and Ethnically Diverse Sample of Healthy Adults

    PubMed Central

    Cruz-Almeida, Yenisel; Riley, Joseph L.; Fillingim, Roger B.

    2014-01-01

    Objective To examine patterns of interindividual variability in experimental pain responses emerging from multiple experimental pain measures in a racially/ethnically diverse sample of healthy adults and to examine the association between the derived phenotype profiles with demographic, psychological, and health-related measures. Methods Two hundred and ninety-one participants underwent heat, cold, pressure, and ischemic pain assessments, and completed several psychological and health-related assessments. The experimental pain measures were subjected to a principal component analysis and factor scores were used to compute Pain Sensitivity Index scores. The scores were subsequently submitted to a cluster analysis to identify patterns of pain sensitivity across experimental pain modalities. Results The sample was equally composed of non-Hispanic whites, African Americans, and Hispanic whites. Sensitivity scores were computed for heat pain, pressure pain, cold pain, ischemic pain, and temporal summation of heat pain. Five distinct clusters were characterized by high heat pain sensitivity, low ischemic pain sensitivity, low cold pain sensitivity, low pressure pain sensitivity, and high temporal summation. Cluster membership was significantly different by sex as well as somatic reactivity and catastrophizing, although cluster differences were most pronounced between the heat pain-sensitive individuals vs the cold pain-insensitive individuals. Conclusions Our findings highlight the importance of phenotyping individuals to account for interindividual differences in pain responses. Our findings also replicate previously reported pain phenotypes, which are not solely related to demographic, psychosocial, or health-related factors in our healthy participants. Future studies designed to elucidate the biological underpinnings of pain sensitivity profiles would be of substantial value. PMID:23889771

  18. The Effect of Intrathecal Administration of Muscimol on Modulation of Neuropathic Pain Symptoms Resulting from Spinal Cord Injury; an Experimental Study

    PubMed Central

    Hosseini, Marjan; Karami, Zohreh; Janzadenh, Atousa; Jameie, Seyed Behnamedin; Haji Mashhadi, Zahra; Yousefifard, Mahmoud; Nasirinezhad, Farinaz

    2014-01-01

    Introduction: Neuropathic pain can be very difficult to treat and it is one of the important medical challenging about pain treatments. Muscimol as a new agonist of gamma-Aminobutyric acid receptor type A (GABAA) have been introduced for pain management. Thus, the present study was performed to evaluate the pain alleviating effect of intrathecal injection of different doses of muscimol as GABAA receptor agonist in spinal cord injury (SCI) model of neuropathic pain. Methods: In the present experimental study, male Wistar rats were treated by muscimol 0.01, 0.1 or 1 µg/10ul, intrathecally (i.t.) three weeks after induction of spinal cord injury using compression injury model. Neuropathic pain symptoms were assessed at before treatment, 15 minutes, one hour and three hours after muscimol administration. The time of peak effect and optimum dosage was assessed by repeated measures analysis of variance and analysis of covariance, respectively. Results: Muscimol with the dose of 0.01 µg in 15 minutes caused to improve the thermal hyperalgesia (df: 24, 5; F= 6.6; p<0.001), mechanical hyperalgesia (df: 24, 5; F= 7.8; p<0.001), cold allodynia (df: 24, 5; F= 6.96; p<0.001), and mechanical allodynia (df: 24, 5; F= 15.7; p<0.001). The effect of doses of 0.1 µg and 1 µg were also significant. In addition, the efficacy of different doses of muscimol did not have difference on thermal hyperalgesia (df: 24, 5; F= 1.52; p= 0.24), mechanical hyperalgesia (df: 24, 5; F= 0.3; p= -0.75), cold allodynia (df: 24, 5; F= 0.8; p= -0.56), and mechanical allodynia (df: 24, 5; F= 1.75; p= 0.86). Conclusion: The finding of the present study revealed that using muscimol with doses of 0.01µg, 0.1µg, and 1 µg reduces the symptoms of neuropathic pain. In addition, the effect of GABAA agonist is short term and its effectiveness gradually decreases by time. PMID:26495371

  19. An experimental study on the effectiveness of massage with aromatic ginger and orange essential oil for moderate-to-severe knee pain among the elderly in Hong Kong.

    PubMed

    Yip, Yin Bing; Tam, Ada Chung Ying

    2008-06-01

    To assess the efficacy of an aromatic essential oil (1% Zingiber officinale and 0.5% Citrus sinesis) massage among the elderly with moderate-to-severe knee pain. Fifty-nine older persons were enrolled in a double-blind, placebo-controlled experimental study group from the Community Centre for Senior Citizens, Hong Kong. The intervention was six massage sessions with ginger and orange oil over a 3-week period. The placebo control group received the same massage intervention with olive oil only and the control group received no massage. Assessment was done at baseline, post 1-week and post 4 weeks after treatment. Changes from baseline to the end of treatment were assessed on knee pain intensity, stiffness level and physical functioning (by Western Ontario and McMaster Universities Osteoarthritis index) and quality of life (by SF-36). There were significant mean changes between the three time-points within the intervention group on three of the outcome measures: knee pain intensity (p=0.02); stiffness level (p=0.03); and enhancing physical function (p=0.04) but these were not apparent with the between-groups comparison (p=0.48, 0.14 and 0.45 respectively) 4 weeks after the massage. The improvement of physical function and pain were superior in the intervention group compared with both the placebo and the control group at post 1-week time (both p=0.03) but not sustained at post 4 weeks (p=0.45 and 0.29). The changes in quality of life were not statistically significant for all three groups. The aroma-massage therapy seems to have potential as an alternative method for short-term knee pain relief.

  20. Tailored skills training for practitioners to enhance assessment of prognostic factors for persistent and disabling back pain: four quasi-experimental single-subject studies.

    PubMed

    Demmelmaier, Ingrid; Denison, Eva; Lindberg, Per; Åsenlöf, Pernilla

    2012-07-01

    The well-known gap between guidelines and behaviour in clinical practice calls for effective behaviour change interventions. One example showing this gap is physiotherapists' insufficient assessment of psychosocial prognostic factors in back pain (i.e., yellow flags). The present study aimed to evaluate an educational model by performing a tailored skills training intervention for caregivers and studying changes over time in physiotherapists' assessment of prognostic factors in telephone consultations. A quasi-experimental single-subject design over 36 weeks was used, with repeated measurements during baseline, intervention, and postintervention phases. Four physiotherapists in primary health care audiorecorded a total of 63 consultations with patients. The tailored intervention included individual goal setting, skills training, and feedback on performance. The primary outcome was the number of assessed prognostic factors (0-10). Changes were seen in all four participants. The amount of assessed prognostic factors increased from between 0 and 2 at baseline to between 6 and 10 at postintervention. Time spent on assessment of psychosocial factors increased, and time spent on discussions about biomedical pain symptoms decreased. Knowledge and biopsychosocial attitudes toward back pain were congruent with guidelines at inclusion and did not change markedly during the intervention. Self-efficacy for assessment of cognitive and emotional prognostic factors increased during the study phases. The results suggest that a tailored skills training intervention using behaviour change techniques, such as individual goal setting, skills training, and feedback on performance, is effective in producing change in specific clinical behaviours in physiotherapists.

  1. Ketoprofen Dental Pain Study.

    PubMed

    Levin, L M; Cooper, S A; Betts, N J; Wedell, D; Hermann, D G; Lamp, C; Secreto, S A; Hersh, E V

    1997-01-01

    Ketoprofen is a nonsteroidal antiinflammatory drug, recently approved as an over-the-counter (OTC) analgesic at a 12.5 mg dosage strength. This is the first published study which explores the analgesic efficacy and safety of ketoprofen 12.5 mg in patients experiencing pain following the removal of impacted third molars. This study was single-dose, double-blind and randomized utilizing a 6-hour in-patient evaluation period. Patients ingested a single dose of ketoprofen 12.5 mg (n = 30), ketoprofen 37.5 mg (n = 32) or placebo (n = 15) when their post-surgical pain reached at least a moderate intensity on a 5-point categorical (CAT) scale and greater than 50 mm on a 100 mm visual analog scale (VAS). Measures of pain intensity and relief were gathered every 20 minutes for the first 2 hours, and then hourly from hours 3 through 6. Adverse drug reactions were also recorded as they occurred. Both dosages of ketoprofen were significantly more efficacious than placebo (two way ANOVAs, p < 0.05). For pain intensity difference (PID) and pain relief, the 12.5 mg dose exhibited statistical superiority from hours 1 through 3, while the 37.5 mg dose exhibited statistical superiority from 40 minutes through 4 hours. Ketoprofen 37.5 mg was significantly more efficacious than the 12.5 mg dose only at 40 minutes for PID(VAS) and relief, and at 60 minutes for PID(VAS). Both ketoprofen dosages displayed significantly greater 3-hr, 4-hr and 6-hr summary analgesic measures (SPID(VAS), SPID(CAT), TOTPAR) than placebo, with the exception of the 6-hr SPID(CAT) measure for ketoprofen 12.5 mg. No serious side effects were observed in this study. We conclude that ketoprofen in a dose range of 12.5 mg to 37.5 mg is a safe and effective analgesic for the relief of post-operative dental pain.

  2. Hypoalgesic effect of caffeine in experimental ischemic muscle contraction pain.

    PubMed

    Myers, D E; Shaikh, Z; Zullo, T G

    1997-01-01

    It has been theorized that adenosine is a leading candidate for the metabolite responsible for ischemic muscle pain. The purpose of this study was to determine the effect of the non-selective adenosine receptor antagonist, caffeine, on ischemic skeletal muscle contraction pain. Seven healthy adult volunteers with no history of pain disorders, systemic disease, or habitual caffeine use, were chosen for the two-session, cross-over, double-blind study. Every subject received either 200 mg of caffeine (NoDoz, Bristol-Myers) or identical placebo 1 hour before each of the two trials. Ischemia of the forearm was achieved by inflation of a blood pressure cuff to 250 mm Hg. Forearm muscle activity was generated by performance of wrist curis using a 5-gram bar at a rate of 40 cycles per minute. Pain was rated at 15-second intervals for 1 minute using a visual analog scale (0 to 10) with verbal descriptors. Significance was determined by univariate and multivariate analyses of variance and covariance including repeated measures. Pain ratings at 15 seconds in the caffeine trial were significantly lower (P < 0.02) than those in the placebo trial. This effect continued at 30 seconds (P < 0.05). However, by 45 seconds, pain in the caffeine trial was not significantly lower (P = 0.4) than that in the placebo trial. These results show that high-dose caffeine exhibits considerable analgesic efficacy in experimental muscle pain, adding support for a role of adenosine in producing ischemic muscle contraction pain.

  3. Pain perception in people with Down syndrome: a synthesis of clinical and experimental research

    PubMed Central

    McGuire, Brian E.; Defrin, Ruth

    2015-01-01

    People with an intellectual disability experience both acute and chronic pain with at least the same frequency as the general population. However, considerably less is known about the pain perception of people with Down syndrome. In this review paper, we evaluated the available clinical and experimental evidence. Some experimental studies of acute pain have indicated that pain threshold was higher than normal but only when using a reaction time method to measure pain sensitivity. However, when reaction time is not part of the calculation of the pain threshold, pain sensitivity in people with Down syndrome is in fact lower than normal (more sensitive to pain). Clinical studies of chronic pain have shown that people with an intellectual disability experience chronic pain and within that population, people with Down syndrome also experience chronic pain, but the precise prevalence of chronic pain in Down syndrome has yet to be established. Taken together, the literature suggests that people with Down syndrome experience pain, both acute and chronic, with at least the same frequency as the rest of the population. Furthermore, the evidence suggests that although acute pain expression appears to be delayed, once pain is registered, there appears to be a magnified pain response. We conclude by proposing an agenda for future research in this area. PMID:26283936

  4. Alterations in endogenous pain modulation in endurance athletes: an experimental study using quantitative sensory testing and the cold-pressor task.

    PubMed

    Tesarz, Jonas; Gerhardt, Andreas; Schommer, Kai; Treede, Rolf-Detlef; Eich, Wolfgang

    2013-07-01

    There is evidence for long-term alterations in pain tolerance among athletes compared with normally active controls. However, scientific data on pain thresholds in this population are inconsistent, and the underlying mechanisms for the differences remain unclear. Therefore, we assessed differences and similarities in pain perception and conditioned pain modulation (CPM) at rest in endurance athletes and normally active controls. The standardised quantitative sensory testing protocol (QST) of the 'German-Research-Network-on-Neuropathic-Pain' was used to obtain comprehensive profiles on somatosensory functions. The protocol consisted of thermal and mechanical detection as well as pain thresholds, vibration thresholds, and pain sensitivity to sharp and blunt mechanical stimuli. CPM (the diffuse-noxious-inhibitory-control-like effect) was measured using 2 tonic heat pain test stimuli (at the temperature exceeding a subjective pain rating of 50/100) separated by a 2-min cold-pressor task (CPM-TASK; conditioning stimulus). Pain ratings were measured with a numerical rating scale. Endurance capacity was validated by assessment of maximum oxygen uptake (VO2max). Participants included 25 pain-free male endurance athletes (VO2max>60mL/min∗kg) and 26 pain-free normally active controls (VO2max<45mL/min∗kg) matched based on age and body mass index. Athletes were significantly less sensitive to mechanical pain but showed higher sensitivity to vibration (P<0.05). In athletes, CPM was significantly less activated by the conditioning stimuli (P<0.05) when compared with normally active controls. Our data show that somatosensory processing in athletes differs in comparison with controls, and suggest that the endogenous pain inhibitory system may be less responsive. This finding may explain the paradoxical propensity of athletes to develop chronic widespread pain. Copyright © 2013 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

  5. Experimental pain responses in children with chronic pain and in healthy children: How do they differ?

    PubMed Central

    Tsao, Jennie CI; Evans, Subhadra; Seidman, Laura C; Zeltzer, Lonnie K

    2012-01-01

    BACKGROUND: Extant research comparing laboratory pain responses of children with chronic pain with healthy controls is mixed, with some studies indicating lower pain responsivity for controls and others showing no differences. Few studies have included different pain modalities or assessment protocols. OBJECTIVES: To compare pain responses among 26 children (18 girls) with chronic pain and matched controls (mean age 14.8 years), to laboratory tasks involving thermal heat, pressure and cold pain. Responses to cold pain were assessed using two different protocols: an initial trial of unspecified duration and a second trial of specified duration. METHODS: Four trials of pressure pain and of thermal heat pain stimuli, all of unspecified duration, were administered, as well as the two cold pain trials. Heart rate and blood pressure were assessed at baseline and after completion of the pain tasks. RESULTS: Pain tolerance and pain intensity did not differ between children with chronic pain and controls for the unspecified trials. For the specified cold pressor trial, 92% of children with chronic pain completed the entire trial compared with only 61.5% of controls. Children with chronic pain exhibited a trend toward higher baseline and postsession heart rate and reported more anxiety and depression symptoms compared with control children. CONCLUSIONS: Contextual factors related to the fixed trial may have exerted a greater influence on pain tolerance in children with chronic pain relative to controls. Children with chronic pain demonstrated a tendency toward increased arousal in anticipation of and following pain induction compared with controls. PMID:22518373

  6. Effects of intrathecal ketorolac on human experimental pain

    PubMed Central

    Eisenach, James C.; Curry, Regina; Tong, Chuanyao; Houle, Timothy T.; Yaksh, Tony L.

    2010-01-01

    Background Nonsteroidal antiinflammatory drugs, the most commonly used analgesics, reduce pain by inhibiting cyclooxygenase at peripheral sites of inflammation, but potentially also by inhibiting cyclooxygenase in the central nervous system, especially the spinal cord. Animal studies suggest that products of cyclooxygenase in the spinal cord do not alter pain responses to acute noxious stimuli, but reduce pain and sensitization following peripheral inflammation. We used spinal injection of small doses of the cyclooxygenase inhibitor, ketorolac, to survey the role of spinal cyclooxygenase in human experimental pain and hypersensitivity states. Methods Following regulatory agency approval and informed consent, we examined the effect of 2.0 mg intrathecal ketorolac in 41 healthy volunteers to acute noxious thermal stimuli in normal skin and to mechanical stimuli in skin sensitized by topical capsaicin or ultraviolet burn. We also examined the effect of intravenous ketorolac, Results Intrathecal ketorolac reduced hypersensitivity when it was induced by a combination of ultraviolet burn plus intermittent heat and, according to one of two analytical strategies, when it was induced by ultraviolet burn alone. Conclusions These data suggest a more limited role for spinal cord cyclooxygenase in human pain states than predicted by studies in animals. PMID:20395821

  7. Intravenous caffeine citrate vs. magnesium sulfate for reducing pain in patients with acute migraine headache; a prospective quasi-experimental study.

    PubMed

    Baratloo, Alireza; Mirbaha, Sahar; Delavar Kasmaei, Hossein; Payandemehr, Pooya; Elmaraezy, Ahmed; Negida, Ahmed

    2017-07-01

    Current evidence suggests that intravenous magnesium sulfate might be effective for reducing migraine pain. In a recent pilot study, we showed that intravenous caffeine citrate could reduce the severity of migraine headache. The objective of this study is to investigate the efficacy of intravenous caffeine citrate vs. magnesium sulfate for management of acute migraine headache. We conducted a prospective quasi-experimental study from January until May 2016 in two educational medical centers of Shahid Beheshti University of Medical Sciences (Shoahadaye Tajrish Hospital and Imam Hossein Hospital), Tehran, Iran. The study included patients who were referred to the emergency department and met the migraine diagnosis criteria of the International Headache Society. Patients were allocated into 2 groups receiving either 60 mg intravenous caffeine or 2 g intravenous magnesium sulfate. The pain scores, based on the visual analog scale, were recorded on admission, as well as one and two hours after receiving the drug. A Chi-Square test and student t-test were used for analysis of baseline characteristics. A Mann-Whitney U test and Wilcoxon singed rank test were used to analyze differences in the visual analogue scale (VAS) score between and within the groups respectively. In total, 70 patients (35 patients in each group) with the mean age of 33.1 ± 11.3 years were included (64.3% female). For the Caffeine citrate group, the median pain score decreased from 9.0 (2.0) to 5.0 (4.0) after one hour and to 3.0 (4.0) after two hours. For the magnesium sulfate group, the pain score decreased from 8.0 (2.0) to 2.0 (2.0) after one hour and to 0.0 (1.0) after two hours. Both intravenous caffeine citrate and intravenous magnesium sulfate reduced pain scores significantly but the magnesium sulfate group showed more improvement than the Caffeine citrate group after one hour (P < 0.001) and after two hours (P < 0.001). It is likely that both intravenous caffeine and intravenous magnesium

  8. Sex differences in experimental pain among healthy children: a systematic review and meta-analysis.

    PubMed

    Boerner, Katelynn E; Birnie, Kathryn A; Caes, Line; Schinkel, Meghan; Chambers, Christine T

    2014-05-01

    Sex differences in response to experimental pain are commonly reported in systematic reviews in the adult literature. The objective of the present research was to conduct a systematic review and meta-analysis of sex differences in healthy children's responses to experimental pain (e.g., cold pressor, heat pain, pressure pain) and, where possible, to conduct analyses separately for children and adolescents. A search was conducted of electronic databases for published papers in English of empirical research using experimental pain tasks to examine pain-related outcomes in healthy boys and girls between 0 and 18 years of age. Eighty articles were eligible for inclusion and were coded to extract information relevant to sex differences. The systematic review indicated that, across different experimental pain tasks, the majority of studies reported no significant differences between boys and girls on pain-related outcomes. However, the meta-analysis of available combined data found that girls reported significantly higher cold pressor pain intensity compared to boys in studies where the mean age of participants was greater than 12 years. Additionally, a meta-analysis of heat pain found that boys had significantly higher tolerance than girls overall, and boys had significantly higher heat pain threshold than girls in studies where the mean age of participants was 12 years or younger. These findings suggest that developmental stage may be relevant for understanding sex differences in pain.

  9. Nonverbal Communication as a Pain Reliever: The Impact of Physician Supportive Nonverbal Behavior on Experimentally Induced Pain.

    PubMed

    Ruben, Mollie A; Blanch-Hartigan, Danielle; Hall, Judith A

    2017-08-01

    Despite the evidence for the potential of supportive communication to alleviate physical pain, no study to date has assessed the impact of supportive nonverbal behavior on the objective and subjective experience of pain. This analogue study examined the impact of an actor-physician's supportive nonverbal behavior on experimentally induced pain. Participants (N = 205) were randomly assigned to interact with a videotaped physician conveying high or low supportive nonverbal behaviors. Participant pain was assessed with subjective and objective measures. Participants interacting with the high nonverbal support physicians showed increased pain tolerance and a reduction in the amount of pain expressed compared to those interacting with the low nonverbal support physicians. For subjectively rated pain, a gender difference existed such that for men, high physician nonverbal support decreased pain ratings and memory of pain, but for women, high physician nonverbal support increased pain ratings and memory of pain. These results highlight the importance of nonverbal communication in altering pain with broad implications for clinical care.

  10. Transcranial direct current stimulation over the opercular somatosensory region does not influence experimentally induced pain: a triple blind, sham-controlled study

    PubMed Central

    Koyama, Soichiro; Nakagawa, Kei

    2017-01-01

    Transcranial magnetic stimulation (TMS) over the opercular somatosensory region (OP), which includes the secondary somatosensory cortex and the insular cortex, suppresses pain sensation. However, whether transcranial direct current stimulation (tDCS) over the OP has a similar effect on pain sensation remains unknown. We examined whether pain sensation would be suppressed by tDCS over the OP. Our experiment with a triple-blind, sham-controlled, crossover design involved 12 healthy participants. Participants were asked to rate their subjective pain intensity during and after three types of bihemispheric tDCS: right anodal/left cathodal OP tDCS, left anodal/right cathodal OP tDCS (2 mA, 12 min), and sham tDCS (15 s). Pain stimuli were alternately applied to the dorsum of each index finger using intraepidermal electrical stimulation. We observed no significant effect of tDCS over the OP on the perception of experimentally induced pain. Subjective pain intensity did not differ significantly between the three tDCS conditions. The present null results have crucial implications for the selection of optimal stimulation regions and parameters for clinical pain treatment. PMID:27984542

  11. Human experimental pain models: A review of standardized methods in drug development

    PubMed Central

    Reddy, K. Sunil kumar; Naidu, M. U. R.; Rani, P. Usha; Rao, T. Ramesh Kumar

    2012-01-01

    Human experimental pain models are essential in understanding the pain mechanisms and appear to be ideally suited to test analgesic compounds. The challenge that confronts both the clinician and the scientist is to match specific treatments to different pain-generating mechanisms and hence reach a pain treatment tailored to each individual patient. Experimental pain models offer the possibility to explore the pain system under controlled settings. Standardized stimuli of different modalities (i.e., mechanical, thermal, electrical, or chemical) can be applied to the skin, muscles, and viscera for a differentiated and comprehensive assessment of various pain pathways and mechanisms. Using a multimodel-multistructure testing, the nociception arising from different body structures can be explored and modulation of specific biomarkers by new and existing analgesic drugs can be profiled. The value of human experimental pain models is to link animal and clinical pain studies, providing new possibilities for designing successful clinical trials. Spontaneous pain, the main compliant of the neuropathic patients, but currently there is no human model available that would mimic chronic pain. Therefore, current human pain models cannot replace patient studies for studying efficacy of analgesic compounds, although being helpful for proof-of-concept studies and dose finding. PMID:23626642

  12. Ethnic Identity Predicts Experimental Pain Sensitivity In African Americans and Hispanics

    PubMed Central

    Rahim-Williams, F. Bridgett; Riley, Joseph L.; Herrera, Dyanne; Campbell, Claudia; Hastie, Barbara A.; Fillingim, Roger B.

    2007-01-01

    The aim of this study was to examine experimental pain sensitivity in three ethnic groups, African Americans, Hispanic Americans and non-Hispanic whites, and to determine whether ethnic identity is differentially associated with pain sensitivity across ethnic groups. Participants included sixty-three African American, sixty-one Hispanic and eighty-two non-Hispanic white participants who were assessed using three experimental pain measures: thermal, cold-pressor and ischemic. Participants’ ethnic identity was assessed using the Multi-group Ethnic Identity Measure (MEIM). Ethnic group differences in pain responses were observed, with African American and Hispanic subjects showing lower cold and heat pain tolerances than non-Hispanic whites. In addition, pain range (i.e. tolerance – threshold) was computed for heat, cold and ischemic pain, and the two minority groups again had lower values compared to non-Hispanic whites. Ethnic identity was associated with pain range only for African American and Hispanic groups. Statistically controlling for ethnic identity rendered some of the group differences in pain range non-significant. These findings indicate that ethnic identity is associated with pain sensitivity in ethnic minority groups, and may partially mediate group differences in pain perception. The results of the present investigation provide evidence of ethnic group differences in responses to experimental pain across multiple noxious stimuli, with both minority groups exhibiting greater sensitivity to laboratory evoked pain compared to non-Hispanic whites. PMID:17296267

  13. Experimental reduction of pain catastrophizing modulates pain report but not spinal nociception as verified by mediation analyses.

    PubMed

    Terry, Ellen L; Thompson, Kathryn A; Rhudy, Jamie L

    2015-08-01

    Pain catastrophizing is associated with enhanced pain; however, the mechanisms by which it modulates pain are poorly understood. Evidence suggests that catastrophizing modulates supraspinal processing of pain but does not modulate spinal nociception (as assessed by nociceptive flexion reflex [NFR]). Unfortunately, most NFR studies have been correlational. To address this, this study experimentally reduced catastrophizing to determine whether it modulates spinal nociception (NFR). Healthy pain-free participants (N = 113) were randomly assigned to a brief 30-minute catastrophizing reduction manipulation or a control group that received pain education. Before and after manipulations, 2 types of painful stimuli were delivered to elicit (1) NFR (single trains of stimuli) and (2) temporal summation of NFR (3 stimulations at 2 Hz). After each set of stimuli, participants were asked to report their pain intensity and unpleasantness, as well as their situation-specific catastrophizing. Manipulation checks verified that catastrophizing was effectively reduced. Furthermore, pain intensity and unpleasantness to both stimulation types were reduced by the catastrophizing manipulation, effects that were mediated by catastrophizing. Although NFRs were not affected by the catastrophizing manipulation, temporal summation of NFR was reduced. However, this effect was not mediated by catastrophizing. These results indicate that reductions in catastrophizing lead to reductions in pain perception but do not modulate spinal nociception and provides further evidence that catastrophizing modulates pain at the supraspinal, not the spinal, level.

  14. The role of experimentally-induced subacromial pain on shoulder strength and throwing accuracy.

    PubMed

    Wassinger, Craig A; Sole, Gisela; Osborne, Hamish

    2012-10-01

    Shoulder injuries often comprise two separate yet related components, structural tissue damage and pain. The role of each of these components on shoulder function is difficult to ascertain. Experimental pain models allow the assessment of consequences of localized pain when applied to healthy individuals. By understanding the role of pain on shoulder function, clinicians will be able to more efficiently assess and treat shoulder injuries. The objective of the study was to evaluate the role of experimentally-induced sub-acromial pain on shoulder isokinetic rotational strength and throwing accuracy. This was a block counterbalanced, crossover, repeated measures study design utilizing 20 individuals without self-reported shoulder or cervical pathology. Shoulder function was measured with and without experimental pain injection (2 mL of 5% hypertonic saline) in the sub-acromial space. Functional tasks consisted of shoulder rotational strength utilizing isokinetic testing and throwing accuracy via the functional throwing performance index. The hypertonic saline induced moderate pain levels in all participants (4.3-5.1/10). Normalized shoulder internal (t = 3.76, p = 0.001) and external (t = 3.12, p = 0.006) rotation strength were both diminished in the painful condition compared to the pain free condition. Throwing accuracy was also reduced while the participants experienced pain (t = 3.99, p = 0.001). Moderate levels of experimental shoulder pain were sufficient to negatively influence shoulder strength and throwing accuracy in participants without shoulder pathology.

  15. Pain modulatory phenotypes differentiate subgroups with different clinical and experimental pain sensitivity.

    PubMed

    Vaegter, Henrik B; Graven-Nielsen, Thomas

    2016-07-01

    Pain biomarkers are warranted for individualized pain management. Based on different pain modulatory phenotypes, the objectives of this study were to explore the existence of subgroups within patients with nonmalignant chronic pain and to investigate differences in clinical pain and pain hypersensitivity between subgroups. Cuff algometry was performed on lower legs in 400 patients with chronic pain to assess pressure pain threshold, pressure pain tolerance, temporal summation of pain (TSP: increase in pain scores to 10 repeated stimulations), and conditioned pain modulation (CPM: increase in cuff pressure pain threshold during cuff pain conditioning on the contralateral leg). Heat detection and heat pain thresholds at clinical painful and nonpainful body areas were assessed. Based on TSP and CPM, 4 distinct groups were formed: group 1 (n = 85) had impaired CPM and facilitated TSP; group 2 (n = 148) had impaired CPM and normal TSP; group 3 (n = 45) had normal CPM and facilitated TSP; and group 4 (n = 122) had normal CPM and normal TSP. Group 1 showed more pain regions than the other 3 groups (P < 0.001), indicating that impaired CPM and facilitated TSP play an important role in widespread pain. Groups 1 and 2 compared with group 4 had lower heat pain threshold at nonpainful areas and lower cuff pressure pain tolerance (P < 0.02), indicating that CPM plays a role for widespread hyperalgesia. Moreover, group 1 demonstrated higher clinical pain scores than group 4 (P < 0.05). Although not different between subgroups, patients were profiled on demographics, disability, pain catastrophizing, and fear of movement. Future research should investigate interventions tailored towards these subgroups.

  16. Long-Term Effects of Interprofessional Biopsychosocial Rehabilitation for Adults with Chronic Non-Specific Low Back Pain: A Multicentre, Quasi-Experimental Study

    PubMed Central

    Semrau, Jana; Hentschke, Christian; Buchmann, Jana; Meng, Karin; Vogel, Heiner; Faller, Hermann; Bork, Hartmut; Pfeifer, Klaus

    2015-01-01

    Background Improvement of the long-term effectiveness of multidisciplinary ortho-paedic rehabilitation (MOR) in the management of chronic non-specific low back pain (CLBP) remains a central issue for health care in Germany. We developed an interprofessional and interdisciplinary, biopsychosocial rehabilitation concept named “PASTOR” to promote self-management in adults with CLBP and compared its effectiveness with the current model of MOR. Methods A multicentre quasi-experimental study with three measurement time points was implemented. 680 adults aged 18 to 65 with CLBP were assed for eligibil-ity in three inpatient rehabilitation centres in Germany. At first the effects of the MOR, with a total extent of 48 hours (control group), were assessed. Thereafter, PASTOR was implemented and evaluated in the same centres (intervention group). It consisted of six interprofessional modules, which were provided on 12 days in fixed groups, with a total extent of 48 hours. Participants were assessed with self-report measures at baseline, discharge, and 12 months for functional ability (primary outcome) using the Hannover Functional Ability Questionnaire (FFbH-R) and vari-ous secondary outcomes (e.g. pain, health status, physical activity, pain coping, pain-related cognitions). Results In total 536 participants were consecutively assigned to PASTOR (n=266) or MOR (n=270). At 12 months, complete data of 368 participants was available. The adjusted between-group difference in the FFbH-R at 12 months was 6.58 (95% CI 3.38 to 9.78) using complete data and 3.56 (95% CI 0.45 to 6.67) using available da-ta, corresponding to significant small-to-medium effect sizes of d=0.42 (p<0.001) and d=0.10 (p=0.025) in favour of PASTOR. Further improvements in secondary out-comes were also observed in favour of PASTOR. Conclusion The interprofessional and interdisciplinary, biopsychosocial rehabilita-tion program PASTOR shows some improvements of the long-term effectiveness of inpatient

  17. Experimental neck muscle pain impairs standing balance in humans.

    PubMed

    Vuillerme, Nicolas; Pinsault, Nicolas

    2009-02-01

    Impaired postural control has been reported in patients with chronic neck pain of both traumatic and non-traumatic etiologies, but whether painful stimulation of neck muscle per se can affect balance control during quiet standing in humans remains unclear. The purpose of the present experiment was thus to investigate the effect of experimental neck muscle pain on standing balance in young healthy adults. To achieve this goal, 16 male university students were asked to stand upright as still as possible on a force platform with their eyes closed in two conditions of No pain and Pain of the neck muscles elicited by experimental painful electrical stimulation. Postural control and postural performance were assessed by the displacements of the center of foot pressure (CoP) and of the center of mass (CoM), respectively. The results showed increased CoP and CoM displacements variance, range, mean velocity, and mean and median frequencies in the Pain relative to the No pain condition. The present findings emphasize the destabilizing effect of experimental neck muscle pain per se, and more largely stress the importance of intact neck neuromuscular function on standing balance.

  18. Gender, variation in opioid receptor genes and sensitivity to experimental pain

    PubMed Central

    2013-01-01

    Background Pain tolerance is subject to considerable inter-individual variation, which may be influenced by a number of genetic and non-genetic factors. The mu, delta and kappa opioid receptors play a role in pain perception and are thought to mediate different pain modalities. The aim of this study was to explore associations between pain thresholds and gender and genetic variants in the three opioid receptor genes (OPRM, OPRD and OPRK). Experimental multi-modal pain data from previously published studies carried out in healthy Caucasian volunteers were used in order to limit the number of confounders to the study outcome. Data on thermal skin pain (n=36), muscle pressure pain (n=31) and mechanical visceral pain (n=50)) tolerance thresholds were included. Results Nineteen genetic polymorphisms were included in linear regression modeling. Males were found to tolerate higher thermal and muscle pressure pain than females (p=0.003 and 0.02). Thirty four percent of variability in thermal skin pain was accounted for by a model consisting of OPRK rs6473799 and gender. This finding was just outside significance when correction for multiple testing was applied. Variability in muscle pressure pain tolerance was associated with OPRK rs7016778 and rs7824175. These SNPs accounted for 43% of variability in muscle pressure pain sensitivity and these findings remained significant after adjustment for multiple testing. No association was found with mechanical visceral pain. Conclusion This is a preliminary and hypothesis generating study due to the relatively small study size. However, significant association between the opioid receptor genes and experimental pain sensitivity supports the influence of genetic variability in pain perception. These findings may be used to generate hypotheses for testing in larger clinical trials of patients with painful conditions. PMID:23570317

  19. Experimental knee pain impairs submaximal force steadiness in isometric, eccentric, and concentric muscle actions.

    PubMed

    Rice, David A; McNair, Peter J; Lewis, Gwyn N; Mannion, Jamie

    2015-09-12

    Populations with knee joint damage, including arthritis, have noted impairments in the regulation of submaximal muscle force. It is difficult to determine the exact cause of such impairments given the joint pathology and associated neuromuscular adaptations. Experimental pain models that have been used to isolate the effects of pain on muscle force regulation have shown impaired force steadiness during acute pain. However, few studies have examined force regulation during dynamic contractions, and these findings have been inconsistent. The goal of the current study was to examine the effect of experimental knee joint pain on submaximal quadriceps force regulation during isometric and dynamic contractions. The study involved fifteen healthy participants. Participants were seated in an isokinetic dynamometer. Knee extensor force matching tasks were completed in isometric, eccentric, and concentric muscle contraction conditions. The target force was set to 10 % of maximum for each contraction type. Hypertonic saline was then injected into the infrapatella fat pad to generate acute joint pain. The force matching tasks were repeated during pain and once more 5 min after pain had subsided. Hypertonic saline resulted in knee pain with an average peak pain rating of 5.5 ± 2.1 (0-10 scale) that lasted for 18 ± 4 mins. Force steadiness significantly reduced during pain across all three muscle contraction conditions. There was a trend to increased force matching error during pain but this was not significant. Experimental knee pain leads to impaired quadriceps force steadiness during isometric, eccentric, and concentric contractions, providing further evidence that joint pain directly affects motor performance. Given the established relationship between submaximal muscle force steadiness and function, such an effect may be detrimental to the performance of tasks in daily life. In order to restore motor performance in people with painful arthritic conditions of the

  20. Cortical representation of experimental tooth pain in humans.

    PubMed

    Jantsch, H H F; Kemppainen, P; Ringler, R; Handwerker, H O; Forster, C

    2005-12-05

    Cortical processing of electrically induced pain from the tooth pulp was studied in healthy volunteers with fMRI. In a first experiment, cortical representation of tooth pain was compared with that of painful mechanical stimulation to the hand. The contralateral S1 cortex was activated during painful mechanical stimulation of the hand, whereas tooth pain lead to bilateral activation of S1. The S2 and insular region were bilaterally activated by both stimuli. In S2, the center of gravity of the activation during painful mechanical stimulation was more medial/posterior compared to tooth pain. In the insular region, tooth pain induced a stronger activation of the anterior and medial parts. The posterior part of the anterior cingulate gyrus was more strongly activated by painful stimulation of the hand. Differential activations were also found in motor and frontal areas including the orbital frontal cortex where tooth pain lead to greater activations. In a second experiment, we compared the effect of weak with strong tooth pain. A significantly greater activation by more painful tooth stimuli was found in most of those areas in which tooth pain had induced more activation than hand pain. In the medial frontal and right superior frontal gyri, we found an inverse relationship between pain intensity and BOLD contrast. We concluded that tooth pain activates a cortical network which is in several respects different from that activated by painful mechanical stimulation of the hand, not only in the somatotopically organized somatosensory areas but also in parts of the 'medial' pain projection system.

  1. In Vivo praying and catastrophizing mediate the race differences in experimental pain sensitivity.

    PubMed

    Meints, Samantha M; Hirsh, Adam T

    2015-05-01

    Black individuals have a lower tolerance for experimental pain than white individuals. Black and white individuals also differ in their use of pain coping strategies, which may explain the race differences in pain sensitivity. We examined the extent to which situation-specific pain coping mediated black-white differences in pain sensitivity. We hypothesized that 1) black participants would demonstrate lower pain tolerance than white participants, 2) black participants would use different pain coping strategies than white participants, and 3) the differential use of these strategies would mediate the relationship between race and pain tolerance. Healthy college undergraduates (N = 190) participated in a cold pressor task and then completed the Coping Strategies Questionnaire-Revised to assess their situation-specific pain coping. Compared with white participants, black participants demonstrated lower pain tolerance, engaged in more situation-specific catastrophizing and praying, and ignored pain less frequently. Catastrophizing and praying were inversely related to pain tolerance and were significant mediators of the relationship between race and pain tolerance. The indirect effect of praying was stronger than that of catastrophizing. Race differences in pain sensitivity may be due, in part, to differences in the use of catastrophizing and praying as coping strategies. These results may help guide treatments addressing maladaptive pain coping. This study suggests that race differences in pain sensitivity may be due, in part, to the differential use of catastrophizing and praying strategies. Psychosocial treatments for pain should encourage patients to take an active role in their pain management. Copyright © 2015 American Pain Society. Published by Elsevier Inc. All rights reserved.

  2. Effects of a Pain Catastrophizing Induction on Sensory Testing in Women with Chronic Low Back Pain: A Pilot Study

    PubMed Central

    Sturgeon, John A.; Johnson, Kevin A.

    2017-01-01

    Pain catastrophizing, a pattern of negative cognitive-emotional responses to actual or anticipated pain, maintains chronic pain and undermines response to treatments. Currently, precisely how pain catastrophizing influences pain processing is not well understood. In experimental settings, pain catastrophizing has been associated with amplified pain processing. This study sought to clarify pain processing mechanisms via experimental induction of pain catastrophizing. Forty women with chronic low back pain were assigned in blocks to an experimental condition, either a psychologist-led 10-minute pain catastrophizing induction or a control (10-minute rest period). All participants underwent a baseline round of several quantitative sensory testing (QST) tasks, followed by the pain catastrophizing induction or the rest period, and then a second round of the same QST tasks. The catastrophizing induction appeared to increase state pain catastrophizing levels. Changes in QST pain were detected for two of the QST tasks administered, weighted pin pain and mechanical allodynia. Although there is a need to replicate our preliminary results with a larger sample, study findings suggest a potential relationship between induced pain catastrophizing and central sensitization of pain. Clarification of the mechanisms through which catastrophizing affects pain modulatory systems may yield useful clinical insights into the treatment of chronic pain. PMID:28348505

  3. Periodontal CGRP contributes to orofacial pain following experimental tooth movement in rats.

    PubMed

    Long, Hu; Liao, Lina; Gao, Meiya; Ma, Wenqiang; Zhou, Yang; Jian, Fan; Wang, Yan; Lai, Wenli

    2015-08-01

    Calcitonin-related gene peptide (CGRP) plays an important role in orofacial inflammatory pain. The aim of this study was to determine whether periodontal CGRP contributes to orofacial pain induced by experimental tooth movement in rats. Male Sprague-Dawley rats were used in this study. Closed coil springs were used to deliver forces. Rats were euthanized on 0d, 1d, 3d, 5d, 7d, and 14d following experimental tooth movement. Then, alveolar bones were obtained for immunostaining of periodontal tissues against CGRP. Two hours prior to euthanasia on each day, orofacial pain levels were assessed through rat grimace scale. CGRP and olcegepant (CGRP receptor antagonist) were injected into periodontal tissues to verify the roles of periodontal CGRP in orofacial pain induced by experimental tooth movement. Periodontal CGRP expression levels and orofacial pain levels were elevated on 1d, 3d, 5d, and 7d following experimental tooth movement. The two indices were significantly correlated with each other and fitted into a dose-response model. Periodontal administration of CGRP could elevate periodontal CGRP expressions and exacerbate orofacial pain. Moreover, olcegepant administration could decrease periodontal CGRP expressions and alleviate orofacial pain. Therefore, periodontal CGRP plays an important role in pain transmission and modulation following experimental tooth movement. We suggest that it may participate in a positive feedback aiming to amplify orofacial pain signals.

  4. An experimental investigation of the effects of preferred and relaxing music listening on pain perception.

    PubMed

    Mitchell, Laura A; MacDonald, Raymond A R

    2006-01-01

    This study investigates the effects of music listening on perception and tolerance of experimentally induced cold pressor pain. Fifty-four participants (34 females, 20 males) each underwent 3 cold pressor trials while listening to (a) white noise, (b) specially designed relaxation music, and (c) their own chosen music. Tolerance time, pain intensity on visual analog scale, and the pain rating index of the McGill Pain Questionnaire and perceived control over the pain were measured in each condition. While listening to their own preferred music, male and female participants tolerated the painful stimulus significantly longer than during both the relaxation music and control conditions. However, only female participants rated the intensity of the pain as significantly lower in the preferred music condition. Both male and female participants reported feeling significantly more control when listening to their preferred music. It is suggested that personal preference is an influential factor when considering the efficacy of music listening for pain relief.

  5. A novel modelling and experimental technique to predict and measure tissue temperature during CO2 laser stimuli for human pain studies.

    PubMed

    Al-Saadi, Mohammed Hamed; Nadeau, V; Dickinson, M R

    2006-07-01

    Laser nerve stimulation is now accepted as one of the preferred methods for applying painful stimuli to human skin during pain studies. One of the main concerns, however, is thermal damage to the skin. We present recent work based on using a CO2 laser with a remote infrared (IR) temperature sensor as a feedback system. A model for predicting the subcutaneous skin temperature derived from the signal from the IR detector allows us to accurately predict the laser parameters, thus maintaining an optimum pain stimulus whilst avoiding dangerous temperature levels, which could result in thermal damage. Another aim is to relate the modelling of the CO2 fibre laser interaction to the pain response and compare these results with practical measurements of the pain threshold for various stimulus parameters. The system will also allow us to maintain a constant skin temperature during the stimulus. Another aim of the experiments underway is to review the psychophysics for pain in human subjects, permitting an investigation of the relationship between temperature and perceived pain.

  6. Effect of experimental chewing on masticatory muscle pain onset

    PubMed Central

    CONTI, Paulo César Rodrigues; SILVA, Rafael dos Santos; de ARAUJO, Carlos dos Reis Pereira; ROSSETI, Leylha Maria N.; YASSUDA, Shigueharu; da SILVA, Renato Oliveira Ferreira; PEGORARO, Luiz Fernando

    2011-01-01

    Objectives To evaluate the effect of a chewing exercise on pain intensity and pressurepain threshold in patients with myofascial pain. Methods Twenty-nine consecutive women diagnosed with myofascial pain (MFP) according to the Research Diagnostic Criteria comprised the experimental group and 15 healthy age-matched female were used as controls. Subjects were asked to chew a gum stick for 9 min and to stay at rest for another 9 min afterwards. Pain intensity was rated on a visual analog scale (VAS) every 3 min. At 0, 9 and 18 min, the pressure-pain threshold (PPT) was measured bilaterally on the masseter and the anterior, medium, and posterior temporalis muscles. Results Patients with myofascial pain reported increase (76%) and no change (24%) on the pain intensity measured with the VAS. A reduction of the PPT at all muscular sites after the exercise and a non-significant recovery after rest were also observed. Conclusion The following conclusions can be drawn: 1. there are at least two subtypes of patients with myofascial pain that respond differently to experimental chewing; 2. the chewing protocol had an adequate discriminative ability in distinguishing patients with myofascial pain from healthy controls. PMID:21437467

  7. Sex, Gender, and Pain: A Review of Recent Clinical and Experimental Findings

    PubMed Central

    Fillingim, Roger B.; King, Christopher D.; Ribeiro-Dasilva, Margarete C.; Rahim-Williams, Bridgett; Riley, Joseph L.

    2009-01-01

    Sex-related influences on pain and analgesia have become a topic of tremendous scientific and clinical interest, especially in the last 10 to 15 years. Members of our research group published reviews of this literature more than a decade ago, and the intervening time period has witnessed robust growth in research regarding sex, gender, and pain. Therefore, it seems timely to revisit this literature. Abundant evidence from recent epidemiologic studies clearly demonstrates that women are at substantially greater risk for many clinical pain conditions, and there is some suggestion that postoperative and procedural pain may be more severe among women than men. Consistent with our previous reviews, current human findings regarding sex differences in experimental pain indicate greater pain sensitivity among females compared with males for most pain modalities, including more recently implemented clinically relevant pain models such as temporal summation of pain and intramuscular injection of algesic substances. The evidence regarding sex differences in laboratory measures of endogenous pain modulation is mixed, as are findings from studies using functional brain imaging to ascertain sex differences in pain-related cerebral activation. Also inconsistent are findings regarding sex differences in responses to pharmacologic and non-pharmacologic pain treatments. The article concludes with a discussion of potential biopsychosocial mechanisms that may underlie sex differences in pain, and considerations for future research are discussed. Perspective This article reviews the recent literature regarding sex, gender, and pain. The growing body of evidence that has accumulated in the past 10 to 15 years continues to indicate substantial sex differences in clinical and experimental pain responses, and some evidence suggests that pain treatment responses may differ for women versus men. PMID:19411059

  8. Intra-articular anaesthesia mitigates established pain in experimental osteoarthritis: a preliminary study of gait impulse redistribution as a biomarker of analgesia pharmacodynamics.

    PubMed

    Matyas, J R; Gutmann, A; Randev, J; Hurtig, M; Bertram, J E A

    2013-09-01

    Develop a sensitive, functional biomarker of persistent joint pain in a large animal model of experimental osteoarthritis. Evaluate Impulse Ratio as a measure of weight distribution among supporting limbs throughout the early natural history of osteoarthritis and with local anaesthesia and analgesia. The distribution of weight bearing in the trot of 11 skeletally-mature dogs was analyzed before and after unilateral surgical intervention (cranial cruciate transection or distal femoral focal impact). The short-term effects of two analgesic treatments (intra-articular lidocaine and intra-dermal meloxicam) were then evaluated as an index of pain relief based on the redistribution of weight-bearing impulse between normal and injured limbs. Impulse Ratio was able to resolve weight redistribution between limbs in both long-term (weekly for over 400 days) and short-term (15 min intervals) joint evaluations. Joint pain relief from lidocaine administration could be reliably tracked over its brief acting time course. Meloxicam administration resulted in ambiguous results, where average weight bearing in the injured limb did not increase, but the variability of limb use changed transiently and reversibly. Joint function and the role of persistent joint pain in the development of osteoarthritis can be investigated effectively and efficiently in a large animal model through the use of Impulse Ratio. Impulse Ratio can be a functionally relevant and sensitive biomarker of locomotion-related joint pain. Copyright © 2013 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

  9. Role of gender norms and group identification on hypothetical and experimental pain tolerance.

    PubMed

    Pool, Gregory J; Schwegler, Andria F; Theodore, Brian R; Fuchs, Perry N

    2007-05-01

    Previous research indicates that men typically tolerate more pain in experimental settings than women. One likely explanation for these group differences in pain tolerance is conformity to traditional, gender group social norms (i.e., the ideal man is masculine and tolerates more pain; the ideal woman is feminine and tolerates less pain). According to self-categorization theory, norms guide behavior to the degree that group members adopt the group identity. Therefore, high-identifying men are expected to conform to gender norms and tolerate more pain than high-identifying women who conform to different gender norms as a guide for their behavior. We conducted two studies to investigate whether gender group identification moderates individuals' conformity to pain tolerance and reporting norms. In the first study, participants indicated their gender identification and expected tolerance of a hypothetical painful stimulus. As anticipated, high-identifying men reported significantly greater pain tolerance than high-identifying women. No differences existed between low-identifying men and women. To determine if self-reported pain tolerance in a role-playing scenario corresponds to actual pain tolerance in an experimental setting, the second study examined pain tolerance to a noxious stimulus induced by electrical stimulation of the index finger. The experimental outcome revealed that high-identifying men tolerated more painful stimulation than high-identifying women. Further, high-identifying men tolerated more pain than low-identifying men. These results highlight the influence of social norms on behavior and suggest the need to further explore the role of norms in pain reporting behaviors.

  10. Sex differences in parent and child pain ratings during an experimental child pain task.

    PubMed

    Moon, E C; Chambers, C T; Larochette, Anne-Claire; Hayton, K; Craig, K D; McGrath, P J

    2008-01-01

    Research in the field of pediatric pain has largely ignored the role of fathers in their children's pain experiences. The first objective of the present study was to examine the effect of the presence of mothers versus fathers on children's subjective ratings, facial expressions and physiological responses to acute pain. The second objective was to examine whether child and parent sex influence parents' proxy ratings of their children's pain. The final objective was to compare levels of agreement between mothers' and fathers' assessments of their children's pain. Participants included 73 children (37 boys, 36 girls), four to 12 years of age, along with 32 fathers and 41 mothers. Children undertook the cold pressor pain task while observed by one of their parents. During the task, the children's heart rates and facial expressions were recorded. Children provided self-reports and parents provided proxy reports of child pain intensity using the seven-point Faces Pain Scale. Neither child nor parent sex had a significant impact on children's subjective reports, facial expressions or heart rates in response to acute pain. Fathers gave their sons higher pain ratings than their daughters, whereas mothers' ratings of their sons' and daughters' pain did not differ. Kappa statistics and t tests revealed that fathers tended to be more accurate judges of their children's pain than mothers. Overall, this research highlights the importance of examining both parent and child sex differences in pediatric pain research.

  11. Experimental human pain models in gastro-esophageal reflux disease and unexplained chest pain

    PubMed Central

    Drewes, Asbjørn Mohr; Arendt-Nielsen, Lars; Funch-Jensen, Peter; Gregersen, Hans

    2006-01-01

    Methods related to experimental human pain research aim at activating different nociceptors, evoke pain from different organs and activate specific pathways and mechanisms. The different possibilities for using mechanical, electrical, thermal and chemical methods in visceral pain research are discussed with emphasis of combinations (e.g., the multimodal approach). The methods have been used widely in assessment of pain mechanisms in the esophagus and have contributed to our understanding of the symptoms reported in these patients. Hence abnormal activation and plastic changes of central pain pathways seem to play a major role in the symptoms in some patients with gastro-esophageal reflux disease and in patients with functional chest pain of esophageal origin. These findings may lead to an alternative approach for treatment in patients that does not respond to conventional medical or surgical therapy. PMID:16718803

  12. A quantitative review of ethnic group differences in experimental pain response: do biology, psychology, and culture matter?

    PubMed

    Rahim-Williams, Bridgett; Riley, Joseph L; Williams, Ameenah K K; Fillingim, Roger B

    2012-04-01

    Pain is a subjectively complex and universal experience. We examine research investigating ethnic group differences in experimental pain response and factors contributing to group differences. We conducted a systematic literature review and analysis of studies using experimental pain stimuli to assess pain sensitivity across multiple ethnic groups. Our search covered the period from 1944 to 2011, and used the PubMed bibliographic database; a reference source containing over 17 million citations. We calculated effect sizes; identified ethnic/racial group categories, pain stimuli, and measures; and examined findings regarding biopsychosociocultural factors contributing to ethnic/racial group differences. We found 472 studies investigating ethnic group differences and pain. Twenty-six of these met our review inclusion criteria of investigating ethnic group differences in experimental pain. The majority of studies included comparisons between African Americans (AA) and non-Hispanic Whites (NHW). There were consistently moderate to large effect sizes for pain tolerance across multiple stimulus modalities; AA demonstrated lower pain tolerance. For pain threshold, findings were generally in the same direction, but effect sizes were small to moderate across ethnic groups. Limited data were available for suprathreshold pain ratings. A subset of studies comparing NHW and other ethnic groups showed a variable range of effect sizes for pain threshold and tolerance. There are potentially important ethnic/racial group differences in experimental pain perception. Elucidating ethnic group differences has translational merit for culturally competent clinical care and for addressing and reducing pain treatment disparities among ethnically/racially diverse groups. Wiley Periodicals, Inc.

  13. The relationship of the audible pop to hypoalgesia associated with high velocity, low amplitude thrust manipulation: A secondary analysis of an experimental study in pain free participants

    PubMed Central

    Bishop, Mark D; Robinson, Michael E; George, Steven Z

    2010-01-01

    Objective High velocity, low amplitude (HVLA) manipulation is an effective treatment for low back pain (LBP); however, the corresponding mechanisms are undetermined. Hypoalgesia is associated with HVLA manipulation and suggests specific mechanisms of action. An audible pop (AP) is also associated with HVLA manipulation; however, the influence of the AP on the hypoalgesia associated with HVLA manipulation is not established. The purpose of the current study was to observe the influence of the AP on hypoalgesia associated with HVLA manipulation. Methods The current study represents a secondary analysis of 40 participants. All participants underwent thermal pain sensitivity testing to their leg and low back using protocols specific to Aδ fiber mediated pain and temporal summation. Next, participants received HVLA manipulation to their low back and the examiner recorded whether or not an AP was perceived. Finally, participants underwent immediate follow up thermal pain sensitivity testing using the same protocols. Separate repeated measure ANOVAs were used to observe changes in pain sensitivity prior to and immediately following HVLA manipulation. Results Hypoalgesia of Aδ fiber mediated pain was observed in the low back following HVLA (p< 0.05) and this was independent of whether an AP was perceived (p> 0.05). Hypoalgesia of temporal summation was observed in the lower extremity following HVLA (p< 0.05) and this was independent of whether an AP was perceived (p= 0.08). However, a moderate effect size for temporal summation was observed favoring participants in whom an AP was perceived. Conclusion The current study suggests hypoalgesia is associated with HVLA manipulation and occurs independently of a perceived AP. Inhibition of lower extremity temporal summation may be larger in individuals in whom an AP is perceived, but further study is necessary to confirm this finding. PMID:20170777

  14. Asians differ from non-Hispanic Whites in experimental pain sensitivity.

    PubMed

    Rowell, Lauren N; Mechlin, Beth; Ji, Ellen; Addamo, Michael; Girdler, Susan S

    2011-08-01

    This study examined differences between Asians and non-Hispanic Whites (Whites) in pain sensitivity, and its relationship to mean arterial pressure (MAP) and heart rate (HR). In 30 Whites (50% female) and 30 Asians (50% female), experimental pain sensitivity was assessed with a hand cold pressor task, yielding measures of pain threshold, tolerance, intensity, and unpleasantness. Mean arterial pressure and HR measurements taken at rest and in response to speech stress were assessed. Perceived stress, anxiety, perfectionism, parental criticism, parental expectations and depressive symptoms were also measured. The results indicated that for the cold pain test, Asians demonstrated significantly lower pain threshold and tolerance levels than Whites. Although no ethnic differences were seen for MAP or HR responses to stress, for Whites higher stress MAP levels were correlated with reduced pain sensitivity, while for Asians higher baseline and stress HR levels were correlated with reduced pain sensitivity. Asians reported higher parental expectations and greater parental criticism than Whites. For Asians only, higher levels of perfectionism were related to more depressive symptoms, anxiety and perceived stress. These results indicate that Asian Americans are more sensitive to experimental pain than Whites and suggest ethnic differences in endogenous pain regulatory mechanisms (e.g. MAP and HR). The results may also have implications for understanding ethnic differences in clinical pain.

  15. Effects of coping statements on experimental pain in chronic pain patients.

    PubMed

    Roditi, Daniela; Robinson, Michael E; Litwins, Nola

    2009-08-19

    The present study measured the effects of catastrophizing self-statements and positive coping self-statements on cold pressor-induced pain. Participants were 58 adult chronic pain patients with current facial pain. It was hypothesized that catastrophizing would lead to a decrease in pain endurance whereas positive coping would lead to an increase in pain endurance. It was also hypothesized that catastrophizing would lead to an increase in peak pain intensity whereas positive coping would lead to a decrease in peak pain intensity. At pretest, participants submerged their nondominant hand in the cold pressor. Pain sensitivity ranges (PSR) were subsequently determined by calculating the difference between tolerance and threshold times. Ratings of peak pain intensity were measured using a pressure sensitive bladder/transducer. Participants underwent random assignment to either a catastrophizing group or a positive coping self-statement group. ANCOVA results revealed that on average, participants employing catastrophizing statements as a coping strategy experienced significantly lower PSR (M = 35.53, SD = 39.71) compared to participants employing positive coping self-statements (M = 73.70, SD = 86.14) when controlling for pretest PSR. Group assignment had no significant influence on peak pain intensity ratings. Thus, our results reveal that manipulation of coping causes changes in pain endurance.

  16. The effects of experimental pain and induced optimism on working memory task performance.

    PubMed

    Boselie, Jantine J L M; Vancleef, Linda M G; Peters, Madelon L

    2016-07-01

    Pain can interrupt and deteriorate executive task performance. We have previously shown that experimentally induced optimism can diminish the deteriorating effect of cold pressor pain on a subsequent working memory task (i.e., operation span task). In two successive experiments we sought further evidence for the protective role of optimism on pain-induced working memory impairments. We used another working memory task (i.e., 2-back task) that was performed either after or during pain induction. Study 1 employed a 2 (optimism vs. no-optimism)×2 (pain vs. no-pain)×2 (pre-score vs. post-score) mixed factorial design. In half of the participants optimism was induced by the Best Possible Self (BPS) manipulation, which required them to write and visualize about a life in the future where everything turned out for the best. In the control condition, participants wrote and visualized a typical day in their life (TD). Next, participants completed either the cold pressor task (CPT) or a warm water control task (WWCT). Before (baseline) and after the CPT or WWCT participants working memory performance was measured with the 2-back task. The 2-back task measures the ability to monitor and update working memory representation by asking participants to indicate whether the current stimulus corresponds to the stimulus that was presented 2 stimuli ago. Study 2 had a 2 (optimism vs. no-optimism)×2 (pain vs. no-pain) mixed factorial design. After receiving the BPS or control manipulation, participants completed the 2-back task twice: once with painful heat stimulation, and once without any stimulation (counter-balanced order). Continuous heat stimulation was used with temperatures oscillating around 1°C above and 1°C below the individual pain threshold. In study 1, the results did not show an effect of cold pressor pain on subsequent 2-back task performance. Results of study 2 indicated that heat pain impaired concurrent 2-back task performance. However, no evidence was found

  17. Is experimentally induced pain associated with socioeconomic status? Do poor people hurt more?

    PubMed Central

    Miljković, Ana; Stipčić, Ana; Braš, Marijana; Đorđević, Veljko; Brajković, Lovorka; Hayward, Caroline; Pavić, Arsen; Kolčić, Ivana; Polašek, Ozren

    2014-01-01

    Background The association of pain and socioeconomic status is widely reported, yet much less clearly understood. The aim of this study was to investigate the association of experimentally induced pain threshold and tolerance with socioeconomic status. Material/Methods The study sample consisted of 319 adult subjects from the population of the island of Vis, Croatia, which was previously shown to have a high level of social homogeneity. A manual dolorimeter was used to measure mechanical pressure pain threshold (least stimulus intensity) and pain tolerance (maximum tolerance stimulus intensity) on both hands. Pain tolerance interval was defined as the difference between pain tolerance and threshold. Years of schooling and material status were used as socioeconomic estimates. Results Both of the socioeconomic estimates were significantly correlated with pain threshold, tolerance, and tolerance interval (P<0.001). The mixed modeling analysis, controlled for the effects of age, gender, and 4 psychological variables, indicated that education was not a significant predictor in any of the 3 models. However, lower material status was significantly associated with lower pain tolerance (P=0.038) and narrower pain tolerance interval (P=0.032), but not with pain threshold (P=0.506). The overall percentages of explained variance were lower in the tolerance interval model (20.2%) than in pain tolerance (23.1%) and threshold (33.1%), suggesting the increasing share of other confounding variables in pain tolerance and even more so in tolerance interval model. Conclusions These results suggest a significant association between experimentally induced pain tolerance and tolerance interval with material status, suggesting that poor people indeed do hurt more. PMID:25029965

  18. Is distraction less effective when pain is threatening? An experimental investigation with the cold pressor task.

    PubMed

    Van Damme, Stefaan; Crombez, Geert; Van Nieuwenborgh-De Wever, Kathleen; Goubert, Liesbet

    2008-01-01

    Distraction is a commonly used strategy to control pain. However there is doubt about its effectiveness as a clinical tool, and results from both experimental and clinical studies remain inconclusive. Recent theoretical advancements suggest that distraction of attention may be less effective when pain is threatening. The aim of the present study was to experimentally investigate this hypothesis. Pain-free volunteers (N=101) participated in a cold pressor test. Half of the participants simultaneously performed a cognitive distraction task, the other half did not. The threat value of the pain was manipulated by means of verbal information. The results showed that distraction resulted in less attention to the pain and lower pain ratings once the cold pressor procedure was halted. The hypothesis that the effectiveness of distraction is modulated by the threat value of pain could not be confirmed. However, threatening information increased catastrophic thoughts and anxiety, and interfered with performance on the distraction task. These findings suggest that caution is required in using distraction as a pain control strategy when the threat value is high, because fearful appraisal of pain is associated with less engagement in distraction tasks.

  19. Experimental tonic hand pain modulates the corticospinal plasticity induced by a subsequent hand deafferentation.

    PubMed

    Mavromatis, N; Gagné, M; Voisin, J I A V; Reilly, K T; Mercier, C

    2016-08-25

    Sensorimotor reorganization is believed to play an important role in the development and maintenance of phantom limb pain, but pain itself might modulate sensorimotor plasticity induced by deafferentation. Clinical and basic research support this idea, as pain prior to amputation increases the risk of developing post-amputation pain. The aim of this study was to examine the influence of experimental tonic cutaneous hand pain on the plasticity induced by temporary ischemic hand deafferentation. Sixteen healthy subjects participated in two experimental sessions (Pain, No Pain) in which transcranial magnetic stimulation was used to assess corticospinal excitability in two forearm muscles (flexor carpi radialis and flexor digitorum superficialis) before (T0, T10, T20, and T40) and after (T60 and T75) inflation of a cuff around the wrist. The cuff was inflated at T45 in both sessions and in the Pain session capsaicin cream was applied on the dorsum of the hand at T5. Corticospinal excitability was significantly greater during the Post-inflation phase (p=0.002) and increased similarly in both muscles (p=0.861). Importantly, the excitability increase in the Post-inflation phase was greater for the Pain than the No-Pain condition (p=0.006). Post-hoc analyses revealed a significant difference between the two conditions during the Post-inflation phase (p=0.030) but no difference during the Pre-inflation phase (p=0.601). In other words, the corticospinal facilitation was greater when pain was present prior to cuff inflation. These results indicate that pain can modulate the plasticity induced by another event, and could partially explain the sensorimotor reorganization often reported in chronic pain populations. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  20. Central Pain Processing in Early-Stage Parkinson's Disease: A Laser Pain fMRI Study

    PubMed Central

    Petschow, Christine; Scheef, Lukas; Paus, Sebastian; Zimmermann, Nadine; Schild, Hans H.; Klockgether, Thomas; Boecker, Henning

    2016-01-01

    Background & Objective Pain is a common non-motor symptom in Parkinson’s disease. As dopaminergic dysfunction is suggested to affect intrinsic nociceptive processing, this study was designed to characterize laser-induced pain processing in early-stage Parkinson’s disease patients in the dopaminergic OFF state, using a multimodal experimental approach at behavioral, autonomic, imaging levels. Methods 13 right-handed early-stage Parkinson’s disease patients without cognitive or sensory impairment were investigated OFF medication, along with 13 age-matched healthy control subjects. Measurements included warmth perception thresholds, heat pain thresholds, and central pain processing with event-related functional magnetic resonance imaging (erfMRI) during laser-induced pain stimulation at lower (E = 440 mJ) and higher (E = 640 mJ) target energies. Additionally, electrodermal activity was characterized during delivery of 60 randomized pain stimuli ranging from 440 mJ to 640 mJ, along with evaluation of subjective pain ratings on a visual analogue scale. Results No significant differences in warmth perception thresholds, heat pain thresholds, electrodermal activity and subjective pain ratings were found between Parkinson’s disease patients and controls, and erfMRI revealed a generally comparable activation pattern induced by laser-pain stimuli in brain areas belonging to the central pain matrix. However, relatively reduced deactivation was found in Parkinson’s disease patients in posterior regions of the default mode network, notably the precuneus and the posterior cingulate cortex. Conclusion Our data during pain processing extend previous findings suggesting default mode network dysfunction in Parkinson’s disease. On the other hand, they argue against a genuine pain-specific processing abnormality in early-stage Parkinson’s disease. Future studies are now required using similar multimodal experimental designs to examine pain processing in more advanced

  1. Central Pain Processing in Early-Stage Parkinson's Disease: A Laser Pain fMRI Study.

    PubMed

    Petschow, Christine; Scheef, Lukas; Paus, Sebastian; Zimmermann, Nadine; Schild, Hans H; Klockgether, Thomas; Boecker, Henning

    2016-01-01

    Pain is a common non-motor symptom in Parkinson's disease. As dopaminergic dysfunction is suggested to affect intrinsic nociceptive processing, this study was designed to characterize laser-induced pain processing in early-stage Parkinson's disease patients in the dopaminergic OFF state, using a multimodal experimental approach at behavioral, autonomic, imaging levels. 13 right-handed early-stage Parkinson's disease patients without cognitive or sensory impairment were investigated OFF medication, along with 13 age-matched healthy control subjects. Measurements included warmth perception thresholds, heat pain thresholds, and central pain processing with event-related functional magnetic resonance imaging (erfMRI) during laser-induced pain stimulation at lower (E = 440 mJ) and higher (E = 640 mJ) target energies. Additionally, electrodermal activity was characterized during delivery of 60 randomized pain stimuli ranging from 440 mJ to 640 mJ, along with evaluation of subjective pain ratings on a visual analogue scale. No significant differences in warmth perception thresholds, heat pain thresholds, electrodermal activity and subjective pain ratings were found between Parkinson's disease patients and controls, and erfMRI revealed a generally comparable activation pattern induced by laser-pain stimuli in brain areas belonging to the central pain matrix. However, relatively reduced deactivation was found in Parkinson's disease patients in posterior regions of the default mode network, notably the precuneus and the posterior cingulate cortex. Our data during pain processing extend previous findings suggesting default mode network dysfunction in Parkinson's disease. On the other hand, they argue against a genuine pain-specific processing abnormality in early-stage Parkinson's disease. Future studies are now required using similar multimodal experimental designs to examine pain processing in more advanced stages of Parkinson's disease.

  2. IL17 Mediates Pelvic Pain in Experimental Autoimmune Prostatitis (EAP)

    PubMed Central

    Murphy, Stephen F.; Schaeffer, Anthony J.; Done, Joseph; Wong, Larry; Bell-Cohn, Ashlee; Roman, Kenny; Cashy, John; Ohlhausen, Michelle; Thumbikat, Praveen

    2015-01-01

    Chronic pelvic pain syndrome (CPPS) is the most common form of prostatitis, accounting for 90–95% of all diagnoses. It is a complex multi-symptom syndrome with unknown etiology and limited effective treatments. Previous investigations highlight roles for inflammatory mediators in disease progression by correlating levels of cytokines and chemokines with patient reported symptom scores. It is hypothesized that alteration of adaptive immune mechanisms results in autoimmunity and subsequent development of pain. Mouse models of CPPS have been developed to delineate these immune mechanisms driving pain in humans. Using the experimental autoimmune prostatitis (EAP) in C57BL/6 mice model of CPPS we examined the role of CD4+T-cell subsets in the development and maintenance of prostate pain, by tactile allodynia behavioral testing and flow cytometry. In tandem with increased CD4+IL17A+ T-cells upon EAP induction, prophylactic treatment with an anti-IL17 antibody one-day prior to EAP induction prevented the onset of pelvic pain. Therapeutic blockade of IL17 did not reverse pain symptoms indicating that IL17 is essential for development but not maintenance of chronic pain in EAP. Furthermore we identified a cytokine, IL7, to be associated with increased symptom severity in CPPS patients and is increased in patient prostatic secretions and the prostates of EAP mice. IL7 is fundamental to development of IL17 producing cells and plays a role in maturation of auto-reactive T-cells, it is also associated with autoimmune disorders including multiple sclerosis and type-1 diabetes. More recently a growing body of research has pointed to IL17’s role in development of neuropathic and chronic pain. This report presents novel data on the role of CD4+IL17+ T-cells in development and maintenance of pain in EAP and CPPS. PMID:25933188

  3. Experimenter Effects on Pain Reporting in Women Vary across the Menstrual Cycle

    PubMed Central

    Vigil, Jacob M.; DiDomenico, Jared; Strenth, Chance; Coulombe, Patrick; Kruger, Eric; Mueller, Andrea A.; Guevara Beltran, Diego; Adams, Ian

    2015-01-01

    Background. Separate lines of research have shown that menstrual cycling and contextual factors such as the gender of research personnel influence experimental pain reporting. Objectives. This study examines how brief, procedural interactions with female and male experimenters can affect experimentally reported pain (cold pressor task, CPT) across the menstrual cycle. Methods. Based on the menstrual calendars 94 naturally cycling women and 38 women using hormonal contraceptives (Mage = 19.83,  SD = 3.09) were assigned to low and high fertility groups. This assignment was based on estimates of their probability of conception given their current cycle day. Experimenters (12 males, 7 females) engaged in minimal procedural interactions with participants before the CPT was performed in solitude. Results. Naturally cycling women in the high fertility group showed significantly higher pain tolerance (81 sec, d = .79) following interactions with a male but not a female experimenter. Differences were not found for women in the low fertility or contraceptive groups. Discussion. The findings illustrate that menstrual functioning moderates the effect that experimenter gender has on pain reporting in women. Conclusion. These findings have implications for standardizing pain measurement protocols and understanding how basic biopsychosocial mechanisms (e.g., person-perception systems) can modulate pain experiences. PMID:25892990

  4. Virtual reality immersion method of distraction to control experimental ischemic pain.

    PubMed

    Magora, Florella; Cohen, Sarale; Shochina, Mara; Dayan, Ehud

    2006-04-01

    Virtual reality immersion has been advocated as a new effective adjunct to drugs for pain control. The attenuation of pain perception and unpleasantness has been attributed to the patient's attention being diverted from the real, external environment through immersion in a virtual environment transmitted by an interactive 3-D software computer program via a VR helmet. To investigate whether VR immersion can extend the amount of time subjects can tolerate ischemic tourniquet pain. The study group comprised 20 healthy adult volunteers. The pain was induced by an inflated blood pressure cuff during two separate, counterbalanced, randomized experimental conditions for each subject: one with VR and the control without VR exposure. The VR equipment consisted of a standard computer, a lightweight helmet and an interactive software game. Tolerance time to ischemia was significantly longer for VR conditions than for those without (P < 0.001). Visual Analogue Scale (0-10) ratings were recorded for pain intensity, pain unpleasantness, and the time spent thinking about pain. Affective distress ratings of unpleasantness and of time spent thinking about pain were significantly lower during VR as compared with the control condition (P< 0.003 and 0.001 respectively). The VR method in pain control was shown to be beneficial. The relatively inexpensive equipment will facilitate the use of VR immersion in clinical situations. Future research is necessary to establish the optimal selection of clinical patients appropriate for VR pain therapy and the type of software required according to age, gender, personality, and cultural factors.

  5. The role of periodontal ASIC3 in orofacial pain induced by experimental tooth movement in rats.

    PubMed

    Gao, Meiya; Long, Hu; Ma, Wenqiang; Liao, Lina; Yang, Xin; Zhou, Yang; Shan, Di; Huang, Renhuan; Jian, Fan; Wang, Yan; Lai, Wenli

    2016-12-01

    This study aimed to clarify the roles of Acid-sensing ion channel 3 (ASIC3) in orofacial pain following experimental tooth movement. Sixty male Sprague-Dawley rats were divided into the experimental group (40g, n = 30) and the sham group (0g, n = 30). Closed coil springs were ligated between maxillary incisor and molars to achieve experimental tooth movement. Rat grimace scale (RGS) scores were assessed at 0, 1, 3, 5, 7, and 14 days after the placement of the springs. ASIC3 immunostaining was performed and the expression levels of ASIC3 were measured through integrated optical density/area in Image-Pro Plus 6.0. Moreover, 18 rats were divided into APETx2 group (n = 6), amiloride group (n = 6), and vehicle group (n = 6), and RGS scores were obtained compared among them to verify the roles of ASIC3 in orofacial pain following tooth movement. ASIC3 expression levels became significantly higher in the experimental group than in sham group on 1, 3, and 5 days and became similar on 7 and 14 days. Pain levels (RGS scores) increased in both groups and were significantly higher in the experimental group on 1, 3, 5, and 7 days and were similar on 14 days. Periodontal ASIC3 expression levels were correlated with orofacial pain levels following experimental tooth movement. Periodontal administrations of ASIC3 antagonists (APETx2 and amiloride) could alleviate pain. This study needs to be better evidenced by RNA interference of ASIC3 in periodontal tissues in rats following experimental tooth movement. Moreover, we hope further studies would concentrate on the pain perception of ASIC3 knockout (ASIC3(-/-)) mice. Our results suggest that periodontal ASIC3 plays an important role in orofacial pain induced by experimental tooth movement. © The Author 2015. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  6. Placebo effect of an inert gel on experimentally induced leg muscle pain

    PubMed Central

    Hopker, James G; Foad, Abigail J; Beedie, Christopher J; Coleman, Damian A; Leach, Geoffrey

    2010-01-01

    Purpose This study examined the therapeutic effects of an inert placebo gel on experimentally induced muscle pain in a sports therapy setting. It aimed to investigate the degree to which conditioned analgesia, coupled with an expectation of intervention, was a factor in subsequent analgesia. Methods Participants were sixteen male and eight female sports therapy students at a UK University. With institutional ethics board approval and following informed consent procedures, each was exposed to pain stimulus in the lower leg in five conditions, ie, conditioning, prebaseline, experimental (two placebo gel applications), and postbaseline. In conditioning trials, participants identified a level of pain stimulus equivalent to a perceived pain rating of 6/10. An inert placebo gel was then applied to the site with the explicit instruction that it was an analgesic. Participants were re-exposed to the pain stimulus, the level of which, without their knowledge, had been decreased, creating the impression of an analgesic effect resulting from the gel. In experimental conditions, the placebo gel was applied and the level of pain stimulus required to elicit a pain rating of 6/10 recorded. Results Following application of the placebo gel, the level of pain stimulus required to elicit a pain rating of 6/10 increased by 8.2%. Application of the placebo gel significantly decreased participant’s perceptions of muscle pain (P = 0.001). Conclusion Subjects’ experience and expectation of pain reduction may be major factors in the therapeutic process. These factors should be considered in the sports therapeutic environment. PMID:24198560

  7. Changes in pain catastrophizing predict later changes in fibromyalgia clinical and experimental pain report: cross-lagged panel analyses of dispositional and situational catastrophizing

    PubMed Central

    2012-01-01

    Introduction Fibromyalgia (FM), characterized by wide-spread diffuse pain and sensory abnormalities, is associated with elevated indices of distress and pain-related catastrophizing compared to both pain-free samples and those with chronic pain conditions. Catastrophizing is a pervasive negative mental set, and is a strong predictor of negative pain-related outcomes such as clinical pain intensity, and physical disability. Situational catastrophizing, measured in the context of experimentally-induced pain, is strongly related to enhanced pain sensitivity, a core aspect of the pathophysiology of fibromyalgia. However, little is known regarding the temporal course of the association between catastrophizing and pain-related "outcomes". Most studies involve only static assessments of pain and catastrophizing at a single time point, which provides little insight into the direction of the observed associations. We sought to investigate the temporal relationships between catastrophizing and indices of both clinical pain (substudy 1) and experimentally-induced pain (substudy 2) in a larger randomized controlled longitudinal trial. Methods Fifty-seven patients with FM completed catastrophizing, depression, and pain questionnaires as well as laboratory cold pressor pain testing at baseline, post-intervention and three month follow-up during a lifestyle physical activity study. Cross-lagged panel analyses were used to address these temporal relationships. Results In substudy 1, analyses revealed that pre-to-post changes in dispositional catastrophizing ratings prospectively accounted for unique variance in subsequent post-to-follow-up changes in clinical pain ratings (p = 0.005), while pre-to-post changes in pain ratings did not account for unique variance in post-to-follow-up changes in catastrophizing ratings. An identical pattern was observed experimentally in substudy 2, with pre-to-post changes in situational catastrophizing ratings prospectively accounting for unique

  8. Clinical pharmacology of analgesics assessed with human experimental pain models: bridging basic and clinical research

    PubMed Central

    Oertel, Bruno Georg; Lötsch, Jörn

    2013-01-01

    The medical impact of pain is such that much effort is being applied to develop novel analgesic drugs directed towards new targets and to investigate the analgesic efficacy of known drugs. Ongoing research requires cost-saving tools to translate basic science knowledge into clinically effective analgesic compounds. In this review we have re-examined the prediction of clinical analgesia by human experimental pain models as a basis for model selection in phase I studies. The overall prediction of analgesic efficacy or failure of a drug correlated well between experimental and clinical settings. However, correct model selection requires more detailed information about which model predicts a particular clinical pain condition. We hypothesized that if an analgesic drug was effective in an experimental pain model and also a specific clinical pain condition, then that model might be predictive for that particular condition and should be selected for development as an analgesic for that condition. The validity of the prediction increases with an increase in the numbers of analgesic drug classes for which this agreement was shown. From available evidence, only five clinical pain conditions were correctly predicted by seven different pain models for at least three different drugs. Most of these models combine a sensitization method. The analysis also identified several models with low impact with respect to their clinical translation. Thus, the presently identified agreements and non-agreements between analgesic effects on experimental and on clinical pain may serve as a solid basis to identify complex sets of human pain models that bridge basic science with clinical pain research. PMID:23082949

  9. Effects of restricted environmental stimulation: enhancement of hypnotizability for experimental and chronic pain control.

    PubMed

    Barabasz, A F; Barabasz, M

    1989-07-01

    Enhancement of hypnotizability and pain tolerance has been demonstrated using restricted environmental stimulation therapy (REST) with university students as Ss (A. F. Barabasz, 1982). The purpose of the present study was to determine whether or not similar results could be obtained with chronic pain patients. Ss consisted of outpatients in treatment for conditions in which pain is prominent who also demonstrated low hypnotizability after repeated hypnosis plateau sessions. 2 groups of Ss were exposed to REST. Situational demand characteristics (Orne, 1962) favored an increase in hypnotizability for REST Group 1 (high demand). REST Group 2 (low demand) was exposed to situational demand characteristics designed to disguise the experimental hypothesis. 2 groups of control Ss were exposed to the same alternative demand characteristic manipulations as the experimental groups, but environmental stimulation was maintained. The Stanford Hypnotic Susceptibility Scale, Form C (SHSS:C) of Weitzenhoffer and E. R. Hilgard (1962), including a posthypnotic suggestion for an anesthetic reaction, and an ischemic pain test were administered prior to treatment and again immediately following treatment. After 6 hours of REST, significant increases in SHSS:C scores were found for high-demand and low-demand experimental Ss, as well as for high-demand control Ss. No such increase was found for low-demand controls. Significant decreases in pain scores were found for both high- and low-demand experimental groups. No significant pain score decreases were found for either control group, suggesting a relatively weak effect of demand characteristics. An independent postexperimental inquiry suggested all Ss believed they received active treatments. The inquiry, conducted 10-15 days after the experiment, also revealed a majority of experimental Ss were using hypnosis on a daily basis to reduce pain with a substantial decrease in pain medication. Only 2 control Ss (highest in hypnotizability

  10. Modulation of trigeminal laser evoked potentials and laser silent periods by homotopical experimental pain.

    PubMed

    Romaniello, Antonietta; Arendt-Nielsen, Lars; Cruccu, Giorgio; Svensson, Peter

    2002-07-01

    Cutaneous laser stimulation activates predominantly the A-delta and C mechano-heat nociceptors. Applied to the perioral region, low intensity CO(2)-laser pulses evoke reproducible trigeminal cortical evoked potentials (LEPs). High intensity CO(2)-laser stimuli induce a reflex response in the contracted jaw-closing muscle, the so-called laser silent period (LSP). Both LEPs and LSP provide a useful tool to study the physiology of the trigeminal nociceptive system. In ten healthy subjects we recorded the subjective ratings of the perioral laser stimulation and the trigeminal LEPs and LSP before, during and after homotopic experimental tonic muscle (infusion of hypertonic saline into the masseter muscle) and tonic skin pain (topical application of capsaicin to the cheek). LEPs were recorded from the vertex at two stimulus intensities: low (1.1 x pain threshold, PTh) and high (1.5 x PTh). LSP from masseter and temporalis muscles were recorded bilaterally through surface electromyographic (EMG) electrodes. CO(2)-laser pulses were applied to the perioral region (V2/V3) on the painful and non-painful side. The amplitude of LEPs increased with higher stimulus intensities (P<0.0001), but were suppressed by 42.3+/-5.3% during experimental muscle pain (P<0.0001) and by 41.6+/-3.2% during skin pain (P<0.0001). No pain-related effects were observed for the N and P latency of the LEPs (P> 0.20). The LSP in the masseter and temporalis muscles had similar onset-latency (80+/-5 ms), offset-latency (111+/-5 ms) and duration (31+/-4 ms). Experimental pain had no effect on the onset- and offset-latency (P>0.05). Experimental pain, whether from muscle or from skin, reduced the degree of suppression (P<0.01) and the area under the EMG curve (P< 0.005) of the LSP. The LSP was still suppressed during the post-pain recordings when the skin pain had disappeared (P<0.05). In all experiments experimental tonic pain decreased the subjective ratings of the perioral laser stimulation (P< 0

  11. A randomized, double-blind, positive-controlled, 3-way cross-over human experimental pain study of a TRPV1 antagonist (V116517) in healthy volunteers and comparison with preclinical profile.

    PubMed

    Arendt-Nielsen, Lars; Harris, Steve; Whiteside, Garth T; Hummel, Michele; Knappenberger, Terri; OʼKeefe, Sarah; Kapil, Ram; Kyle, Don

    2016-09-01

    This experimental, translational, experimental pain, single-center, randomized, double-blind, single-dose, 3-treatment, 3-period cross-over proof-of-concept volunteer trial studied the efficacy of a novel TRPV1 antagonist (V116517) on capsaicin- and UV-B-induced hyperalgesia. Heat and pressure pain thresholds, von Frey stimulus-response functions, and neurogenic inflammation were assessed together with safety. Each treatment period was 4 days. The 3 single oral treatments were 300 mg V116517, 400 mg celecoxib (a COX-2 inhibitor), and placebo. The heat pain detection and tolerance thresholds were increased significantly (P < 0.0001) by V116517. Heat pain detection and tolerance thresholds showed significantly less capsaicin hyperalgesia after V116517 (P = 0.004 and P < 0.0001, respectively). Celecoxib reduced UV-B-provoked pressure pain sensitization (P = 0.01). Laser Doppler flowmetry and erythema index after UV-B were significantly (P < 0.0001) reduced by celecoxib. Stimulus-response function in capsaicin-treated areas showed significant differences between both celecoxib and placebo and between V116517 and placebo. The body temperature showed no change, and no side effects were reported for any of the treatments. The TRPV1 antagonists and the COX-2 inhibitor showed different antihyperalgesic profiles indicating different clinical targets. In addition, the preclinical profile of V116517 in rat models of UV-B and capsaicin-induced hypersensitivity was compared with the human experimental data and overall demonstrated an alignment between 2 of the 3 end points tested. The TRPV1 antagonist showed a potent antihyperalgesic action without changing the body temperature but heat analgesia may be a potential safety issue.

  12. Sex Differences in How Social Networks and Relationship Quality Influence Experimental Pain Sensitivity

    PubMed Central

    Vigil, Jacob M.; Rowell, Lauren N.; Chouteau, Simone; Chavez, Alexandre; Jaramillo, Elisa; Neal, Michael; Waid, David

    2013-01-01

    This is the first study to examine how both structural and functional components of individuals’ social networks may moderate the association between biological sex and experimental pain sensitivity. One hundred and fifty-two healthy adults (mean age = 22yrs., 53% males) were measured for cold pressor task (CPT) pain sensitivity (i.e., intensity ratings) and core aspects of social networks (e.g., proportion of friends vs. family, affection, affirmation, and aid). Results showed consistent sex differences in how social network structures and intimate relationship functioning modulated pain sensitivity. Females showed higher pain sensitivity when their social networks consisted of a higher proportion of intimate types of relationship partners (e.g., kin vs. non kin), when they had known their network partners for a longer period of time, and when they reported higher levels of logistical support from their significant other (e.g., romantic partner). Conversely, males showed distinct patterns in the opposite direction, including an association between higher levels of logistical support from one’s significant other and lower CPT pain intensity. These findings show for the first time that the direction of sex differences in exogenous pain sensitivity is likely dependent on fundamental components of the individual’s social environment. The utility of a social-signaling perspective of pain behaviors for examining, comparing, and interpreting individual and group differences in experimental and clinical pain reports is discussed. PMID:24223836

  13. Sex differences in how social networks and relationship quality influence experimental pain sensitivity.

    PubMed

    Vigil, Jacob M; Rowell, Lauren N; Chouteau, Simone; Chavez, Alexandre; Jaramillo, Elisa; Neal, Michael; Waid, David

    2013-01-01

    This is the first study to examine how both structural and functional components of individuals' social networks may moderate the association between biological sex and experimental pain sensitivity. One hundred and fifty-two healthy adults (mean age = 22yrs., 53% males) were measured for cold pressor task (CPT) pain sensitivity (i.e., intensity ratings) and core aspects of social networks (e.g., proportion of friends vs. family, affection, affirmation, and aid). Results showed consistent sex differences in how social network structures and intimate relationship functioning modulated pain sensitivity. Females showed higher pain sensitivity when their social networks consisted of a higher proportion of intimate types of relationship partners (e.g., kin vs. non kin), when they had known their network partners for a longer period of time, and when they reported higher levels of logistical support from their significant other (e.g., romantic partner). Conversely, males showed distinct patterns in the opposite direction, including an association between higher levels of logistical support from one's significant other and lower CPT pain intensity. These findings show for the first time that the direction of sex differences in exogenous pain sensitivity is likely dependent on fundamental components of the individual's social environment. The utility of a social-signaling perspective of pain behaviors for examining, comparing, and interpreting individual and group differences in experimental and clinical pain reports is discussed.

  14. Empathy Predicts an Experimental Pain Reduction During Touch.

    PubMed

    Goldstein, Pavel; Shamay-Tsoory, Simone G; Yellinek, Shahar; Weissman-Fogel, Irit

    2016-10-01

    Previous studies have provided evidence for pain-alleviating effects of segmental tactile stimulation, yet the effect of social touch and its underlying mechanism is still unexplored. Considering that the soma affects the way we think, feel, and interact with others, it has been proposed that touch may communicate emotions, including empathy, interacting with the identity of the toucher. Thus, the goal of the current study was to examine the analgesic effects of social touch, and to test the moderating role of the toucher's empathy in analgesia using an ecological paradigm. Tonic heat stimuli were administered to women. Concurrently, their partners either watched or touched their hands, a stranger touched their hands, or no one interacted with them. The results revealed diminished levels of pain during partners' touch compared with all other control conditions. Furthermore, taking into account the dyadic interaction, only during the touch condition we found 1) a significant relationship between the partners' pain ratings, and 2) a significant negative relationship between the male touchers' empathy and the pain experience of their female partners. The findings highlight the powerful analgesic effect of social touch and suggest that empathy between romantic partners may explain the pain-alleviating effects of social touch. Pain research mostly concentrates on different factors around a single pain target, without taking into account various social interactions with the observers. Our findings support the idea that pain perception models should be extended, taking into account some psychological characteristics of observers. Our conclusions are on the basis of advanced statistical methods. Copyright © 2016 American Pain Society. Published by Elsevier Inc. All rights reserved.

  15. Women with dysmenorrhoea are hypersensitive to experimentally induced forearm ischaemia during painful menstruation and during the pain-free follicular phase.

    PubMed

    Iacovides, S; Avidon, I; Baker, F C

    2015-07-01

    Monthly primary dysmenorrhoeic pain is associated with increased sensitivity to painful stimuli, particularly in deep tissue. We investigated whether women with dysmenorrhoea, compared with controls, have increased sensitivity to experimentally induced deep-tissue muscle ischaemia in a body area distant from that of referred menstrual pain. The sub-maximal effort tourniquet test was used to induce forearm ischaemia in 11 women with severe dysmenorrhoea and in nine control women both during menstruation and in the follicular phase of the menstrual cycle. Von Frey hair assessments confirmed the presence of experimental ischaemia. Women rated the intensity of menstrual and ischaemic pain on a 100-mm visual analogue scale. Women with dysmenorrhoea [mean (SD): 68 (20) mm] reported significantly greater menstrual pain compared with controls [mean (SD): 2 (6) mm; p = 0.0001] during the menstruation phase. They also rated their forearm ischaemic pain as significantly greater than the controls during the menstruation [dysmenorrhoeics vs. controls mean (SD): 58 (19) mm vs. 31 (21) mm, p < 0.01] and follicular [dysmenorrhoeics vs. controls mean (SD): 60 (18) mm vs. 40 (14) mm, p < 0.01] phases of the menstrual cycle. These data show that compared with controls, women who experience severe recurrent dysmenorrhoea have deep-tissue hyperalgesia to ischaemic pain in muscles outside of the referred area of menstrual pain both during the painful menstruation phase and pain-free follicular phase. These findings suggest the presence of long-lasting changes in muscle pain sensitivity in women with dysmenorrhoea. Our findings that dysmenorrhoeic women are hyperalgesic to a clinically relevant, deep-muscle ischaemic pain in areas outside of referred menstrual pain confirm other studies showing long-lasting changes in pain sensitivity outside of the painful period during menstruation. © 2014 European Pain Federation - EFIC®

  16. Analgesics as reinforcers with chronic pain: Evidence from operant studies.

    PubMed

    Ewan, Eric E; Martin, Thomas J

    2013-12-17

    Previously preclinical pain research has focused on simple behavioral endpoints to assess the efficacy of analgesics in acute and chronic pain models, primarily reflexive withdrawal from an applied mechanical or thermal stimulus. However recent research has been aimed at investigating other behavioral states in the presence of pain, including spontaneous, non-elicited pain. One approach is to investigate the reinforcing effects of analgesics in animals with experimental pain, which should serve as reinforcers by virtue of their ability to alleviate the relevant subjective states induced by pain. The gold standard for assessing drug reinforcement is generally accepted to be drug self-administration, and this review highlights the ability of drugs to serve as reinforcers in animals with experimental neuropathic pain, and the extent to which this behavior is altered in chronic pain states. Additionally, intracranial self-stimulation is an operant procedure that has been used extensively to study drug reinforcement mechanisms and the manner in which neuropathic pain alters the ability of drugs to serve as reinforcers in this paradigm will also be discussed. Drug self-administration and intracranial self-stimulation have promise as tools to investigate behavioral effects of analgesics in animals with chronic pain, particularly regarding the mechanisms through which these drugs motivate consumption in a chronic pain state.

  17. Analgesics as Reinforcers with Chronic Pain: Evidence from Operant Studies

    PubMed Central

    Ewan, Eric E.; Martin, Thomas J.

    2013-01-01

    Previously preclinical pain research has focused on simple behavioral endpoints to assess the efficacy of analgesics in acute and chronic pain models, primarily reflexive withdrawal from an applied mechanical or thermal stimulus. However recent research has been aimed at investigating other behavioral states in the presence of pain, including spontaneous, non-elicited pain. One approach is to investigate the reinforcing effects of analgesics in animals with experimental pain, which should serve as reinforcers by virtue of their ability to alleviate the relevant subjective states induced by pain. The gold standard for assessing drug reinforcement is generally accepted to be drug self-administration, and this review highlights the ability of drugs to serve as reinforcers in animals with experimental neuropathic pain, and the extent to which this behavior is altered in chronic pain states. Additionally, intracranial self-stimulation is an operant procedure that has been used extensively to study drug reinforcement mechanisms and the manner in which neuropathic pain alters the ability of drugs to serve as reinforcers in this paradigm will also be discussed. Drug self-administration and intracranial self-stimulation have promise as tools to investigate behavioral effects of analgesics in animals with chronic pain, particularly regarding the mechanisms through which these drugs motivate consumption in a chronic pain state. PMID:23973302

  18. Gender role affects experimental pain responses: a systematic review with meta-analysis.

    PubMed

    Alabas, O A; Tashani, O A; Tabasam, G; Johnson, M I

    2012-10-01

    Gender role refers to the culturally and socially constructed meanings that describe how women and men should behave in certain situations according to feminine and masculine roles learned throughout life. The aim of this meta-analysis was to evaluate the relationship between gender role and experimental pain responses in healthy human participants. We searched computerized databases for studies published between January 1950 and May 2011 that had measured gender role in healthy human adults and pain response to noxious stimuli. Studies were entered into a meta-analysis if they calculated a correlation coefficient (r) for gender role and experimental pain. Searches yielded 4465 'hits' and 13 studies were eligible for review. Sample sizes were 67-235 participants and the proportion of female participants was 45-67%. Eight types of gender role instrument were used. Meta-analysis of six studies (406 men and 539 women) found a significant positive correlation between masculine and feminine personality traits and pain threshold and tolerance, with a small effect size (r = 0.17, p = 0.01). Meta-analysis of four studies (263 men and 297 women) found a significant negative correlation between gender stereotypes specific to pain and pain threshold and tolerance, with a moderate effect size (r = -0.41, p < 0.001). In conclusion, individuals who considered themselves more masculine and less sensitive to pain than the typical man showed higher pain thresholds and tolerances. Gender stereotypes specific to pain scales showed stronger associations with sex differences in pain sensitivity response than masculine and feminine personality trait scales.

  19. Sex-independent suppression of experimental inflammatory pain by minocycline in two mouse strains.

    PubMed

    Bastos, Leandro F S; Prazeres, Júlia D M; Godin, Adriana M; Menezes, Raquel R; Soares, Darly G; Ferreira, Wallace C; Dutra, Marcela M G B; Machado, Renes R; Coelho, Márcio M

    2013-10-11

    The research on sex differences in nociception and antinociception as well as sex and gender differences in pain and analgesia is a maturing field. There is a vast literature showing experimental and clinical pain suppressive effects induced by minocycline, especially in inflammatory pain. However, as far as we know, possible qualitative or quantitative sex differences in those effects remained to be examined. By employing the formalin test, which has two phases of experimental pain behavior that models nociceptive pain (i.e., first phase) and inflammatory pain (i.e., second phase), we initially evaluated the effect induced by minocycline in female or male C57BL/6 mice. The treatment reduced the second phase of licking behavior in both females and males, and the effects were quantitatively similar in both sexes. Likewise, the same sex-independent effect was observed in Swiss mice, suggesting a genotype-unspecific sex-independent effect. While minocycline is already being tested in clinical trials, this appears to be the first preclinical investigation of sex differences in the experimental pain suppressive effects induced by this widely studied drug. The independence of sex in the antinociceptive effect induced by minocycline may be hopefully translated to gender-independent analgesic effects, which would be surely promising in a therapeutic paradigm. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  20. Peripheral sensory neuron injury contributes to neuropathic pain in experimental autoimmune encephalomyelitis

    PubMed Central

    Wang, I-Ching; Chung, Chen-Yen; Liao, Fang; Chen, Chih-Cheng; Lee, Cheng-Han

    2017-01-01

    Multiple sclerosis (MS)-induced neuropathic pain deteriorates quality of life in patients but is often refractory to treatment. In experimental autoimmune encephalomyelitis (EAE), a rodent model of MS, animals develop neuropathy and inflammation-induced tissue acidosis, which suggests the involvement of acid-sensing ion channels (ASICs). Also, peripheral neuropathy is reported in MS patients. However, the involvement of the peripheral nervous system (PNS) in MS neuropathic pain remains elusive. This study investigated the contribution of ASICs and peripheral neuropathy in MS-induced neuropathic pain. Elicited pain levels were as high in Asic1a−/−, Asic2−/− and Asic3−/− mice as wild-type mice even though only Asic1a−/− mice showed reduced EAE disease severity, which indicates that pain in EAE was independent of disease severity. We thus adopted an EAE model without pertussis toxin (EAEnp) to restrain activated immunity in the periphery and evaluate the PNS contribution to pain. Both EAE and EAEnp mice showed similar pain behaviors and peripheral neuropathy in nerve fibers and DRG neurons. Moreover, pregabalin significantly reduced neuropathic pain in both EAE and EAEnp mice. Our findings highlight the essential role of the PNS in neuropathic pain in EAE and pave the way for future development of analgesics without side effects in the CNS. PMID:28181561

  1. Social comparison performance standards, threat, and tolerance for experimentally-induced pain.

    PubMed

    Jackson, Todd; Phillips, Heath

    2011-11-01

    Social modelling experiments have illustrated how upward social comparisons (i.e., observing pain tolerant role models) can facilitate tolerance relative to downward social comparison (i.e., observing pain intolerant alternatives). However, because clinical studies suggest that people prefer to make downward social comparisons with less fortunate others when they are threatened or overwhelmed with pain or illness, it seems plausible that upward social comparisons confer fewer benefits when pain is appraised as threatening. To address this issue, we assessed effects of verbally-presented upward and downward social comparison standards on tolerance for cold pressor pain among 124 Australian adults (44 men, 80 women) primed with either more or less threatening orienting information about task-related pain sensations. As predicted, participants exposed to the lower threat orienting prime and upward comparison performance standard were significantly more pain tolerant than peers in all other conditions. Conversely, the average tolerance time for participants presented with the higher threat orienting prime and upward comparison standard did not differ from that of either downward comparison group. The research highlighted powerful situational influences on tolerance for experimental pain and identified conditions under which verbally-presented upward social comparison standards may facilitate and hinder the capacity to bear pain.

  2. Evaluation of ketamine, nimodipine, gabapentin and imipramine in partial sciatic nerve transection model of neuropathic pain in rat: an experimental study.

    PubMed

    Hota, D; Bansal, V; Pattanaik, S

    2007-09-01

    The aim of this research is to study the effects of nimodipine, gabapentin, ketamine and imipramine in the partial sciatic nerve transection (PST) model of neuropathic pain in rats. PST was produced in young Wistar rats of either sex by partial destruction of the sciatic nerve. A decrease in the latency to paw withdrawal reaction on the hot plate was considered as development of neuropathy. The drugs were given daily from the third day of the procedure, and evaluation was done on days 7, 14, 21 and 28. There was a significant decrease (p < 0.05) in the paw withdrawal response in the nimodipine group from day 14 onward when compared with the control group. In the ketamine and imipramine group, this response was seen from day 21 onward. The effect persisted till the end of the study. There was no improvement in the gabapentin group. The results of our study show that nimodipine (dihydropyridine calcium channel blocker), ketamine (NMDA antagonist) and imipramine (tricyclic antidepressant) modulated hyperalgesia and allodynia in the PST model of neuropathy. Gabapentin (an alpha-2 delta calcium subunit blocker) did not show any effect in this model of neuropathy. The widespread use of gabapentin in various types of neuropathic pain thus needs to be reevaluated.

  3. Ethnicity Interacts with the OPRM1 Gene in Experimental Pain Sensitivity

    PubMed Central

    Hastie, Barbara A.; Riley, Joseph L.; Kaplan, Lee; Herrera, Dyanne G.; Campbell, Claudia M.; Virtusio, Kathrina; Mogil, Jeffrey S.; Wallace, Margaret R.; Fillingim, Roger B.

    2013-01-01

    Robust inter-individual variation in pain sensitivity has been observed and recent evidence suggests that some of the variability may be genetically-mediated. Our previous data revealed significantly higher pressure pain thresholds among individuals possessing the minor G allele of the A118G SNP of the mu-opioid receptor gene (OPRM1) compared to those with two consensus alleles. Moreover, ethnic differences in pain sensitivity have been widely reported. Yet, little is known about the potential interactive associations of ethnicity and genotype with pain perception. This study aimed to identify ethnic differences in OPRM1 allelic associations with experimental pain responses. Two-hundred and forty-seven healthy young adults from three ethnic groups (81 African Americans; 79 non-white Hispanics; and 87 non-Hispanic whites) underwent multiple experimental pain modalities (thermal, pressure, ischemic, cold pressor). Few African Americans (7.4%) expressed the rare allele of OPRM1 compared to non-Hispanic-whites and Hispanics (28.7% vs. 27.8%, respectively). Across the entire sample, OPRM1 genotype did not significantly affect pain sensitivity. However, analysis in each ethnic group separately revealed significant genotype effects for most pain modalities among non-Hispanic-whites (ps<0.05) but not Hispanics or African Americans. The G allele was associated with decreased pain sensitivity among whites only; a trend in the opposite direction emerged in Hispanics. The reasons for this dichotomy are unclear but may involve ethnic differences in haplotypic structure or A118G may be a tag-SNP linked to other functional polymorphisms. These findings demonstrate an ethnic-dependent association of OPRM1 genotype with pain sensitivity. Additional research is warranted to uncover the mechanisms influencing these relationships. PMID:22717102

  4. Development of a behavior model of pain induced by experimental tooth movement in rats.

    PubMed

    Yang, Zhi; Luo, Wei; Hou, Jingqiu; Zhao, Zhihe; Jian, Fan; Wamalwa, Peter; Lai, Wenli; Wang, Jing; Wang, Yan; Liao, Zhenyu

    2009-08-01

    The mechanism of orthodontic pain and discomfort is poorly understood partly because of the limited number of animal behavioral models for pain assessment. This study aimed to develop a behavioral model for assessment of tooth-movement pain in rats using directed face-grooming activity. Male Sprague-Dawley rats weighing 200-300 g were used. They were videotaped on days 1, 3, 5, 7, and 14 after experimental tooth movement and their directed face-grooming behavior was evaluated. In addition, we also evaluated behavioral responses to the application of a progressively higher magnitude force and to multiple applications of an equal magnitude force. Finally, the effects of peripherally and systemically administered morphine and of the N-methyl-d-aspartate (NMDA) receptor antagonist, MK-801, on the behavioral responses were evaluated. The results indicated that time spent on directed face-grooming activity increased dramatically after initiating experimental tooth movement. The change concurred with the initial orthodontic pain response. This behavioral change was reproducible and was related to force magnitude. Application of both systemic and peripheral morphine and MK-801 could exert an analgesic effect on this pain model. These results suggest that directed face-grooming behavior can be a reliable measure for tooth-movement pain in rats, which could be widely used in investigating the orthodontic pain mechanism.

  5. A Quantitative Review of Ethnic Group Differences in Experimental Pain Response: Do Biology, Psychology and Culture Matter?

    PubMed Central

    Riley, Joseph L.; Williams, Ameenah K.K.; Fillingim, Roger B.

    2012-01-01

    Objective Pain is a subjectively complex and universal experience. We examine research investigating ethnic group differences in experimental pain response, and factors contributing to group differences. Method We conducted a systematic literature review and analysis of studies using experimental pain stimuli to assess pain sensitivity across multiple ethnic groups. Our search covered the period from 1944-2011, and utilized the PUBMED bibliographic database; a reference source containing over 17 million citations. We calculated effect sizes, identified ethnic/racial group categories, pain stimuli and measures, and examined findings regarding biopsychosociocultural factors contributing to ethnic/racial group differences. Results We found 472 studies investigating ethnic group differences and pain. Twenty-six of these met our review inclusion criteria of investigating ethnic group differences in experimental pain. The majority of studies included comparisons between African Americans (AA) and non-Hispanic Whites (NHW). There were consistently moderate to large effect sizes for pain tolerance across multiple stimulus modalities; African Americans demonstrated lower pain tolerance. For pain threshold, findings were generally in the same direction, but effect sizes were small to moderate across ethnic groups. Limited data were available for suprathreshold pain ratings. A subset of studies comparing NHW and other ethnic groups showed a variable range of effect sizes for pain threshold and tolerance. Conclusion There are potentially important ethnic/racial group differences in experimental pain perception. Elucidating ethnic group differences, has translational merit for culturally-competent clinical care and for addressing and reducing pain treatment disparities among ethnically/racially diverse groups. PMID:22390201

  6. Noneffect of manual needle acupuncture on experimental pain parameters in healthy young men.

    PubMed

    Micalos, Peter S; Pak, Sok Cheon

    2011-01-01

    The purpose of this study is to assess the effect of manual acupuncture on experimental pain parameters in healthy participants. The experimental design was a repeated-measures, three-group pre- and postprocedure. All subjects participated in a control, sham, and acupuncture procedure, separated by 1 week, in a counterbalanced sequence to forestall an order effect. Data were collected in a laboratory environment. The participants included 12 healthy young men (mean age 21.3 ± 2.6 years; height 183.8 ± 5 cm; weight 77.7 ± 9.5 kg). The control procedure comprised assessing the experimental pain parameters before and after a quiet rest for 20 minutes. The sham procedure was performed with the needle inserted bilaterally 1-1.5 cm outside each acupoint. The manual acupuncture procedure was performed at two bilateral acupoints of LI-4 (Large Intestine 4, Hegu) and ST-44 (Stomach 44, Nei Ting). Pain parameters assessed included the pain threshold, nociceptive reflex threshold, and nociceptive reflex amplitude. Repeated-measures analysis of variance between pre- and postcontrol, sham, and acupuncture procedures for pain threshold, nociceptive reflex threshold, and nociceptive reflex amplitude revealed no significant difference. Manual acupuncture at bilateral acupoints LI-4 and ST-44 did not show a change in pain threshold, nociceptive flexion reflex threshold, or the nociceptive reflex amplitude in healthy participants.

  7. TENS attenuates repetition-induced summation of activity-related pain following experimentally induced muscle soreness.

    PubMed

    Mankovsky-Arnold, Tsipora; Wideman, Timothy H; Larivière, Christian; Sullivan, Michael J L

    2013-11-01

    This study sought to determine whether repetition-induced summation of activity-related pain (RISP) could be demonstrated in healthy individuals in response to experimentally induced musculoskeletal pain. This study also assessed the effects of transcutaneous electrical nerve stimulation on RISP. The relation between the index of RISP and psychological factors such as catastrophizing and fear of pain was also explored. The sample consisted of 56 healthy (35 women, 21 men) participants who underwent 2 testing sessions, separated by 24 hours. In the first session, musculoskeletal pain was induced with a delayed-onset muscle soreness protocol. During the second session, participants were randomly assigned to the transcutaneous electrical nerve stimulation or placebo condition and were asked to rate their pain as they lifted a series of 18 weighted canisters. An index of RISP was derived as the change in pain ratings across repeated lifts. Approximately 25% of participants showed evidence of RISP. Results also revealed that transcutaneous electrical nerve stimulation attenuated the RISP effect. Psychological measures (fear of pain, catastrophizing) were not significantly correlated with the index of RISP, but the index of RISP was significantly correlated with a measure of physical tolerance. Discussion addresses the clinical implications of the findings as well as the potential mechanisms underlying RISP. This study showed that RISP could be demonstrated in healthy individuals in response to experimentally induced musculoskeletal pain with delayed-onset muscle soreness. Transcutaneous electrical nerve stimulation led to a significant reduction in RISP. Copyright © 2013 American Pain Society. Published by Elsevier Inc. All rights reserved.

  8. Comparison of location, depth, quality, and intensity of experimentally induced pain in 6 low back muscles.

    PubMed

    Tucker, Kylie J; Fels, Matthew; Walker, Scott R; Hodges, Paul W

    2014-09-01

    The pattern of pain originating from experimentally induced low back pain appears diffuse. This may be because sensory information from low back muscles converges, sensory innervation extends over multiple vertebral levels, or people have difficulty accurately representing the painful location on standardized pain maps. The aim of this study was to provide insight into the perception of pain from noxious stimulation of a range of low back muscles using novel depth and location measures. Hypertonic saline (1 mL, 7% NaCl) was injected into bellies of longissimus (LO), quadratus lumborum (QL), superficial multifidus (SM), and deep multifidus (DM) at the level of the fourth lumbar vertebrae (L4) and in SM and DM at L5 using ultrasound guidance over 6 sessions. Fifteen participants reported depth, location, intensity, size, and descriptive quality of pain throughout the painful period (∼14 min). Pain was reported deeper (P<0.04) for DML4/L5 compared with SML4/L5, LO and QL; more cranial for LO compared with DML4 and QL (P<0.01); more lateral for LO compared with DML4 (P<0.02); and more lateral for QL compared with all other muscles at L4 (P<0.0001). Pain intensity was higher in DML4/L5 than all other muscles (P<0.04) for ∼3 minutes. Descriptive qualities varied slightly between muscles. Depth and lateral position may be the most critical descriptors to determine the source of acute lumbar muscular pain. Overlapping regions of pain may be explained by convergence of receptive fields, innervation of multifidus fascicles at multiple lumbar segments, and convergence of sensory input from different muscles to the same sensory cell bodies as demonstrated in the lumbar spine of animal preparations.

  9. The effect of spinal manipulative therapy on experimentally induced pain: a systematic literature review

    PubMed Central

    2012-01-01

    Background Although there is evidence that spinal manipulative therapy (SMT) can reduce pain, the mechanisms involved are not well established. There is a need to review the scientific literature to establish the evidence-base for the reduction of pain following SMT. Objectives To determine if SMT can reduce experimentally induced pain, and if so, if the effect is i) only at the level of the treated spinal segment, ii) broader but in the same general region as SMT is performed, or iii) systemic. Design A systematic critical literature review. Methods A systematic search was performed for experimental studies on healthy volunteers and people without chronic syndromes, in which the immediate effect of SMT was tested. Articles selected were reviewed blindly by two authors. A summary quality score was calculated to indicate level of manuscript quality. Outcome was considered positive if the pain-reducing effect was statistically significant. Separate evidence tables were constructed with information relevant to each research question. Results were interpreted taking into account their manuscript quality. Results Twenty-two articles were included, describing 43 experiments, primarily on pain produced by pressure (n = 27) or temperature (n = 9). Their quality was generally moderate. A hypoalgesic effect was shown in 19/27 experiments on pressure pain, produced by pressure in 3/9 on pain produced by temperature and in 6/7 tests on pain induced by other measures. Second pain provoked by temperature seems to respond to SMT but not first pain. Most studies revealed a local or regional hypoalgesic effect whereas a systematic effect was unclear. Manipulation of a “restricted motion segment” (“manipulable lesion”) seemed not to be essential to analgesia. In relation to outcome, there was no discernible difference between studies with higher vs. lower quality scores. Conclusions These results indicate that SMT has a direct local/regional hypoalgesic effect on

  10. Inflammation-induced pain sensitization in men and women: does sex matter in experimental endotoxemia?

    PubMed Central

    Wegner, Alexander; Elsenbruch, Sigrid; Rebernik, Laura; Roderigo, Till; Engelbrecht, Elisa; Jäger, Marcus; Engler, Harald; Schedlowski, Manfred; Benson, Sven

    2015-01-01

    Abstract A role of the innate immune system is increasingly recognized as a mechanism contributing to pain sensitization. Experimental administration of the bacterial endotoxin lipopolysaccharide (LPS) constitutes a model to study inflammation-induced pain sensitization, but all existing human evidence comes from male participants. We assessed visceral and musculoskeletal pain sensitivity after low-dose LPS administration in healthy men and women to test the hypothesis that women show greater LPS-induced hyperalgesia compared with men. In this randomized, double-blind, placebo-controlled crossover study, healthy men (n = 20) and healthy women using oral contraceptives (n = 20) received an intravenous injection of 0.4 ng/kg body weight LPS or placebo. Pain sensitivity was assessed with established visceral and musculoskeletal pain models (ie, rectal pain thresholds; pressure pain thresholds for different muscle groups), together with a heartbeat perception (interoceptive accuracy) task. Plasma cytokines (tumor necrosis factor-α and interleukin-6) were measured along with state anxiety at baseline and up to 6-hour postinjection. Lipopolysaccharide application led to significant increases in plasma cytokines and state anxiety and decreased interoceptive awareness in men and women (P < 0.001, condition effects), with more pronounced LPS-induced cytokine increases in women (P < 0.05, interaction effects). Although both rectal and pressure pain thresholds were significantly decreased in the LPS condition (all P < 0.05, condition effect), no sex differences in endotoxin-induced sensitization were observed. In summary, LPS-induced systemic immune activation leads to visceral and musculoskeletal hyperalgesia, irrespective of biological sex. These findings support the broad applicability of experimental endotoxin administration as a translational preclinical model of inflammation-induced pain sensitization in both sexes. PMID:26058036

  11. Inflammation-induced pain sensitization in men and women: does sex matter in experimental endotoxemia?

    PubMed

    Wegner, Alexander; Elsenbruch, Sigrid; Rebernik, Laura; Roderigo, Till; Engelbrecht, Elisa; Jäger, Marcus; Engler, Harald; Schedlowski, Manfred; Benson, Sven

    2015-10-01

    A role of the innate immune system is increasingly recognized as a mechanism contributing to pain sensitization. Experimental administration of the bacterial endotoxin lipopolysaccharide (LPS) constitutes a model to study inflammation-induced pain sensitization, but all existing human evidence comes from male participants. We assessed visceral and musculoskeletal pain sensitivity after low-dose LPS administration in healthy men and women to test the hypothesis that women show greater LPS-induced hyperalgesia compared with men. In this randomized, double-blind, placebo-controlled crossover study, healthy men (n = 20) and healthy women using oral contraceptives (n = 20) received an intravenous injection of 0.4 ng/kg body weight LPS or placebo. Pain sensitivity was assessed with established visceral and musculoskeletal pain models (ie, rectal pain thresholds; pressure pain thresholds for different muscle groups), together with a heartbeat perception (interoceptive accuracy) task. Plasma cytokines (tumor necrosis factor-α and interleukin-6) were measured along with state anxiety at baseline and up to 6-hour postinjection. Lipopolysaccharide application led to significant increases in plasma cytokines and state anxiety and decreased interoceptive awareness in men and women (P < 0.001, condition effects), with more pronounced LPS-induced cytokine increases in women (P < 0.05, interaction effects). Although both rectal and pressure pain thresholds were significantly decreased in the LPS condition (all P < 0.05, condition effect), no sex differences in endotoxin-induced sensitization were observed. In summary, LPS-induced systemic immune activation leads to visceral and musculoskeletal hyperalgesia, irrespective of biological sex. These findings support the broad applicability of experimental endotoxin administration as a translational preclinical model of inflammation-induced pain sensitization in both sexes.

  12. Effect of transdermal opioids in experimentally induced superficial, deep and hyperalgesic pain.

    PubMed

    Andresen, T; Staahl, C; Oksche, A; Mansikka, H; Arendt-Nielsen, L; Drewes, A M

    2011-10-01

    Chronic pain and hyperalgesia can be difficult to treat with classical opioids acting predominately at the µ-opioid receptor. Buprenorphine and its active metabolite are believed to act through µ-, κ- and δ-receptors and may therefore possess different analgesic and anti-hyperalgesic effects compared with pure µ-receptor agonists, for example, fentanyl. Here, we have compared the analgesic and anti-hyperalgesic effects of buprenorphine and fentanyl. Twenty-two healthy volunteers were randomized to treatment with transdermal buprenorphine (20 µg·h(-1), 144 h), fentanyl (25 µg·h(-1), 72 h) or placebo patches in a double-blind, cross-over experimental pain study. The experimental pain tests (phasic pain, sensitization) involved pressure at the tibial bone, cutaneous electrical and thermal stimulation, intramuscular nerve growth factor, UVB light burn injury model and intradermal capsaicin-induced hyperalgesia. Pain testing was carried out at baseline, 24, 48, 72 and 144 h after application of the drugs. Compared with placebo, buprenorphine, but not fentanyl, significantly attenuated pressure at the tibial bone as well as pressure pain in the primary hyperalgesic area induced by UVB light The two drugs were equipotent and better than placebo against cutaneous thermal pain stimulation), but failed to show significant analgesic effect to cutaneous electrical stimulation, nerve growth factor-induced muscle soreness and to capsaicin-induced hyperalgesia. Buprenorphine, but not fentanyl, showed analgesic effects against experimentally induced, bone-associated pain and primary hyperalgesia compared with placebo. These tissue- and modality-differentiated properties may reflect the variable effects of opioid drugs observed in individual patients. © 2011 The Authors. British Journal of Pharmacology © 2011 The British Pharmacological Society.

  13. Attention to pain! A neurocognitive perspective on attentional modulation of pain in neuroimaging studies.

    PubMed

    Torta, D M; Legrain, V; Mouraux, A; Valentini, E

    2017-04-01

    Several studies have used neuroimaging techniques to investigate brain correlates of the attentional modulation of pain. Although these studies have advanced the knowledge in the field, important confounding factors such as imprecise theoretical definitions of attention, incomplete operationalization of the construct under exam, and limitations of techniques relying on measuring regional changes in cerebral blood flow have hampered the potential relevance of the conclusions. Here, we first provide an overview of the major theories of attention and of attention in the study of pain to bridge theory and experimental results. We conclude that load and motivational/affective theories are particularly relevant to study the attentional modulation of pain and should be carefully integrated in functional neuroimaging studies. Then, we summarize previous findings and discuss the possible neural correlates of the attentional modulation of pain. We discuss whether classical functional neuroimaging techniques are suitable to measure the effect of a fluctuating process like attention, and in which circumstances functional neuroimaging can be reliably used to measure the attentional modulation of pain. Finally, we argue that the analysis of brain networks and spontaneous oscillations may be a crucial future development in the study of attentional modulation of pain, and why the interplay between attention and pain, as examined so far, may rely on neural mechanisms shared with other sensory modalities. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. The Role of Coping and Race in Healthy Children’s Experimental Pain Responses

    PubMed Central

    Evans, Subhadra; Lu, Qian; Tsao, Jennie C. I.; Zelter, Lonnie K.

    2009-01-01

    This study examined the relationship between race, laboratory-based coping strategies and anticipatory anxiety and pain intensity for cold, thermal (heat) and pressure experimental pain tasks. Participants were 123 healthy children and adolescents, including 33 African Americans (51% female; mean age =13.9 years) and 90 Caucasians (50% female; mean age = 12.6 years). Coping in response to the cold task was assessed with the Lab Coping Style interview; based on their interview responses, participants were categorized as ‘attenders’ (i.e., those who focused on the task) vs. ‘distractors’ (i.e., those who distracted themselves during the task). Analysis of covariance (ANCOVA) revealed significant interactions between race (African-American vs. Caucasian) and lab-based coping style after controlling for sex, age and socioeconomic status. African-American children classified as attenders reported less anticipatory anxiety for the cold task and lower pain intensity for the cold, heat and pressure tasks compared to those categorized as distractors. For these pain outcomes, Caucasian children classified as distractors reported less anticipatory anxiety and lower pain intensity relative to those categorized as attenders. The findings point to the moderating effect of coping in the relationship between race and experimental pain sensitivity. PMID:20352035

  15. Adult Stem Cell as New Advanced Therapy for Experimental Neuropathic Pain Treatment

    PubMed Central

    Franchi, Silvia; Castelli, Mara; Amodeo, Giada; Niada, Stefania; Ferrari, Daniela; Vescovi, Angelo; Brini, Anna Teresa; Panerai, Alberto Emilio; Sacerdote, Paola

    2014-01-01

    Neuropathic pain (NP) is a highly invalidating disease resulting as consequence of a lesion or disease affecting the somatosensory system. All the pharmacological treatments today in use give a long lasting pain relief only in a limited percentage of patients before pain reappears making NP an incurable disease. New approaches are therefore needed and research is testing stem cell usage. Several papers have been written on experimental neuropathic pain treatment using stem cells of different origin and species to treat experimental NP. The original idea was based on the capacity of stem cell to offer a totipotent cellular source for replacing injured neural cells and for delivering trophic factors to lesion site; soon the researchers agreed that the capacity of stem cells to contrast NP was not dependent upon their regenerative effect but was mostly linked to a bidirectional interaction between the stem cell and damaged microenvironment resident cells. In this paper we review the preclinical studies produced in the last years assessing the effects induced by several stem cells in different models of neuropathic pain. The overall positive results obtained on pain remission by using stem cells that are safe, of easy isolation, and which may allow an autologous transplant in patients may be encouraging for moving from bench to bedside, although there are several issues that still need to be solved. PMID:25197647

  16. Adult stem cell as new advanced therapy for experimental neuropathic pain treatment.

    PubMed

    Franchi, Silvia; Castelli, Mara; Amodeo, Giada; Niada, Stefania; Ferrari, Daniela; Vescovi, Angelo; Brini, Anna Teresa; Panerai, Alberto Emilio; Sacerdote, Paola

    2014-01-01

    Neuropathic pain (NP) is a highly invalidating disease resulting as consequence of a lesion or disease affecting the somatosensory system. All the pharmacological treatments today in use give a long lasting pain relief only in a limited percentage of patients before pain reappears making NP an incurable disease. New approaches are therefore needed and research is testing stem cell usage. Several papers have been written on experimental neuropathic pain treatment using stem cells of different origin and species to treat experimental NP. The original idea was based on the capacity of stem cell to offer a totipotent cellular source for replacing injured neural cells and for delivering trophic factors to lesion site; soon the researchers agreed that the capacity of stem cells to contrast NP was not dependent upon their regenerative effect but was mostly linked to a bidirectional interaction between the stem cell and damaged microenvironment resident cells. In this paper we review the preclinical studies produced in the last years assessing the effects induced by several stem cells in different models of neuropathic pain. The overall positive results obtained on pain remission by using stem cells that are safe, of easy isolation, and which may allow an autologous transplant in patients may be encouraging for moving from bench to bedside, although there are several issues that still need to be solved.

  17. Space Adaptation Back Pain: A Retrospective Study

    NASA Technical Reports Server (NTRS)

    Kerstman, E. L.; Scheuring, R. A.; Barnes, M. G.; DeKorse, T. B.; Saile, L. G.

    2008-01-01

    Back pain is frequently reported by astronauts during the early phase of space flight as they adapt to the microgravity environment. However, the epidemiology of space adaptation back pain has not been well defined. The purpose of this retrospective study was to develop a case definition of space adaptation back pain, determine the incidence of space adaptation back pain, and determine the effectiveness of available treatments. Medical records from the Mercury, Apollo, Apollo-Soyuz Test Project (ASTP), Skylab, Mir, International Space Station (ISS), and Shuttle programs were reviewed. All episodes of in-flight back pain that met the criteria for space adaptation back pain were recorded. Pain characteristics, including intensity, location, and duration of the pain were noted. The effectiveness of specific treatments also was recorded. The incidence of space adaptation back pain among astronauts was determined to be 53% (384/722). Most of the affected astronauts reported mild pain (85%). Moderate pain was reported by 11% of the affected astronauts and severe pain was reported by only 4% of the affected astronauts. The most effective treatments were fetal positioning (91% effective) and the use of analgesic medications (85% effective). This retrospective study aids in the development of a case definition of space adaptation back pain and examines the epidemiology of space adaptation back pain. Space adaptation back pain is usually mild and self-limited. However, there is a risk of functional impairment and mission impact in cases of moderate or severe pain that do not respond to currently available treatments. Therefore, the development of preventive measures and more effective treatments should be pursued.

  18. Space Adaptation Back Pain: A Retrospective Study

    NASA Technical Reports Server (NTRS)

    Kerstman, E. L.; Scheuring, R. A.; Barnes, M. G.; DeKorse, T. B.; Saile, L. G.

    2008-01-01

    Back pain is frequently reported by astronauts during the early phase of space flight as they adapt to the microgravity environment. However, the epidemiology of space adaptation back pain has not been well defined. The purpose of this retrospective study was to develop a case definition of space adaptation back pain, determine the incidence of space adaptation back pain, and determine the effectiveness of available treatments. Medical records from the Mercury, Apollo, Apollo-Soyuz Test Project (ASTP), Skylab, Mir, International Space Station (ISS), and Shuttle programs were reviewed. All episodes of in-flight back pain that met the criteria for space adaptation back pain were recorded. Pain characteristics, including intensity, location, and duration of the pain were noted. The effectiveness of specific treatments also was recorded. The incidence of space adaptation back pain among astronauts was determined to be 53% (384/722). Most of the affected astronauts reported mild pain (85%). Moderate pain was reported by 11% of the affected astronauts and severe pain was reported by only 4% of the affected astronauts. The most effective treatments were fetal positioning (91% effective) and the use of analgesic medications (85% effective). This retrospective study aids in the development of a case definition of space adaptation back pain and examines the epidemiology of space adaptation back pain. Space adaptation back pain is usually mild and self-limited. However, there is a risk of functional impairment and mission impact in cases of moderate or severe pain that do not respond to currently available treatments. Therefore, the development of preventive measures and more effective treatments should be pursued.

  19. Pain behavior changes following disc puncture relate to nucleus pulposus rather than to the disc injury per se: an experimental study in rats.

    PubMed

    Nilsson, Elin; Nakamae, Toshio; Olmarker, Kjell

    2011-03-16

    It has previously been demonstrated that disc puncture in the rat induced changes in grooming and wet dog shakes, two behavioral changes that may be linked to discomfort and neuropathic pain. In this study the aim was to separate the effects of disc injury and the epidural presence of nucleus pulposus. Following anesthesia, the L4-5 disc was exposed using a dorsal approach. Ten rats received a superficial disc injury without nucleus pulposus leakage and ten rats received nucleus pulposus from a donor rat without disc injury. In ten animals the L4-5 disc was punctured using a ventral approach, with 10 corresponding controls. Spontaneous behavior was assessed after surgery. The data was matched to historical control of dorsal sham surgery and disc puncture. The study showed that the effects of nucleus pulposus were more pronounced than the effects induced by the disc injury. Ventral disc puncture did not induce any behavioral changes different from sham exposure. In conclusion, the data from the study indicate that behavioral changes induced by disc puncture are more likely to relate to the epidural presence of nucleus pulposus than the disc injury per se.

  20. Experimentally induced pain perception in men and women in the morning and evening.

    PubMed

    Koltyn, K F; Focht, B C; Ancker, J M; Pasley, J

    1999-01-01

    The literature regarding whether or not there are diurnal differences in pain perception in men and women is equivocal. The purpose of this study was to examine the influence of time of day on experimentally induced pain threshold in men and women. A secondary purpose was to measure selected psychological and physiological responses. Pressure (3000 gm force) was applied to the middle digit of the left forefinger for 2-min with the Forgione-Barber pain stimulator. Twenty-nine volunteers (women = 14; men = 15) completed two randomly assigned sessions between 6.00-8.00 in the AM and PM. Selected psychological variables (STAI,POMS) and physiological variables (BP, HR, TEMP) were assessed before application of the pressure stimulus. Data were analyzed with a 2x2 ANOVA. Results indicated that men had significantly higher (p<.05) systolic blood pressure and pain thresholds than women however, there was not a significant time of day effect for pain threshold. Significant time of day effects (p<.05) were found for systolic blood pressure and tympanic temperature. Heart rate, and tympanic temperature were found to be significantly higher (p<.05) in women in comparison to men. It is concluded that pain threshold did not differ in the AM and PM. Furthermore, men were found to have higher pain thresholds compared to the women.

  1. Experimental pain thresholds and plasma beta-endorphin levels during exercise.

    PubMed

    Droste, C; Greenlee, M W; Schreck, M; Roskamm, H

    1991-03-01

    Experimental pain thresholds (electrical intracutaneous finger and dental pulp stimulation) and plasma hormone levels (beta-endorphin, cortisol, and catecholamines) were measured in ten healthy sportive men before, during, and after progressively more strenuous physical exercise. In a double-blind study conducted on two different days, 20 mg of the opioid-antagonist naloxone or placebo was administered prior to exercise. A significant pain threshold elevation was found during exercise for finger (ANOVA, P less than 0.004) and dental pulp stimulation (P less than 0.01). Pain threshold elevation was most pronounced during maximal exertion, at which time the subjects reported the greatest subjective fatigue. Thresholds remained elevated 10-15 min after the end of exercise, and, 60 min after exercise, thresholds returned to baseline values. The subjective magnitude estimation of suprathreshold stimuli was significantly reduced (P less than 0.0001) 5-10 min after exercise. Plasma beta-endorphin, cortisol, and catecholamines increased significantly (P less than 0.0005, all values) during exercise. Plasma beta-endorphin levels did not correlate significantly with pain thresholds (r = -0.37, NS). Naloxone failed to affect pain thresholds, although beta-endorphin and cortisol increased significantly more (P less than 0.02) during exercise after naloxone. It is concluded that short-term, exhaustive physical exercise can evoke a transient elevation in pain thresholds. This exercise-induced elevation in pain threshold does not, however, appear to be directly related to plasma endorphin levels.

  2. Genetic predictors for acute experimental cold and heat pain sensitivity in humans

    PubMed Central

    Kim, H; Mittal, D P; Iadarola, M J; Dionne, R A

    2006-01-01

    Background The genetic contribution to pain sensitivity underlies a complex composite of parallel pain pathways, multiple mechanisms, and diverse inter‐individual pain experiences and expectations. Methods Variations for genes encoding receptors related to cold and heat sensation, such as transient receptor potential A subtype 1 (TRPA1), M subtype 8 (TRPM8), V subtype 1 (TRPV1), δ opioid receptor subtype 1 (OPRD1), catechol O‐methyltransferase (COMT), and fatty acid amide hydrolyase (FAAH), were investigated in four major ethnic populations. Results We defined 13 haplotype blocks in European Americans, seven blocks in African Americans, seven blocks in Hispanic subjects, and 11 blocks in Asian Americans. Further study in European American subjects found significant associations between short duration cold pain sensitivity and variations in TRPA1, COMT, and FAAH in a gender dependent manner. Our observations demonstrate that genetic variations in TRPA1, COMT, and FAAH contribute gender specifically to individual variations in short duration cold pain sensitivity in a European American cohort. Conclusions The effects of TRPA1 variations on experimental short duration heat pain sensitivity may contribute to inter‐individual variation in pain sensitivity in humans. PMID:16882734

  3. Suggestions to Reduce Clinical Fibromyalgia Pain and Experimentally Induced Pain Produce Parallel Effects on Perceived Pain but Divergent Functional MRI–Based Brain Activity

    PubMed Central

    Derbyshire, Stuart W.G.; Whalley, Matthew G.; Seah, Stanley T.H.; Oakley, David A.

    2017-01-01

    ABSTRACT Objective Hypnotic suggestion is an empirically validated form of pain control; however, the underlying mechanism remains unclear. Methods Thirteen fibromyalgia patients received suggestions to alter their clinical pain, and 15 healthy controls received suggestions to alter experimental heat pain. Suggestions were delivered before and after hypnotic induction with blood oxygen level–dependent (BOLD) activity measured concurrently. Results Across groups, suggestion produced substantial changes in pain report (main effect of suggestion, F2, 312 = 585.8; p < .0001), with marginally larger changes after induction (main effect of induction, F1, 312 = 3.6; p = .060). In patients, BOLD response increased with pain report in regions previously associated with pain, including thalamus and anterior cingulate cortex. In controls, BOLD response decreased with pain report. All changes were greater after induction. Region-of-interest analysis revealed largely linear patient responses with increasing pain report. Control responses, however, were higher after suggestion to increase or decrease pain from baseline. Conclusions Based on behavioral report alone, the mechanism of suggestion could be interpreted as largely similar regardless of the induction or type of pain experience. The functional magnetic resonance imaging data, however, demonstrated larger changes in brain activity after induction and a radically different pattern of brain activity for clinical pain compared with experimental pain. These findings imply that induction has an important effect on underlying neural activity mediating the effects of suggestion, and the mechanism of suggestion in patients altering clinical pain differs from that in controls altering experimental pain. Patient responses imply that suggestions altered pain experience via corresponding changes in pain-related brain regions, whereas control responses imply suggestion engaged cognitive control. PMID:27490850

  4. Antinociceptive Interaction of Tramadol with Gabapentin in Experimental Mononeuropathic Pain.

    PubMed

    Miranda, Hugo F; Noriega, Viviana; Prieto, Juan Carlos; Zanetta, Pilar; Castillo, Rodrigo; Aranda, Nicolás; Sierralta, Fernando

    2016-08-01

    Neuropathic pain is the result of injury to the nervous system, and different animal models have been established to meet the manifestations of neuropathy. The pharmacotherapy for neuropathic pain includes gabapentin and tramadol, but these are only partially effective when given alone. The aim of this study was to assess the antinociceptive interaction between both drugs using the isobolographic analysis and changes of the IL-1β concentration in a mouse model of neuropathic pain (partial sciatic nerve ligation or PSNL). The i.p. administration of gabapentin (5-100 mg/kg) or tramadol (12.5-100 mg/kg) displayed a dose-dependent antinociception in the hot plate assay of PSNL mice, and effects induced by gabapentin with tramadol were synergistic. Administration of gabapentin or tramadol reversed significantly the increase in the concentration of IL-1β induced by PSNL after either 7 or 14 days and their combination was significantly more potent in reversing the elevated concentration of IL-1β. The synergism obtained by the co-administration of gabapentin and tramadol is proposed to result from action on different mechanisms in pain pathways. Gabapentin or tramadol or their combination modulates the expression of pro-inflammatory cytokine, IL-1β, in a model of mice PSNL which could be due to an inhibition of glial function. © 2016 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).

  5. Comparison of acceptance and distraction strategies in coping with experimentally induced pain

    PubMed Central

    Moore, Hazel; Stewart, Ian; Barnes-Holmes, Dermot; Barnes-Holmes, Yvonne; McGuire, Brian E

    2015-01-01

    Background This study compared an acceptance-based strategy with a control-based strategy (distraction) in terms of the ability of participants to tolerate a painful stimulus, across two experiments. In addition, participants were either actively encouraged, or not, to link pain tolerance with pursuit of valued goals to examine the impact of pursuing a personally meaningful goal or value on the extent to which pain will be tolerated. Methods Participants in experiment 1 (n=41) and experiment 2 (n=52) were equally assigned to acceptance or distraction protocols. Further, half the participants in each group generated examples from their own lives in which they had pursued a valued objective, while the other half did not. In experiment 2, the values focus was enhanced to examine the impact on pain tolerance. Results There were no significant differences overall between the acceptance and distraction groups on pain tolerance in either experiment. However, in experiment 2, individuals classified as accepting in terms of general coping style and who were assigned to the acceptance strategy showed significantly better pain tolerance than accepting individuals who were in the distraction condition. Across both experiments, those with strong goal-driven values in both protocols were more tolerant of pain. Participants appeared to have more difficulty adhering to acceptance than to distraction as a strategy. Conclusion Acceptance may be associated with better tolerance of pain, but may also be more difficult to operationalize than distraction in experimental studies. Matching coping style and coping strategy may be most effective, and enhancement of goal-driven values may assist in pain coping. PMID:25834464

  6. Comparison of acceptance and distraction strategies in coping with experimentally induced pain.

    PubMed

    Moore, Hazel; Stewart, Ian; Barnes-Holmes, Dermot; Barnes-Holmes, Yvonne; McGuire, Brian E

    2015-01-01

    This study compared an acceptance-based strategy with a control-based strategy (distraction) in terms of the ability of participants to tolerate a painful stimulus, across two experiments. In addition, participants were either actively encouraged, or not, to link pain tolerance with pursuit of valued goals to examine the impact of pursuing a personally meaningful goal or value on the extent to which pain will be tolerated. Participants in experiment 1 (n=41) and experiment 2 (n=52) were equally assigned to acceptance or distraction protocols. Further, half the participants in each group generated examples from their own lives in which they had pursued a valued objective, while the other half did not. In experiment 2, the values focus was enhanced to examine the impact on pain tolerance. There were no significant differences overall between the acceptance and distraction groups on pain tolerance in either experiment. However, in experiment 2, individuals classified as accepting in terms of general coping style and who were assigned to the acceptance strategy showed significantly better pain tolerance than accepting individuals who were in the distraction condition. Across both experiments, those with strong goal-driven values in both protocols were more tolerant of pain. Participants appeared to have more difficulty adhering to acceptance than to distraction as a strategy. Acceptance may be associated with better tolerance of pain, but may also be more difficult to operationalize than distraction in experimental studies. Matching coping style and coping strategy may be most effective, and enhancement of goal-driven values may assist in pain coping.

  7. Parenting in the context of chronic pain: a controlled study of parents with chronic pain.

    PubMed

    Wilson, Anna C; Fales, Jessica L

    2015-08-01

    This study aims to describe what adults with chronic pain experience in their role as parents, utilizing quantitative and qualitative methods. The first aim was to compare parents with chronic pain to parents without chronic pain on perceptions of their adolescent's pain, parental response to pain, and catastrophizing beliefs about pain. The study also examined predictors of parental protective behaviors, and examined whether these associations differed by study group. Parents with chronic pain (n=58) and parents without chronic pain (n=72) participated, and completed questionnaire measures of pain characteristics and pain interference, as well as measures of parental catastrophizing and protective pain responses. Parents with chronic pain also completed a structured interview about their experience of being a parent. Interview responses were videotaped and subsequently coded for content. Compared with controls, parents with chronic pain endorsed more pain in their adolescents, and were more likely to catastrophize about their adolescent's pain and respond with protective behaviors. Parent's own pain interference and the perception of higher pain in their adolescent was associated with increased protective parenting in the chronic pain group. Qualitative coding revealed a number of areas of common impact of chronic pain on parenting. Chronic pain impacts everyday parenting activities and emotions, and impacts pain-specific parent responses that are known to be related to increased pain and pain catastrophizing in children and adolescents. Parents with chronic pain might benefit from interventions that address potential parenting difficulties, and might improve outcomes for their children.

  8. The language of pain: A short study.

    PubMed

    Rathnam, Arun; Madan, Nidhi; Madan, Neeti

    2010-07-01

    Pain perception is a very controversial topic in child patients. It is affected by various factors such as fear, anxiety, previous experiences, parental factors, and pain threshold. The communication of such pain by the child to the parent is also very confusing with children having rudimentary and developing communication skills. A study to evaluate the pain perception of children and the parental understanding of the children's pain would be helpful in this scenario. The effect on behavior due to pain is also attempted in this particular study. A cross-sectional study of 100 children aged between 5-13 years accompanied by either parent was performed. Data collection was done with the help of questionnaires, which assessed the parental understanding of the child's pain. Pain perception recording was done with the Visual Analog Scale of Faces (VASOF). The behavior of the child was noted using the Frankl's behavior rating scale. Data was collated and statistical analysis was performed using the SPSS (version 10) software. The results show that parental factors such as education, work culture, influence parental understanding of pain. VASOF proves to be a reliable tool for pain perception in children. Behavior of the child shows a positive correlation to pain perception.

  9. Complex regional pain syndrome (CRPS) or continuous unilateral distal experimental pain stimulation in healthy subjects does not bias visual attention towards one hemifield.

    PubMed

    Filippopulos, Filipp M; Grafenstein, Jessica; Straube, Andreas; Eggert, Thomas

    2015-11-01

    In natural life pain automatically draws attention towards the painful body part suggesting that it interacts with different attentional mechanisms such as visual attention. Complex regional pain syndrome (CRPS) patients who typically report on chronic distally located pain of one extremity may suffer from so-called neglect-like symptoms, which have also been linked to attentional mechanisms. The purpose of the study was to further evaluate how continuous pain conditions influence visual attention. Saccade latencies were recorded in two experiments using a common visual attention paradigm whereby orientating saccades to cued or uncued lateral visual targets had to be performed. In the first experiment saccade latencies of healthy subjects were measured under two conditions: one in which continuous experimental pain stimulation was applied to the index finger to imitate a continuous pain situation, and one without pain stimulation. In the second experiment saccade latencies of patients suffering from CRPS were compared to controls. The results showed that neither the continuous experimental pain stimulation during the experiment nor the chronic pain in CRPS led to an unilateral increase of saccade latencies or to a unilateral increase of the cue effect on latency. The results show that unilateral, continuously applied pain stimuli or chronic pain have no or only very limited influence on visual attention. Differently from patients with visual neglect, patients with CRPS did not show strong side asymmetries of saccade latencies or of cue effects on saccade latencies. Thus, neglect-like clinical symptoms of CRPS patients do not involve the allocation of visual attention.

  10. A practical guide and perspectives on the use of experimental pain modalities with children and adolescents

    PubMed Central

    Birnie, Kathryn A; Caes, Line; Wilson, Anna C; Williams, Sara E; Chambers, Christine T

    2014-01-01

    SUMMARY Use of experimental pain is vital for addressing research questions that would otherwise be impossible to examine in the real world. Experimental induction of pain in children is highly scrutinized given the potential for harm and lack of direct benefit to a vulnerable population. However, its use has critically advanced our understanding of the mechanisms, assessment and treatment of pain in both healthy and chronically ill children. This article introduces various experimental pain modalities, including the cold pressor task, the water load symptom provocation test, thermal pain, pressure pain and conditioned pain modulation, and discusses their application for use with children and adolescents. It addresses practical implementation and ethical issues, as well as the advantages and disadvantages offered by each task. The incredible potential for future research is discussed given the array of experimental pain modalities now available to pediatric researchers. PMID:24641434

  11. Adaptability to pain is associated with potency of local pain inhibition, but not conditioned pain modulation: a healthy human study.

    PubMed

    Zheng, Zhen; Wang, Kelun; Yao, Dongyuan; Xue, Charlie C L; Arendt-Nielsen, Lars

    2014-05-01

    This study investigated the relationship between pain sensitivity, adaptability, and potency of endogenous pain inhibition, including conditioned pain modulation (CPM) and local pain inhibition. Forty-one healthy volunteers (20 male, 21 female) received conditioning stimulation (CS) over 2 sessions in a random order: tonic heat pain (46 °C) on the right leg for 7 minutes and cold pressor pain (1 °C to 4 °C) on the left hand for 5 minutes. Participants rated the intensity of pain continuously using a 0 to 10 electronic visual analogue scale. The primary outcome measures were pressure pain thresholds (PPT) measured at the heterotopic and homotopic location to the CS sites before, during, and 20 minutes after CS. Two groups of participants, pain adaptive and pain nonadaptive, were identified based on their response to pain in the cold pressor test. Pain-adaptive participants showed a pain reduction between peak pain and pain at end of the test by at least 2 of 10 (n=16); whereas the pain-nonadaptive participants reported unchanged peak pain during 5-minute CS (n=25). Heterotopic PPTs during the CS did not differ between the 2 groups. However, increased homotopic PPTs measured 20 minutes after CS correlated with the amount of pain reduction during CS. These results suggest that individual sensitivity and adaptability to pain does not correlate with the potency of CPM. Adaptability to pain is associated with longer-lasting local pain inhibition.

  12. Spinal segmental and supraspinal mechanisms underlying the pain-relieving effects of spinal cord stimulation: an experimental study in a rat model of neuropathy.

    PubMed

    Barchini, J; Tchachaghian, S; Shamaa, F; Jabbur, S J; Meyerson, B A; Song, Z; Linderoth, B; Saadé, N E

    2012-07-26

    Spinal cord stimulation (SCS) may alleviate certain forms of neuropathic pain; its mechanisms of action are, however, not fully understood. Previous studies have mainly been focused onto segmental spinal mechanisms, though there is evidence indicating a supraspinal involvement. This study aims to evaluate the relative importance of segmental and supraspinal mechanisms related to the activation of the dorsal columns (DCs). Rats were used to induce the spared nerve injury neuropathy and simultaneously subjected to chronic bilateral DC lesions at the C6-C8 level. Two pairs of miniature electrodes were implanted in each animal, with a monopolar system placed in the dorsal epidural space at a low thoracic level (below lesion) and a bipolar system placed onto the dorsal column nuclei (above lesion). Stimulation (50 Hz, 0.2 ms, 2-4V, 5 min) was applied via either type of electrodes, and tests for sensitivity to tactile and thermal stimuli were used to assess its inhibitory effects. Various receptor antagonists {bicuculline (GABA(A)), saclofen (GABA(B)), ketanserine (5HT(2)), methysergide (5HT(1-2)), phentolamine (α-adrenergic), propranolol (β-adrenergic), sulpiride (D(2)/D(3) dopamine) or saline were injected prior to the SCS. Rostral and caudal stimulations produced a comparable inhibition of neuropathic manifestations, and these effects were attenuated by about 50% after DC lesions. Pretreatment with the various receptor antagonists differentially influenced the effects of rostral and caudal stimulation. Our findings suggest that both supraspinal and segmental mechanisms are activated by SCS, and that in this model with DC lesions, rostral and caudal stimulations may activate different synaptic circuitries and transmitter systems.

  13. Preoccupation in an early-romantic relationship predicts experimental pain relief.

    PubMed

    Nilakantan, Aneesha; Younger, Jarred; Aron, Arthur; Mackey, Sean

    2014-06-01

    Individuals involved in the early stages of a passionate romantic relationship can be consumed by the experience and report emotional dependence and constant focus on their romantic partner. A few studies have shown that viewing pictures of a romantic partner can significantly reduce experimental pain. The strength of the effect, however, varies substantially between individuals. To study why some individuals experience significant pain reduction when looking at a picture of their partner, we examined partner preoccupation. We hypothesized that a greater degree of preoccupation in the early stages of a romantic relationship would be associated with greater analgesia during a pain induction task. Participants were shown pictures of their romantic partner or an equally attractive and familiar acquaintance while exposed to low, moderate, or high levels of thermal pain. Participants were also asked to rate how much time they spent thinking about their romantic partner during an average day. Degree of preoccupation was defined as the percentage of time participants spent thinking about their partner on an average day. In two separate experiments, viewing pictures of a romantic partner produced an analgesic effect. The degree of pain relief was positively correlated with partner preoccupation. The results suggest that preoccupation with a romantic partner during early stage romantic love is a predictor of pain relief when viewing pictures of the beloved. Wiley Periodicals, Inc.

  14. Preoccupation in an early-romantic relationship predicts experimental pain relief

    PubMed Central

    Nilakantan, Aneesha; Younger, Jarred; Aron, Arthur; Mackey, Sean

    2014-01-01

    Objective Individuals involved in the early stages of a passionate romantic relationship can be consumed by the experience and report emotional dependence and constant focus on their romantic partner. A few studies have shown that viewing pictures of a romantic partner can significantly reduce experimental pain. The strength of the effect, however, varies substantially between individuals. To study why some individuals experience significant pain reduction when looking at a picture of their partner, we examined partner preoccupation. We hypothesized that a greater degree of preoccupation in the early stages of a romantic relationship would be associated with greater analgesia during a pain induction task. Methods Participants were shown pictures of their romantic partner or an equally attractive and familiar acquaintance while exposed to low, moderate or high levels of thermal pain. Participants were also asked to rate how much time they spent thinking about their romantic partner during an average day. Degree of preoccupation was defined as the percentage of time participants spent thinking about their partner on an average day. Results In two separate experiments, viewing pictures of a romantic partner produced an analgesic effect. The degree of pain relief was positively correlated with partner preoccupation. The results suggest that preoccupation with a romantic partner during early stage romantic love is a predictor of pain relief when viewing pictures of the beloved. PMID:24716721

  15. Peripheral opioid analgesia in experimental human pain models.

    PubMed

    Tegeder, Irmgard; Meier, Silke; Burian, Maria; Schmidt, Helmut; Geisslinger, Gerd; Lötsch, Jörn

    2003-05-01

    This placebo-controlled, double-blind crossover study assessed whether exclusive activation of peripheral opioid receptors results in significant pain reduction. To achieve opioid activity restricted to the periphery, we used a short-term (2 h) low dose infusion of morphine-6-beta-glucuronide (M6G) because M6G does not pass the blood-brain barrier during this time in amounts sufficient to induce CNS effects. The lack of central opioid effects of M6G was confirmed by a lack of change of the pupil size and absence of other opioid-related CNS effects. As a positive control, morphine was infused at a dosage that definitely produced CNS effects. This was evident by a rapid decrease of the pupil size and by other typical opioid-related side effects including nausea, vomiting, itchiness, hiccup and sedation. Three different pain models were employed to evaluate the analgesic effects: (i) cutaneous inflammatory hyperalgesia induced by briefly freezing a small skin area to -30 degrees C ('freeze lesion'); (ii) muscle hyperalgesia induced by a series of concentric and eccentric muscle contractions (DOMS model; delayed onset of muscle soreness); and (iii) pain induced by electrical current (5 Hz sinus stimuli of 0-10 mA). M6G significantly reduced cutaneous hyperalgesia in the 'freeze lesion' model as assessed with von Frey hairs. It also reduced muscle hyperalgesia in the DOMS model. Electrical pain, however, was not affected by M6G. Morphine was significantly more active in the 'freeze lesion' and DOMS model, and also significantly increased the electrical pain threshold and tolerance. Subcutaneous tissue concentrations of M6G and morphine as assessed with microdialysis were about half those of the respective plasma concentrations. The results of the study indicate that M6G has antihyperalgesic effects in inflammatory pain through activation of peripheral opioid receptors. Since this occurs at concentrations that do not cause central opioid effects, M6G might be useful as a

  16. Endogenous Opioid Antagonism in Physiological Experimental Pain Models: A Systematic Review

    PubMed Central

    Werner, Mads U.; Pereira, Manuel P.; Andersen, Lars Peter H.; Dahl, Jørgen B.

    2015-01-01

    Opioid antagonists are pharmacological tools applied as an indirect measure to detect activation of the endogenous opioid system (EOS) in experimental pain models. The objective of this systematic review was to examine the effect of mu-opioid-receptor (MOR) antagonists in placebo-controlled, double-blind studies using ʻinhibitoryʼ or ʻsensitizingʼ, physiological test paradigms in healthy human subjects. The databases PubMed and Embase were searched according to predefined criteria. Out of a total of 2,142 records, 63 studies (1,477 subjects [male/female ratio = 1.5]) were considered relevant. Twenty-five studies utilized ʻinhibitoryʼ test paradigms (ITP) and 38 studies utilized ʻsensitizingʼ test paradigms (STP). The ITP-studies were characterized as conditioning modulation models (22 studies) and repetitive transcranial magnetic stimulation models (rTMS; 3 studies), and, the STP-studies as secondary hyperalgesia models (6 studies), ʻpainʼ models (25 studies), summation models (2 studies), nociceptive reflex models (3 studies) and miscellaneous models (2 studies). A consistent reversal of analgesia by a MOR-antagonist was demonstrated in 10 of the 25 ITP-studies, including stress-induced analgesia and rTMS. In the remaining 14 conditioning modulation studies either absence of effects or ambiguous effects by MOR-antagonists, were observed. In the STP-studies, no effect of the opioid-blockade could be demonstrated in 5 out of 6 secondary hyperalgesia studies. The direction of MOR-antagonist dependent effects upon pain ratings, threshold assessments and somatosensory evoked potentials (SSEP), did not appear consistent in 28 out of 32 ʻpainʼ model studies. In conclusion, only in 2 experimental human pain models, i.e., stress-induced analgesia and rTMS, administration of MOR-antagonist demonstrated a consistent effect, presumably mediated by an EOS-dependent mechanisms of analgesia and hyperalgesia. PMID:26029906

  17. Deciphering the Temporal Link between Pain and Sleep in a Heterogeneous Chronic Pain Patient Sample: A Multilevel Daily Process Study

    PubMed Central

    Tang, Nicole K.Y.; Goodchild, Claire E.; Sanborn, Adam N.; Howard, Jonathan; Salkovskis, Paul M.

    2012-01-01

    Objectives: Because insomnia is a common comorbidity of chronic pain, scientific and clinical interest in the relationship of pain and sleep has surged in recent years. Although experimental studies suggest a sleep-interfering property of pain and a pain-enhancing effect of sleep deprivation/fragmentation, the temporal association between pain and sleep as experienced by patients is less understood. The current study was conducted to examine the influence of presleep pain on subsequent sleep and sleep on pain reports the next day, taking into consideration other related psychophysiologic variables such as mood and arousal. Design: A daily process study, involving participants to monitor their pain, sleep, mood, and presleep arousal for 1 wk. Multilevel modeling was used to analyze the data. Setting: In the patients' natural living and sleeping environment. Patients: One hundred nineteen patients (73.9% female, mean age = 46 years) with chronic pain and concomitant insomnia. Measurement: An electronic diary was used to record patients' self-reported sleep quality/efficiency and ratings of pain, mood, and arousal at different times of the day; actigraphy was also used to provide estimates of sleep efficiency. Results: Results indicated that presleep pain was not a reliable predictor of subsequent sleep. Instead, sleep was better predicted by presleep cognitive arousal. Although sleep quality was a consistent predictor of pain the next day, the pain-relieving effect of sleep was only evident during the first half of the day. Conclusions: These findings challenge the often-assumed reciprocal relationship between pain and sleep and call for a diversification in thinking of the daily interaction of these 2 processes. Citation: Tang NKY; Goodchild CE; Sanborn AN; Howard J; Salkovskis PM. Deciphering the temporal link between pain and sleep in a heterogeneous chronic pain patient sample: a multilevel daily process study. SLEEP 2012;35(5):675-687. PMID:22547894

  18. Pain management in trauma: A review study

    PubMed Central

    Ahmadi, Alireza; Bazargan-Hejazi, Shahrzad; Heidari Zadie, Zahra; Euasobhon, Pramote; Ketumarn, Penkae; Karbasfrushan, Ali; Amini-Saman, Javad; Mohammadi, Reza

    2016-01-01

    Abstract: Background: Pain in trauma has a role similar to the double-edged sword. On the one hand, pain is a good indicator to determine the severity and type of injury. On the other hand, pain can induce sever complications and it may lead to further deterioration of the patient. Therefore, knowing how to manage pain in trauma patients is an important part of systemic approach in trauma. The aim of this manuscript is to provide information about pain management in trauma in the Emergency Room settings. Methods: In this review we searched among electronic and manual documents covering a 15-yr period between 2000 and 2016. Our electronic search included Pub Med, Google scholar, Web of Science, and Cochrane databases. We looked for articles in English and in peer-reviewed journals using the following keywords: acute pain management, trauma, emergency room and injury. Results: More than 3200 documents were identified. After screening based on the study inclusion criteria, 560 studies that had direct linkage to the study aim were considered for evaluation based World Health Organization (WHO) pain ladder chart. Conclusions: To provide adequate pain management in trauma patients require: adequate assessment of age-specific pharmacologic pain management; identification of adequate analgesic to relieve moderate to severe pain; cognizance of serious adverse effects of pain medications and weighting medications against their benefits, and regularly reassessing patients and reevaluating their pain management regimen. Patient-centered trauma care will also require having knowledge of barriers to pain management and discussing them with the patient and his/her family to identify solutions. PMID:27414816

  19. Viewing Pictures of a Romantic Partner Reduces Experimental Pain: Involvement of Neural Reward Systems

    PubMed Central

    Younger, Jarred; Aron, Arthur; Parke, Sara; Chatterjee, Neil; Mackey, Sean

    2010-01-01

    The early stages of a new romantic relationship are characterized by intense feelings of euphoria, well-being, and preoccupation with the romantic partner. Neuroimaging research has linked those feelings to activation of reward systems in the human brain. The results of those studies may be relevant to pain management in humans, as basic animal research has shown that pharmacologic activation of reward systems can substantially reduce pain. Indeed, viewing pictures of a romantic partner was recently demonstrated to reduce experimental thermal pain. We hypothesized that pain relief evoked by viewing pictures of a romantic partner would be associated with neural activations in reward-processing centers. In this functional magnetic resonance imaging (fMRI) study, we examined fifteen individuals in the first nine months of a new, romantic relationship. Participants completed three tasks under periods of moderate and high thermal pain: 1) viewing pictures of their romantic partner, 2) viewing pictures of an equally attractive and familiar acquaintance, and 3) a word-association distraction task previously demonstrated to reduce pain. The partner and distraction tasks both significantly reduced self-reported pain, although only the partner task was associated with activation of reward systems. Greater analgesia while viewing pictures of a romantic partner was associated with increased activity in several reward-processing regions, including the caudate head, nucleus accumbens, lateral orbitofrontal cortex, amygdala, and dorsolateral prefrontal cortex – regions not associated with distraction-induced analgesia. The results suggest that the activation of neural reward systems via non-pharmacologic means can reduce the experience of pain. PMID:20967200

  20. REPEATED EXPOSURE TO EXPERIMENTAL PAIN DIFFERENTIATES COMBAT TBI WITH AND WITHOUT PTSD.

    PubMed

    Strigo, Irina A; Spadoni, Andrea D; Inslicht, Sabra S; Simmons, Alan N

    2017-09-20

    Mild traumatic brain injury(mTBI) and posttraumatic stress disorder(PTSD) are highly comorbid conditions that often co-occur with chronic pain. We have shown that women with PTSD following intimate partner violence show attenuated brain response to repeated experimental pain that was related to symptoms of avoidance. The aim of this study was to extend our prior findings to males with combat trauma and to examine brain response to experimental pain in men with and without PTSD who sustained mTBI during combat. Seventy male Veterans performed an experimental pain paradigm during fMRI. Of the 70 total subjects, 46 self-reported a history of mTBI during combat(46/70). Of those with mTBI, 26 also met criteria for PTSD(26/46) .  As in our prior study, we examined change in brain activity to repeated heat pain with linear mixed effects modeling for group by administration interaction effects. We observed a significant group by administration interaction to repeated heat pain within insular, frontal and parietal cortices such that the control group showed increased activation over time, while mTBI groups(mTBI-only, mTBI+PTSD) showed decreased activation within bilateral anterior insulas(AI) between administrations. Importantly, change in the right AI response was inversely correlated with avoidance symptoms, but only in those with co-morbid mTBI+PTSD. Furthermore, in the comorbid group greater AI attenuation was associated with decreased connectivity with anterior cingulate(ACC). The current study provides further evidence that repeated exposure to brief painful stimuli results in attenuation of insula activation over time in traumatized individuals. Furthermore, in PTSD, AI shows greatest attenuation in those with the highest level of avoidance - a finding that was replicated across diverse samples.  Thus, this mechanism may be a generalized mechanism of maladaptive response to experimental pain in those with significant trauma.

  1. The effect of cognitive bias modification for interpretation on avoidance of pain during an acute experimental pain task.

    PubMed

    Jones, Emma Blaisdale; Sharpe, Louise

    2014-08-01

    Research confirms that patients with chronic pain show a tendency to interpret ambiguous stimuli as pain related. However, whether modifying these interpretive pain biases impacts pain outcomes is unknown. This study aimed to demonstrate that interpretation biases towards pain can be modified, and that changing these biases influences pain outcomes in the cold pressor task. One hundred and six undergraduate students were randomly allocated to receive either threatening or reassuring information regarding the cold pressor. They also were randomly allocated to 1 of 2 conditions in the Ambiguous Scenarios Task, in which they were trained to have either a threatening interpretation of pain (pain bias condition) or a nonthreatening interpretation of pain (no pain bias condition). Therefore, the study had a 2 (threat/reassuring)×2 (pain bias/no pain bias) design. Analyses showed that a bias was induced contingent on condition, and that the threat manipulation was effective. Participants in the pain bias condition hesitated more before doing the cold pressor task than those in the no pain bias condition, as did those in the threat compared with the reassurance condition. The major finding was that interpretive bias mediated the relationship between bias condition and hesitance time, supporting the causal role of interpretive biases for avoidance behaviors in current chronic pain models. No differences were found on other pain outcomes regarding bias or threat, and the efficacy of the bias modification was not impacted by different levels of threat. These results suggest that cognitive bias modification should be further explored as a potential intervention in pain.

  2. Statins alleviate experimental nerve injury-induced neuropathic pain.

    PubMed

    Shi, Xiang Qun; Lim, Tony K Y; Lee, Seunghwan; Zhao, Yuan Qing; Zhang, Ji

    2011-05-01

    The statins are a well-established class of drugs that lower plasma cholesterol levels by inhibiting HMG-CoA (3-hydroxy-3-methyl-glutaryl-coenzyme A) reductase. They are widely used for the treatment of hypercholesterolemia and for the prevention of coronary heart disease. Recent studies suggest that statins have anti-inflammatory effects beyond their lipid-lowering properties. We sought to investigate whether statins could affect neuropathic pain by mediating nerve injury-associated inflammatory responses. The effects of hydrophilic rosuvastatin and lipophilic simvastatin were examined in the mouse partial sciatic nerve ligation model. Systemic daily administration of either statin from days 0 to 14 completely prevented the development of mechanical allodynia and thermal hyperalgesia. When administered from days 8 to 14 after injury, both statins dose-dependently reduced established hypersensitivity. After treatment, the effects of the statins were washed out within 2 to 7 days, depending on dose. Effects of both statins in alleviating mechanical allodynia were further confirmed in a different injury-associated neuropathic pain model, mental nerve chronic constriction, in rats. Both statins were able to abolish interleukin-1β expression in sciatic nerve triggered by nerve ligation. Additionally, quantitative analysis with Iba-1 and glial fibrillary acid protein immunoreactivity demonstrated that rosuvastatin and simvastatin significantly reduced the spinal microglial and astrocyte activation produced by sciatic nerve injury. The increase of interleukin-1β mRNA in the ipsilateral side of spinal cords was also reduced by the treatment of either statin. We identified a potential new application of statins in the treatment of neuropathic pain. The pain-alleviating effects of statins are likely attributable to their immunomodulatory effects.

  3. Pain empathy in schizophrenia: an fMRI study.

    PubMed

    Horan, William P; Jimenez, Amy M; Lee, Junghee; Wynn, Jonathan K; Eisenberger, Naomi I; Green, Michael F

    2016-05-01

    Although it has been proposed that schizophrenia is characterized by impaired empathy, several recent studies found intact neural responses on tasks measuring the affective subdomain of empathy. This study further examined affective empathy in 21 schizophrenia outpatients and 21 healthy controls using a validated pain empathy paradigm with two components: (i) observing videos of people described as medical patients who were receiving a painful sound stimulation treatment; (ii) listening to the painful sounds (to create regions of interest). The observing videos component incorporated experimental manipulations of perspective taking (instructions to imagine 'Self' vs 'Other' experiencing pain) and cognitive appraisal (information about whether treatment was 'Effective' vs 'Not Effective'). When considering activation across experimental conditions, both groups showed similar dorsal anterior cingulate cortex (dACC) and anterior insula (AI) activation while merely observing others in pain. However, there were group differences associated with perspective taking: controls showed relatively greater dACC and AI activation for the Self vs Other contrast whereas patients showed relatively greater activation in these and additional regions for the Other vs Self contrast. Although patients demonstrated grossly intact neural activity while observing others in pain, they showed more subtle abnormalities when required to toggle between imagining themselves vs others experiencing pain. © The Author (2016). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

  4. [Multicenter study of pain assessment in hospitals].

    PubMed

    Vallano, A; Payrulet, P; Malouf, J; Baños, J E

    2007-03-01

    To evaluate the recording of pain intensity in hospital charts. A cross-sectional study was carried out in 15 hospitals in a sample of admitted patients with pain. Clinical data, including pain intensity, were gathered from the hospital records. Multiple analysis of variance was used to identify factors related to the intensity of pain recorded in the patients' charts. A total of 1038 patients with a mean (SD) age of 56.1 (18.9) years were included. Pain intensity was noted in the charts of 47.9% (95% confidence interval [CI], 44.9%-50.9%) of the patients. Pain intensity had been noted for 68.9% (95% CI, 61.4%-76.4%) of the patients with cancer, 43% (95% CI, 38.2%-47.8%) of postoperative patients, 38.2% (95% CI, 35%-41.4%) of trauma patients, and 26.6% (95% CI, 16.9%-36.3%) of postpartum women. There was great interhospital variability. Factors associated with the recording of pain intensity in medical charts were hospital characteristics (large hospitals, teaching hospitals, hospitals and internal medicine and surgical specialities) and type of patient (cancer and trauma cases and patients reporting pain to the staff). There is inadequate written recording of intensity of pain in hospitals, even though there is considerable interhospital variation. Pain intensity assessment and recording is an indicator of quality of health care and should become a routine practice in hospital health care.

  5. The genetic influences on oxycodone response characteristics in human experimental pain.

    PubMed

    Olesen, Anne E; Sato, Hiroe; Nielsen, Lecia M; Staahl, Camilla; Droney, Joanne; Gretton, Sophy; Branford, Ruth; Drewes, Asbjørn M; Arendt-Nielsen, Lars; Riley, Julia; Ross, Joy

    2015-08-01

    Human experimental pain studies are of value to study basic pain mechanisms under controlled conditions. The aim of this study was to investigate whether genetic variation across selected mu-, kappa- and delta-opioid receptor genes (OPRM1, OPRK1and OPRD1, respectively) influenced analgesic response to oxycodone in healthy volunteers. Experimental multimodal, multitissue pain data from previously published studies carried out in Caucasian volunteers were used. Data on thermal skin pain tolerance threshold (PTT) (n = 37), muscle pressure PTT (n = 31), mechanical visceral PTT (n = 43) and thermal visceral PTT (n = 41) were included. Genetic associations with pain outcomes were explored. Nineteen opioid receptor genetic polymorphisms were included in this study. Variability in oxycodone response to skin heat was associated with OPRM1 single-nucleotide polymorphisms (SNPs) rs589046 (P < 0.0001) and rs563649 (P < 0.0001). Variability in oxycodone response to visceral pressure was associated with four OPRM1 SNPs: rs589046 (P = 0.015), rs1799971 (P = 0.045), rs9479757 (P = 0.009) and rs533586 (P = 0.046). OPRM1 SNPs were not associated with oxycodone visceral heat threshold, however, one OPRD1 rs419335 reached significance (P = 0.015). Another OPRD1 SNP rs2234918 (P = 0.041) was associated with muscle pressure. There were no associations with OPRK1 SNPs and oxycodone response for any of the pain modalities. Associations were found between analgesic effects of oxycodone and OPRM1 and OPRD1 SNPs; therefore, variation in opioid receptor genes may partly explain responder characteristics to oxycodone.

  6. Lack of effect of chronic dextromethorphan on experimental pain tolerance in methadone-maintained patients

    PubMed Central

    Compton, Peggy A.; Ling, Walter; Torrington, Matt A.

    2014-01-01

    Good evidence exists to suggest that individuals on opioid maintenance for the treatment of addiction (i.e. methadone) are less tolerant of experimental pain than are matched controls or ex-opioid addicts, a phenomenon theorized to reflect opioid-induced hyperalgesia (OIH). Agonist activity at the excitatory ionotropic N-methyl-D-aspartate (NMDA) receptor on dorsal horn neurons has been implicated in the development of both OIH and its putative expression at the clinical level—opioid tolerance. The aim of this study was to evaluate the potential utility of the NMDA-receptor antagonist, dextromethorphan (DEX), to reverse or treat OIH in methadone-maintenance (MM) patients. Utilizing a clinical trial design and double-blind conditions, changes in pain threshold and tolerance [cold pressor (CP) and electrical stimulation (ES)] following a 5-week trial of DEX (titrated to 480 mg/day) in comparison with placebo was evaluated in a well-characterized sample of MM patients. The sample (n = 40) was 53% male and ethnically diverse (53% Latino, 28% African American, 10% White, 9% other), with a mean age of 48.0 years (SD = 6.97). Based on t-test analyses, no difference was found between groups on CP pain threshold, CP pain tolerance, ES pain threshold or ES pain tolerance, both pre- and postmedication. Notably, DEX-related changes significantly differed by gender, with women tending to show diminished tolerance for pain with DEX therapy. These results support that chronic high-dose NMDA antagonism does not improve tolerance for pain in MM patients, although a gender effect on DEX response is suggested. PMID:18507735

  7. Pain Sensitivity and Opioid Analgesia: A Pharmacogenomic Twin Study

    PubMed Central

    Angst, Martin S.; Phillips, Nicholas G.; Drover, David R.; Tingle, Martha; Ray, Amrita; Swan, Gary E.; Lazzeroni, Laura C.; Clark, J. David

    2012-01-01

    Opioids are the cornerstone medication for the management of moderate to severe pain. Unfortunately, vast inter-individual differences in dose requirements complicate their effective and safe clinical use. Mechanisms underlying such differences are incompletely understood, are likely multifactorial, and include genetic and environmental contributions. While accumulating evidence suggests that variants of several genes account for some of the observed response variance, the relative contribution of these factors remains unknown. This study used a twin paradigm to provide a global estimate of the genetic and environmental contributions to inter-individual differences in pain sensitivity and analgesic opioid effects. Eighty one monozygotic and 31 dizygotic twin pairs successfully underwent a computer-controlled infusion with the muopioid agonist alfentanil in a single occasion, randomized, double-blind and placebo-controlled study design. Pain sensitivity and analgesic effects were assessed with experimental heat and cold pressor pain models along with important covariates including demographic factors, depression, anxiety, and sleep quality. Significant heritability was detected for cold pressor pain tolerance and opioid-mediated elevations in heat and cold pressor pain thresholds. Genetic effects accounted for 12–60% of the observed response variance. Significant familial effects accounting for 24–32% of observed variance were detected for heat and cold pressor pain thresholds and opioid-mediated elevation in cold pressor pain tolerance. Significant covariates included age, gender, race, education, and anxiety. Results provide a strong rationale for more detailed molecular genetic studies to elucidate mechanisms underlying inter-individual differences in pain sensitivity and analgesic opioid responses. Such studies will require careful consideration of the studied pain phenotype. PMID:22444188

  8. Assessment of knee joint pain in experimental rodent models of osteoarthritis.

    PubMed

    Piel, Margaret J; Kroin, Jeffrey S; Im, Hee-Jeong

    2015-01-01

    Pain assessment in animal models of osteoarthritis is integral to interpretation of a model's utility in representing the clinical condition, and enabling accurate translational medicine. Here we describe two methods for behavioral pain assessments available for use in animal models of experimental osteoarthritic pain: Von Frey filaments and spontaneous activity monitoring.

  9. Diagnosis of neglected tropical diseases among patients with persistent digestive disorders (diarrhoea and/or abdominal pain ≥14 days): Pierrea multi-country, prospective, non-experimental case-control study.

    PubMed

    Polman, Katja; Becker, Sören L; Alirol, Emilie; Bhatta, Nisha K; Bhattarai, Narayan R; Bottieau, Emmanuel; Bratschi, Martin W; Burza, Sakib; Coulibaly, Jean T; Doumbia, Mama N; Horié, Ninon S; Jacobs, Jan; Khanal, Basudha; Landouré, Aly; Mahendradhata, Yodi; Meheus, Filip; Mertens, Pascal; Meyanti, Fransiska; Murhandarwati, Elsa H; N'Goran, Eliézer K; Peeling, Rosanna W; Ravinetto, Raffaella; Rijal, Suman; Sacko, Moussa; Saye, Rénion; Schneeberger, Pierre H H; Schurmans, Céline; Silué, Kigbafori D; Thobari, Jarir A; Traoré, Mamadou S; van Lieshout, Lisette; van Loen, Harry; Verdonck, Kristien; von Müller, Lutz; Yansouni, Cédric P; Yao, Joel A; Yao, Patrick K; Yap, Peiling; Boelaert, Marleen; Chappuis, François; Utzinger, Jürg

    2015-08-18

    Diarrhoea still accounts for considerable mortality and morbidity worldwide. The highest burden is concentrated in tropical areas where populations lack access to clean water, adequate sanitation and hygiene. In contrast to acute diarrhoea (<14 days), the spectrum of pathogens that may give rise to persistent diarrhoea (≥14 days) and persistent abdominal pain is poorly understood. It is conceivable that pathogens causing neglected tropical diseases play a major role, but few studies investigated this issue. Clinical management and diagnostic work-up of persistent digestive disorders in the tropics therefore remain inadequate. Hence, important aspects regarding the pathogenesis, epidemiology, clinical symptomatology and treatment options for patients presenting with persistent diarrhoea and persistent abdominal pain should be investigated in multi-centric clinical studies. This multi-country, prospective, non-experimental case-control study will assess persistent diarrhoea (≥14 days; in individuals aged ≥1 year) and persistent abdominal pain (≥14 days; in children/adolescents aged 1-18 years) in up to 2000 symptomatic patients and 2000 matched controls. Subjects from Côte d'Ivoire, Indonesia, Mali and Nepal will be clinically examined and interviewed using a detailed case report form. Additionally, each participant will provide a stool sample that will be examined using a suite of diagnostic methods (i.e., microscopic techniques, rapid diagnostic tests, stool culture and polymerase chain reaction) for the presence of bacterial and parasitic pathogens. Treatment will be offered to all infected participants and the clinical treatment response will be recorded. Data obtained will be utilised to develop patient-centred clinical algorithms that will be validated in primary health care centres in the four study countries in subsequent studies. Our research will deepen the understanding of the importance of persistent diarrhoea and related digestive disorders in

  10. Magnetohydrodynamic generator experimental studies

    NASA Technical Reports Server (NTRS)

    Pierson, E. S.

    1972-01-01

    The results for an experimental study of a one wavelength MHD induction generator operating on a liquid flow are presented. First the design philosophy and the experimental generator design are summarized, including a description of the flow loop and instrumentation. Next a Fourier series method of treating the fact that the magnetic flux density produced by the stator is not a pure traveling sinusoid is described and some results summarized. This approach appears to be of interest after revisions are made, but the initial results are not accurate. Finally, some of the experimental data is summarized for various methods of excitation.

  11. Introduction: chronic pain studies of the lidocaine patch 5% using the Neuropathic Pain Scale.

    PubMed

    Jensen, Mark P

    2004-01-01

    The manifestation of pain in any individual patient may result from a variety of underlying mechanisms that also may vary from one disease state to another. Global measures of pain intensity and relief are inadequate for characterizing specific pain qualities or identifying the unique effects of pain treatments on different pain qualities. The Neuropathic Pain Scale (NPS) is a recently developed measure designed to assess distinct pain qualities and may allow differentiation of therapeutic effects, even in cases where global pain response may be similar. Three studies are presented that provide preliminary evidence for the utility of the NPS for characterizing distinct pain qualities and changes in pain qualities in patients treated with the lidocaine patch 5% for a variety of neuropathic and non-neuropathic chronic pain conditions, including low-back pain, osteoarthritis, post-herpetic neuralgia, and painful diabetic neuropathy.

  12. Coping With Pain: Studies in Stress Inoculation.

    ERIC Educational Resources Information Center

    Horan, John J.; And Others

    The stress-inoculation paradigm for helping clients deal with pain consists of education about the psychological dimensions of pain, training in a number of coping skills relevant to each dimension, and practice in applying these skills to the noxious stimulus. Presented are two studies, the first of which represents a component analysis of stress…

  13. Coping With Pain: Studies in Stress Inoculation.

    ERIC Educational Resources Information Center

    Horan, John J.; And Others

    The stress-inoculation paradigm for helping clients deal with pain consists of education about the psychological dimensions of pain, training in a number of coping skills relevant to each dimension, and practice in applying these skills to the noxious stimulus. Presented are two studies, the first of which represents a component analysis of stress…

  14. The impact of neurodynamic testing on the perception of experimentally induced muscle pain.

    PubMed

    Coppieters, Michel W; Kurz, Kimberly; Mortensen, Thor Einar; Richards, Nicola L; Skaret, Ingrid A; McLaughlin, Laurie M; Hodges, Paul W

    2005-02-01

    Neurodynamic tests such as the straight leg raising (SLR) and slump test are frequently used for assessment of mechanosensitivity of neural tissues. However, there is ongoing debate in the literature regarding the contributions of neural and non-neural tissues to the elicited symptoms because many structures are affected by these tests. Sensitizing manoeuvres are limb or spinal movements added to neurodynamic tests, which aim to identify the origin of the symptoms by preferentially loading or unloading neural structures. A prerequisite for the use of sensitizing manoeuvres to identify neural involvement is that the addition of sensitizing manoeuvres has no impact on pain perception when the origin of the pain is non-neural. In this study, experimental muscle pain was induced by injection of hypertonic saline in tibialis anterior or soleus in 25 asymptomatic, naive volunteers. A first experiment investigated the impact of hip adduction, abduction, medial and lateral rotation in the SLR position. In a second experiment, the different stages of the slump test were examined. The intensity and area of experimentally induced muscle pain did not increase when sensitizing manoeuvres were added to the SLR or throughout the successive stages of the slump test. The findings of this study lend support to the validity of the use of sensitizing manoeuvres during neurodynamic testing.

  15. Mechanistic experimental pain assessment in computer users with and without chronic musculoskeletal pain.

    PubMed

    Ge, Hong-You; Vangsgaard, Steffen; Omland, Øyvind; Madeleine, Pascal; Arendt-Nielsen, Lars

    2014-12-06

    Musculoskeletal pain from the upper extremity and shoulder region is commonly reported by computer users. However, the functional status of central pain mechanisms, i.e., central sensitization and conditioned pain modulation (CPM), has not been investigated in this population. The aim was to evaluate sensitization and CPM in computer users with and without chronic musculoskeletal pain. Pressure pain threshold (PPT) mapping in the neck-shoulder (15 points) and the elbow (12 points) was assessed together with PPT measurement at mid-point in the tibialis anterior (TA) muscle among 47 computer users with chronic pain in the upper extremity and/or neck-shoulder pain (pain group) and 17 pain-free computer users (control group). Induced pain intensities and profiles over time were recorded using a 0-10 cm electronic visual analogue scale (VAS) in response to different levels of pressure stimuli on the forearm with a new technique of dynamic pressure algometry. The efficiency of CPM was assessed using cuff-induced pain as conditioning pain stimulus and PPT at TA as test stimulus. The demographics, job seniority and number of working hours/week using a computer were similar between groups. The PPTs measured at all 15 points in the neck-shoulder region were not significantly different between groups. There were no significant differences between groups neither in PPTs nor pain intensity induced by dynamic pressure algometry. No significant difference in PPT was observed in TA between groups. During CPM, a significant increase in PPT at TA was observed in both groups (P < 0.05) without significant differences between groups. For the chronic pain group, higher clinical pain intensity, lower PPT values from the neck-shoulder and higher pain intensity evoked by the roller were all correlated with less efficient descending pain modulation (P < 0.05). This suggests that the excitability of the central pain system is normal in a large group of computer users with low pain intensity

  16. Women with dysmenorrhea are hypersensitive to experimental deep muscle pain across the menstrual cycle.

    PubMed

    Iacovides, Stella; Baker, Fiona C; Avidon, Ingrid; Bentley, Alison

    2013-10-01

    Primary dysmenorrhea is a common painful condition in women that recurs every month across the reproductive years. The recurrent nociceptive input into the central nervous system that occurs during menstruation each month in women with dysmenorrhea is hypothesized to lead to increased sensitivity to painful stimuli. We investigated whether women with primary dysmenorrhea are hyperalgesic to deep muscle pain induced by a cleanly nociceptive method of hypertonic saline injection. Pain stimulation was applied both within an area of referred menstrual pain (lower back) and at a remote site outside of referred menstrual pain (forearm) in 12 healthy women with severe dysmenorrhea and 9 healthy women without dysmenorrhea, at 3 phases of the menstrual cycle: menstruation and follicular and luteal phases. Women rated their pain severity on a 100-mm visual analog scale every 30 seconds after injection until the pain subsided. In both groups of women, menstrual cycle phase had no effect on the reported intensity and duration of muscle pain. However, women with dysmenorrhea had increased sensitivity to experimental muscle pain both at the site of referred pain and at a remote nonpainful site, as assessed by peak pain severity visual analog scale rating, area under the visual analog scale curve, and pain duration, compared to women without dysmenorrhea. These data show that women with severe primary dysmenorrhea, who experience monthly menstrual pain, are hyperalgesic to deep muscle pain compared to women without dysmenorrhea. Our findings that dysmenorrheic women are hyperalgesic to a clinically relevant, deep muscle pain in areas within and outside of referred menstrual pain indicates lasting changes in pain sensitivity outside of the painful period during menstruation. Copyright © 2013 American Pain Society. Published by Elsevier Inc. All rights reserved.

  17. Caffeine does not attenuate experimentally induced ischemic pain in healthy subjects.

    PubMed

    Dellermalm, J; Segerdahl, M; Grass, S

    2009-11-01

    Caffeine is likely the most widely used psychoactive substance in the world. It is also an analgesic adjuvant and has individual analgesic properties. The latter effect has been attributed to adenosine receptor antagonism, but the site of action is unknown. The aim of this study was to investigate the analgesic properties of caffeine on experimentally induced ischemic pain and to attempt to elucidate whether the site of action is central or peripheral. Seventeen healthy subjects received intravenous (i.v.) regional and systemic infusions of caffeine at 10 mg/kg or placebo in a double-blind, crossover fashion to investigate the site of action for caffeine-induced analgesia. Subjects underwent a sub-maximum effort tourniquet test. Pain scores [visual analogue scale (VAS), 0-100] were assessed every minute up to a maximum of 45 min. The sum of pain scores (SPS, accumulation of VAS scores) was attenuated neither by systemic 2405 (+/-234) nor by i.v. regional caffeine 2427 (+/-190) as compared with placebo 2442 (+/-205), P=0.99 (mean+/-SEM). Time to maximal VAS score did not differ significantly between treatments, P=0.94. There was no correlation between caffeine concentration in plasma and time to maximal pain score, or between SPS and plasma concentration. Caffeine does not have an analgesic effect on ischemic pain, either by a peripheral or by a central site of action.

  18. Experimental muscle pain changes the spatial distribution of upper trapezius muscle activity during sustained contraction.

    PubMed

    Madeleine, Pascal; Leclerc, Fredéric; Arendt-Nielsen, Lars; Ravier, Philippe; Farina, Dario

    2006-11-01

    To investigate the effect of local excitation of nociceptive muscle afferents on the spatial distribution of muscle activity. Surface electromyographic (EMG) signals were recorded from the upper trapezius muscle of 10 healthy volunteers with a 5 x 13 electrode grid during 90-s isometric contractions before, during, 15 and 30 min after intramuscular injection of hypertonic (painful) or isotonic (non-painful) saline. From the multi-channel EMG recordings, two-dimensional maps of root mean square and mean power frequency were obtained. The centre of gravity of the root mean square map was used to quantify global changes in the spatial distribution of muscle activity. During sustained contractions, average root mean square increased, average mean frequency decreased and the centre of gravity moved cranially. During experimental muscle pain, compared to before injection, the average root mean square decreased and there was a caudal shift of the centre of gravity. Fifteen minutes after the painful injection the centre of gravity returned to its original position. Short-term dynamic reorganization of the spatial distribution of muscle activity occurred in response to nociceptive afferent input. The study furnishes an extension of the pain adaptation model indicating heterogeneous inhibition of muscle activity.

  19. Evaluation of pain in rats through facial expression following experimental tooth movement.

    PubMed

    Liao, Lina; Long, Hu; Zhang, Li; Chen, Helin; Zhou, Yang; Ye, Niansong; Lai, Wenli

    2014-04-01

    This study was carried out to evaluate pain in rats by monitoring their facial expressions following experimental tooth movement. Male Sprague-Dawley rats were divided into the following five groups based on the magnitude of orthodontic force applied and administration of analgesics: control; 20 g; 40 g; 80 g; and morphine + 40 g. Closed-coil springs were used to mimic orthodontic forces. The facial expressions of each rat were videotaped, and the resulting rat grimace scale (RGS) coding was employed for pain quantification. The RGS score increased on day 1 but showed no significant change thereafter in the control and 20-g groups. In the 40- and 80-g groups, the RGS scores increased on day 1, peaked on day 3, and started to decrease on day 5. At 14 d, the RGS scores were similar in control and 20-, 40-, and 80-g groups and did not return to baseline. The RGS scores in the morphine + 40-g group were significantly lower than those in the control group. Our results reveal that coding of facial expression is a valid method for evaluation of pain in rats following experimental tooth movement. Inactivated springs (no force) still cause discomfort and result in an increase in the RGS. The threshold force magnitude required to evoke orthodontic pain in rats is between 20 and 40 g. © 2014 Eur J Oral Sci.

  20. The effect of spinal manipulation on deep experimental muscle pain in healthy volunteers.

    PubMed

    O'Neill, Søren; Ødegaard-Olsen, Øystein; Søvde, Beate

    2015-01-01

    High-velocity low-amplitude (HVLA) spinal manipulation is commonly used in the treatment of spinal pain syndromes. The mechanisms by which HVLA-manipulation might reduce spinal pain are not well understood, but often assumed to relate to the reduction of biomechanical dysfunction. It is also possible however, that HVLA-manipulation involves a segmental or generalized inhibitory effect on nociception, irrespective of biomechanical function. In the current study it was investigated whether a local analgesic effect of HVLA-manipulation on deep muscle pain could be detected, in healthy individuals. Local, para-spinal muscle pain was induced by injection of 0.5 ml sterile, hyper-tonic saline on two separate occasions 1 week apart. Immediately following the injection, treatment was administered as either a) HVLA-manipulation or b) placebo treatment, in a randomized cross-over design. Both interventions were conducted by an experienced chiropractor with minimum 6 years of clinical experience. Participants and the researcher collecting data were blinded to the treatment allocation. Pain scores following saline injection were measured by computerized visual analogue pain scale (VAS) (0-100 VAS, 1 Hz) and summarized as a) Pain duration, b) Maximum VAS, c) Time to maximum VAS and d) Summarized VAS (area under the curve). Data analysis was performed as two-way analysis of variance with treatment allocation and session number as explanatory variables. Twenty-nine healthy adults (mean age 24.5 years) participated, 13 women and 16 men. Complete data was available for 28 participants. Analysis of variance revealed no statistically significant difference between active and placebo manipulation on any of the four pain measures. The current findings do not support the theory that HVLA-manipulation has a non-specific, reflex-mediated local or generalized analgesic effect on experimentally induced deep muscle pain. This in turn suggests, that any clinical analgesic effect of HVLA

  1. Imaging study of the painful heel syndrome

    SciTech Connect

    Williams, P.L.; Smibert, J.G.; Cox, R.; Mitchell, R.; Klenerman, L.

    1987-06-01

    A total of 45 patients with the painful heel syndrome without evidence of an associated inflammatory arthritis, seven of whom had pain in both heels, were studied using technetium-99 isotope bone scans and lateral and 45 degrees medial oblique radiographs of both feet. Of the 52 painful heels 31 (59.6%) showed increased uptake of tracer at the calcaneum. Patients with scans showing increased uptake tended to have more severe heel pain and responded more frequently to a local hydrocortisone injection. On plain x-ray, 39 of 52 painful heels (75%) and 24 of the 38 opposite nonpainful heels (63%) showed plantar spurs, compared with five of 63 (7.9%) heels in 59 age- and sex-matched controls. No evidence of stress fractures was seen.

  2. Parenting in the context of chronic pain: A controlled study of parents with chronic pain

    PubMed Central

    Wilson, Anna C.; Fales, Jessica L.

    2014-01-01

    Objectives This study aims to describe what adults with chronic pain experience in their role as parents, utilizing quantitative and qualitative methods. The first aim is to compare parents with chronic pain to parents without chronic pain on perceptions of their adolescent’s pain, parental response to pain, and catastrophizing beliefs about pain. The study also examined predictors of parental protective behaviors, and examined whether these associations differed by study group. Methods Parents with chronic pain (n=58) and parents without chronic pain (n=72) participated, and completed questionnaire measures of pain characteristics and pain interference, as well as measures of parental catastrophizing and protective pain responses. Parents with chronic pain also completed a structured interview about their experience of being a parent. Interview responses were videotaped and subsequently coded for content. Results Compared to controls, parents with chronic pain endorsed more pain in their adolescents, and were more likely to catastrophize about their adolescent’s pain and respond with protective behaviors. Parent’s own pain interference and the perception of higher pain in their adolescent was associated with increased protective parenting in the chronic pain group. Qualitative coding revealed a number of areas of common impact of chronic pain on parenting. Discussion Chronic pain impacts everyday parenting activities and emotions, and impacts pain-specific parent responses that are known to be related to increased pain and pain catastrophizing in children and adolescents. Parents with chronic pain might benefit from interventions that address potential parenting difficulties, and might improve outcomes for their children. PMID:25232862

  3. Modulation of pain-induced neuromuscular trunk responses by pain expectations: a single group study.

    PubMed

    Tétreau, Charles; Dubois, Jean-Daniel; Piché, Mathieu; Descarreaux, Martin

    2012-10-01

    The purpose of this study was to investigate the alteration of pain-induced neuromuscular trunk responses by expectations in healthy volunteers. Twenty-three asymptomatic participants performed series of flexion-extension movements in 3 different experimental conditions: innocuous heat stimulation (control) and noxious heat stimulation associated with expectations of low or high pain intensity. These stimuli were administered by a contact thermode placed over the lumbar region (L4 and L5) to assess the modulation of neuromuscular responses and kinematics during the flexion-extension task. Surface electromyography (EMG) of lumbar erector spinae at L2 and L3 and L4 and L5 as well as lumbopelvic kinematic variables were compared across conditions. Noxious stimulation significantly altered EMG responses but only in full trunk flexion. Interestingly, this alteration was significant only for muscles where noxious stimulation was applied (L4 and L5) and not for the other segment (L2 and L3). Conversely, expectations significantly altered EMG activity at L2 and L3 but not at the segment where noxious stimulation was applied. These results confirm previous findings and indicate that experimental pain can alter neuromuscular responses during a trunk flexion-extension task. Furthermore, this study suggests that expectations can alter some of these alterations. Future studies should determine whether neuromuscular changes induced by expectations may contribute to the transition from acute to chronic low-back pain. Copyright © 2012 National University of Health Sciences. Published by Mosby, Inc. All rights reserved.

  4. Pain fear avoidance and pain acceptance: a cross-sectional study comparing their influence on adjustment to chronic pain across three samples of patients.

    PubMed

    Esteve, Rosa; Ramírez-Maestre, Carmen

    2013-10-01

    Prior studies found that pain fear avoidance and pain acceptance are significantly associated with adjustment to chronic pain. The purpose of this study is to compare the influence of pain fear avoidance and pain acceptance on adjustment to chronic pain across three samples: patients with chronic back pain treated at primary care centres, patients with heterogeneous pain conditions treated at a pain clinic and patients with pain associated with inflammatory bowel disease. Structural equation modelling was used to test for differences between groups in the linear relationships between variables. The model had the best fit for the group of patients with back pain. Three significant relationships were equal across the groups: experiential avoidance on pain fear avoidance, pain intensity on pain fear avoidance, and pain fear avoidance on negative mood. The associations between both pain fear avoidance and pain acceptance and adjustment to chronic pain vary depending on the pain condition and the type of health care centres where the patients are treated.

  5. Relationships among Eysenck's extraversion, Rorschach's Erlebnistypus, and tolerance of experimental tonic pain (Cold Water Pressor Test).

    PubMed

    Ferracuti, Stefano; De Carolis, Antonella

    2005-02-01

    In a group of 42 healthy volunteers the correlations between the concept of Extraversion-Introversion as defined by Eysenck and Erlebnistypus as defined by Rorschach were analysed to relate these with the tolerance of an experimentally induced tonic pain. We conducted an experimental procedure comprising a test and retest. At test the subjects were administered the Rorschach, the Eysenck Personality Inventory, the Cold Water Pressor Test, a nongraduated Visual Analogue Scale, and the Italian version of the McGill Pain Questionnaire. At retest the experimental induction of pain was measured again. At test subjects who scored higher on the EPI Extraversion scale tolerated pain longer and did not modify their performance at retest. Also, the concepts of Extroversion defined by the Rorschach test and by the Extraversion scale of the Eysenck Personality Inventory shared some psychophysiological features of higher tolerance to pain. These personality features did not influence how subjects qualitatively describe the immediate painful experience.

  6. Effects of experimental tooth clenching on pain and intramuscular release of 5-HT and glutamate in patients with myofascial TMD.

    PubMed

    Dawson, Andreas; Ghafouri, Bijar; Gerdle, Björn; List, Thomas; Svensson, Peter; Ernberg, Malin

    2015-08-01

    It has been suggested that tooth clenching may be associated with local metabolic changes, and is a risk factor for myofascial temporomandibular disorders (M-TMD). This study investigated the effects of experimental tooth clenching on the levels of 5-HT, glutamate, pyruvate, and lactate, as well as on blood flow and pain intensity, in the masseter muscles of M-TMD patients. Fifteen patients with M-TMD and 15 pain-free controls participated. Intramuscular microdialysis was performed to collect 5-HT, glutamate, pyruvate, and lactate and to assess blood flow. Two hours after the insertion of a microdialysis catheter, participants performed a 20-minute repetitive tooth clenching task (50% of maximal voluntary contraction). Pain intensity was measured throughout. A significant effect of group (P<0.01), but not of time, was observed on 5-HT levels and blood flow. No significant effects of time or group occurred on glutamate, pyruvate, or lactate levels. Time and group had significant main effects on pain intensity (P<0.05 and <0.001). No significant correlations were identified between: (1) 5-HT, glutamate, and pain intensity; or between (2) pyruvate, lactate, and blood flow. This experimental tooth clenching model increased jaw muscle pain levels in M-TMD patients and evoked low levels of jaw muscle pain in controls. M-TMD patients had significantly higher levels of 5-HT than controls and significantly lower blood flow. These 2 factors may facilitate the release of other algesic substances that may cause pain.

  7. Chronic pain in Australia: a prevalence study.

    PubMed

    Blyth, F M; March, L M; Brnabic, A J; Jorm, L R; Williamson, M; Cousins, M J

    2001-01-01

    This study reports chronic pain prevalence in a randomly selected sample of the adult Australian population. Data were collected by Computer-Assisted Telephone Interview (CATI) using randomly generated telephone numbers and a two-stage stratified sample design. Chronic pain was defined as pain experienced every day for three months in the six months prior to interview. There were 17,543 completed interviews (response rate=70.8%). Chronic pain was reported by 17.1% of males and 20.0% of females. For males, prevalence peaked at 27.0% in the 65--69 year age group and for females, prevalence peaked at 31.0% in the oldest age group (80--84 years). Having chronic pain was significantly associated with older age, female gender, lower levels of completed education, and not having private health insurance; it was also strongly associated with receiving a disability benefit (adjusted OR=3.89, P<0.001) or unemployment benefit (adjusted OR=1.99, P<0.001); being unemployed for health reasons (adjusted OR=6.41, P<0.001); having poor self-rated health (adjusted OR=7.24, P<0.001); and high levels of psychological distress (adjusted OR=3.16, P<0.001). Eleven per cent of males and 13.5% of females in the survey reported some degree of interference with daily activities caused by their pain. Prevalence of interference was highest in the 55--59 year age group in both males (17.2%) and females (19.7%). Younger respondents with chronic pain were proportionately most likely to report interference due to pain, affecting 84.3% of females and 75.9% of males aged 20--24 years with chronic pain. Within the subgroup of respondents reporting chronic pain, the presence of interference with daily activities caused by pain was significantly associated with younger age; female gender; and not having private health insurance. There were strong associations between having interfering chronic pain and receiving disability benefits (adjusted OR=3.31, P<0.001) or being unemployed due to health reasons

  8. Comparison between the Analgesic Effect of two Techniques on the Level of Pain Perception During venipuncture in Children up to 7 Years of Age: A Quasi-Experimental Study

    PubMed Central

    Gupta, Vivek Vardhan; Kaur, Amanlo; Singla, Ruku; Chitkara, Neha; Bajaj, Krushnan V.; Rawat, H.C.L

    2014-01-01

    Background: Distraction techniques are often provided by nurses, parents or child life specialists and help in pain alleviation during procedures. The use of non pharmacological procedures to cope with pain behaviour is less costly and most of these procedures can be administered by a nurse. Hence, the aim of the present study was to assess and compare the analgesic effect of holding the child by a family member versus holding the child by a family member along with an animation distraction intervention on the level of pain perception during venipuncture in children up to seven years of age. Materials and Methods: Purposive sampling technique was used to select 70 children admitted in paediatric ward of Guru Gobind Singh Medical Hospital, Faridkot, 35 children in each group viz. Group 1(child held by family member during venipuncture) and Group 2 (child held by family member along with an animation distraction during venipuncture) and video clippings were made for each subject in both groups. Standardized FLACC pain scale was used to assess the level of pain during venipuncture by seeing the video clips of procedure in both groups. Results: Findings revealed that the mean pain score of Group 1 was 3.86 and that of Group 2 was 2.43. Findings revealed that in Group 1 majority 31(88.57%) got severe pain and none remained relaxed during venipuncture whereas in Group 2 majority 10(28.58%) got moderate pain, 09(25.71%) remained relaxed and only 07(20%) got severe pain. The comparison of mean pain score of both groups was checked statistically by computing independent t-test and the value of t comes out to be 7.199 with p-value 0.000*** which was found to be highly significant. Conclusion: The study concluded that when during painful procedures like venipuncture if children are given any non-pharmacological intervention like animated distraction along with their family member it helps in managing the pain. In other words, it distracts/diverts the child’s attention from

  9. Comparison between the Analgesic Effect of two Techniques on the Level of Pain Perception During venipuncture in Children up to 7 Years of Age: A Quasi-Experimental Study.

    PubMed

    Gupta, Harsh Vardhan; Gupta, Vivek Vardhan; Kaur, Amanlo; Singla, Ruku; Chitkara, Neha; Bajaj, Krushnan V; Rawat, H C L

    2014-08-01

    Distraction techniques are often provided by nurses, parents or child life specialists and help in pain alleviation during procedures. The use of non pharmacological procedures to cope with pain behaviour is less costly and most of these procedures can be administered by a nurse. Hence, the aim of the present study was to assess and compare the analgesic effect of holding the child by a family member versus holding the child by a family member along with an animation distraction intervention on the level of pain perception during venipuncture in children up to seven years of age. Purposive sampling technique was used to select 70 children admitted in paediatric ward of Guru Gobind Singh Medical Hospital, Faridkot, 35 children in each group viz. Group 1(child held by family member during venipuncture) and Group 2 (child held by family member along with an animation distraction during venipuncture) and video clippings were made for each subject in both groups. Standardized FLACC pain scale was used to assess the level of pain during venipuncture by seeing the video clips of procedure in both groups. Findings revealed that the mean pain score of Group 1 was 3.86 and that of Group 2 was 2.43. Findings revealed that in Group 1 majority 31(88.57%) got severe pain and none remained relaxed during venipuncture whereas in Group 2 majority 10(28.58%) got moderate pain, 09(25.71%) remained relaxed and only 07(20%) got severe pain. The comparison of mean pain score of both groups was checked statistically by computing independent t-test and the value of t comes out to be 7.199 with p-value 0.000*** which was found to be highly significant. The study concluded that when during painful procedures like venipuncture if children are given any non-pharmacological intervention like animated distraction along with their family member it helps in managing the pain. In other words, it distracts/diverts the child's attention from pain and results in better cooperation of child during

  10. Concept priming and pain: an experimental approach to understanding gender roles in sex-related pain differences.

    PubMed

    Fowler, Stephanie L; Rasinski, Heather M; Geers, Andrew L; Helfer, Suzanne G; France, Christopher R

    2011-04-01

    Prior research has found that sex differences in pain are partially due to individual variations in gender roles. In a laboratory study, we tested the hypothesis that the presence of covert gender role cues can also moderate the extent to which women and men experience pain. Specifically, we varied gender role cues by asking male and female participants to write about instances in which they behaved in a stereotypically feminine, masculine, or neutral manner. Pain and cardiovascular reactivity to the cold pressor task were then assessed. Results revealed that, when primed with femininity, men reported less pain and anxiety from the cold pressor task than women. However, no differences existed between the sexes in the masculine or neutral prime conditions. The results indicate that covert gender cues can alter pain reports. Further, at least in some situations, feminine role cues may be more influential on pain reports than masculine role cues.

  11. Antihyperalgesic effect of pentoxifylline on experimental inflammatory pain

    PubMed Central

    Vale, Mariana L; Benevides, Verônica M; Sachs, Daniela; Brito, Gerly A C; da Rocha, Francisco A C; Poole, Stephen; Ferreira, Sérgio H; Cunha, Fernando Q; Ribeiro, Ronaldo A

    2004-01-01

    The antihyperalgesic effect of pentoxifylline was investigated in three experimental pain models. Pentoxifylline (0.5–1.6 mg kg−1) given 30 min before the stimulus significantly inhibited the writhing response induced by the intraperitoneal (i.p.) administration of either acetic acid (−90%) or zymosan (−83%), but not that of iloprost, in mice, as well as the zymosan-induced articular hyperalgesia in the zymosan arthritis in rats (−50%). Pentoxifylline also inhibited the mechanical hypernociception in rats induced by the intraplantar injection of either carrageenin (−81%), bradykinin (−56%) or tumor necrosis factor α (TNF-α; −46%), but not that induced by interleukin-1β (IL-1β) or prostaglandin E2 (PGE2). Pentoxifylline did not inhibit the nociceptive response in the hot plate test in mice. Further, the antinociceptive effect of pentoxifylline in the writhing test in mice and the zymosan-induced articular hyperalgesia were not reversed by the coadministration of the opioid receptor antagonist naloxone. Thus, pentoxifylline antinociceptive effect is probably not mediated at a central level. Pentoxifylline significantly reduced TNF-α (−43%) and IL-1β (−42%) concentrations in the joint exudates of rats stimulated by intra-articular injection of zymosan and the production of both cytokines (−66 and −86%, respectively) by mouse peritoneal macrophages stimulated in vivo with zymosan as well as the expression of TNF-α at the tissue level in carrageenin-injected rat paws. In conclusion, the antinociceptive activity of pentoxifylline is associated with the inhibition of the release of both TNF-α and IL-1β. PMID:15520047

  12. Antihyperalgesic effect of pentoxifylline on experimental inflammatory pain.

    PubMed

    Vale, Mariana L; Benevides, Verônica M; Sachs, Daniela; Brito, Gerly A C; da Rocha, Francisco A C; Poole, Stephen; Ferreira, Sérgio H; Cunha, Fernando Q; Ribeiro, Ronaldo A

    2004-12-01

    The antihyperalgesic effect of pentoxifylline was investigated in three experimental pain models. Pentoxifylline (0.5-1.6 mg kg(-1)) given 30 min before the stimulus significantly inhibited the writhing response induced by the intraperitoneal (i.p.) administration of either acetic acid (-90%) or zymosan (-83%), but not that of iloprost, in mice, as well as the zymosan-induced articular hyperalgesia in the zymosan arthritis in rats (-50%). Pentoxifylline also inhibited the mechanical hypernociception in rats induced by the intraplantar injection of either carrageenin (-81%), bradykinin (-56%) or tumor necrosis factor alpha (TNF-alpha; -46%), but not that induced by interleukin-1beta (IL-1beta) or prostaglandin E(2) (PGE(2)). Pentoxifylline did not inhibit the nociceptive response in the hot plate test in mice. Further, the antinociceptive effect of pentoxifylline in the writhing test in mice and the zymosan-induced articular hyperalgesia were not reversed by the coadministration of the opioid receptor antagonist naloxone. Thus, pentoxifylline antinociceptive effect is probably not mediated at a central level. Pentoxifylline significantly reduced TNF-alpha (-43%) and IL-1beta (-42%) concentrations in the joint exudates of rats stimulated by intra-articular injection of zymosan and the production of both cytokines (-66 and -86%, respectively) by mouse peritoneal macrophages stimulated in vivo with zymosan as well as the expression of TNF-alpha at the tissue level in carrageenin-injected rat paws. In conclusion, the antinociceptive activity of pentoxifylline is associated with the inhibition of the release of both TNF-alpha and IL-1beta.

  13. The Pain Management Life History Calendar: A Pilot Study.

    PubMed

    McDonald, Deborah Dillon; Barri, Caroline

    2015-08-01

    Pain management trajectory data that includes previous pain treatments, timing, changes, and outcomes provide crucial data for patients with chronic pain and their practitioners to use when discussing ways to optimize pain management regimens. The aim of this study was to test the use of the life history calendar method to identify pain treatments, treatment regimens, timing, and outcomes of the pain management trajectory of individuals with chronic pain, and to examine feasibility. A pilot, descriptive, methodological design was used. Settings included community-based sites such as congregate housing. Nineteen community-dwelling older adults with osteoarthritis (OA) pain of at least 1 year's duration participated. Participants were interviewed and asked to chronicle from the beginning of the OA pain to the present all of their pain treatments and treatment effects (pain outcomes and adverse events). Raters independently content analyzed the transcribed interviews to identify pain treatments, treatment groupings (regimens), and treatment effects on pain. Feasibility of patients reporting their pain management trajectories was content analyzed by identifying participant difficulty identifying pain treatments, treatment effects, treatment sequence; and difficulty discriminating between treatments, and between OA pain and other pain sources. Individual pain management trajectories were constructed that depicted chronological order of pain treatment regimens and treatment effects. Participants identified pain treatments, discriminate between treatments and between OA and other conditions, and identified treatment effects. Treatment sequence was identified, but more precise timing was generally not reported. Pain management trajectories could provide a helpful way for practitioners to discuss safe, efficacious pain management options with patients.

  14. Observer influences on pain: an experimental series examining same-sex and opposite-sex friends, strangers, and romantic partners.

    PubMed

    Edwards, Rhiannon; Eccleston, Christopher; Keogh, Edmund

    2017-05-01

    Despite the well-documented sex and gender differences, little is known about the relative impact of male-female social interactions on pain. Three experiments were conducted to investigate whether the type of interpersonal relationship men and women have with an observer affects how they respond to experimental pain. Study 1 recruited friends and strangers, study 2 examined the effects of same- and opposite-sex friends, whereas study 3 investigated the differences between opposite-sex friends and opposite-sex romantic partners. One hundred forty-four dyads were recruited (48 in each study). One person from each dyad completed 2 pain tasks, whereas the other person observed in silence. Overall, the presence of another person resulted in an increase in pain threshold and tolerance on the cold-pressor task and algometer. The sex status of the dyads also had a role, but only within the friendship groups. In particular, male friends had the most pronounced effect on men's pain, increasing pain tolerance. We suggest that the presence of an observer, their sex, and the nature of the participant-observer relationship all influence how pain is reported. Further research should focus on dyadic relationships, and their influence on how men and women report and communicate pain in specific contexts.

  15. Experimental pain processing in individuals with cognitive impairment: current state of the science.

    PubMed

    Defrin, Ruth; Amanzio, Martina; de Tommaso, Marina; Dimova, Violeta; Filipovic, Sasa; Finn, David P; Gimenez-Llort, Lydia; Invitto, Sara; Jensen-Dahm, Christina; Lautenbacher, Stefan; Oosterman, Joukje M; Petrini, Laura; Pick, Chaim G; Pickering, Gisele; Vase, Lene; Kunz, Miriam

    2015-08-01

    Cognitive impairment (CI) can develop during the course of ageing and is a feature of many neurological and neurodegenerative diseases. Many individuals with CI have substantial, sustained, and complex health care needs, which frequently include pain. However, individuals with CI can have difficulty communicating the features of their pain to others, which in turn presents a significant challenge for effective diagnosis and treatment of their pain. Herein, we review the literature on responsivity of individuals with CI to experimental pain stimuli. We discuss pain responding across a large number of neurological and neurodegenerative disorders in which CI is typically present. Overall, the existing data suggest that pain processing is altered in most individuals with CI compared with cognitively intact matched controls. The precise nature of these alterations varies with the type of CI (or associated clinical condition) and may also depend on the type of pain stimulation used and the type of pain responses assessed. Nevertheless, it is clear that regardless of the etiology of CI, patients do feel noxious stimuli, with more evidence for hypersensitivity than hyposensitivity to these stimuli compared with cognitively unimpaired individuals. Our current understanding of the neurobiological mechanisms underpinning these alterations is limited but may be enhanced through the use of animal models of CI, which also exhibit alterations in nociceptive responding. Further research using additional behavioural indices of pain is warranted. Increased understanding of altered experimental pain processing in CI will facilitate the development of improved diagnostic and therapeutic approaches for pain in individuals with CI.

  16. IL-17 is not essential for inflammation and chronic pelvic pain development in an experimental model of chronic prostatitis/chronic pelvic pain syndrome.

    PubMed

    Motrich, Ruben D; Breser, María L; Sánchez, Leonardo R; Godoy, Gloria J; Prinz, Immo; Rivero, Virginia E

    2016-03-01

    Pain and inflammation in the absence of infection are hallmarks in chronic prostatitis and chronic pelvic pain syndrome (CP/CPPS) patients. The etiology of CP/CPPS is unclear, and autoimmunity has been proposed as a cause. Experimental autoimmune prostatitis (EAP) models have long been used for studying CP/CPPS. Herein, we studied prostate inflammation induction and chronic pelvic pain development in EAP using IL-12p40-KO, IL-4-KO, IL-17-KO, and wild-type (C57BL/6) mice. Prostate antigen (PAg) immunization in C57BL/6 mice induced specific Th1 and Th17 immune responses and severe prostate inflammation and cell infiltration, mainly composed of CD4 T cells and macrophages. Moreover, chronic pelvic pain was evidenced by increased allodynia responses. In immunized IL-17-KO mice, the presence of a prominent PAg-specific Th1 immune response caused similar prostate inflammation and chronic pelvic pain. Furthermore, markedly high PAg-specific Th1 immune responses, exacerbated prostate inflammation, and chronic pelvic pain were detected in immunized IL-4-KO mice. Conversely, immunized IL-12p40-KO mice developed PAg-specific Th2 immune responses, characterized by high IL-4 secretion and neither infiltration nor damage in the prostate. As observed in wild-type control animals, IL12p40-KO mice did not evidence tactile allodynia responses. Our results suggest that, as in patients, chronic pelvic pain is a consequence of prostate inflammation. After PAg immunization, a Th1-associated immune response develops and induces prostate inflammation and chronic pelvic pain. The absence of Th1 or Th2 cytokines, respectively, diminishes or enhances EAP susceptibility. In addition, IL-17 showed not to be essential for pathology induction and chronic pelvic pain development.

  17. Comparison of pain scale preferences and pain intensity according to pain scales among Turkish Patients: a descriptive study.

    PubMed

    Yazici Sayin, Yazile; Akyolcu, Neriman

    2014-03-01

    Pain scale preferences may vary among patients. Providing a choice of which pain scale to use might be helpful for patients. The aim of this study was to determine patient pain scale preferences and compare the level of agreement among pain scales commonly used during postoperative pain assessment. A total of 621 patients during the early postoperative period were enrolled in this descriptive study. A questionnaire form, the faces pain scale (FPS), visual analog scale (VAS), numeric rating scale (NRS), verbal descriptor scale (VDS), thermometer pain scale (TPS), McGill Pain Questionnaire (MPQ), Short-form McGill Pain Questionnaire (SFMPQ), and Brief Pain Inventory (BPI) were used to collect data. Most patients reported that their pain was not measured with any of the pain scales. Patient preference for pain scales were as follows: 97.4% FPS, 88.6% NRS, 84.1% VDS, 78.1% TPS, 60.1% SFMPQ, 37.0% BPI, 11.4% VAS, and 10.5% MPQ. Education was an important factor in the preferences for all scales (p < .000). The level of pain determined by the VAS did not correlate with the level of pain identified by the NRS, TPS, FPS, and VDS (p < .05). There was no difference among the levels of pain for the NRS, TPS, FPS and VDS (p > .05), but there was for the VAS (p < .05). The pain scales chosen should be reliable, valid, and able to evaluate the effects of treatment. The results suggest that the NRS, TPS, FPS, and VDS were appropriate pain rating scales for the participants in this study, and that the VAS should be used in combination with one of these scales.

  18. Bilateral experimental muscle pain changes electromyographic activity of human jaw-closing muscles during mastication.

    PubMed

    Svensson, P; Houe, L; Arendt-Nielsen, L

    1997-08-01

    The effects of bilateral experimental muscle pain on human masticatory patterns were studied. Jaw movements and electromyographic (EMG) recordings of the jaw-closing muscles were divided into multiple single masticatory cycles and analyzed on a cycle-by-cycle basis. In ten men simultaneous bilateral injections of hypertonic saline (5%) into the masseter muscles caused strong pain (mean+/-SE: 7.5+/-0.4 on a 0-10 scale), significantly reduced EMG activity of jaw-closing muscles in the agonist phase, and significantly increased EMG activity in the antagonist phase. Nine of the subjects reported a sensation of less intense mastication during pain. Injections of isotonic saline (0.9%) did not cause pain or significant changes in masticatory patterns. The influence of higher brain centers on conscious human mastication can not be discarded but the observed phase-dependent modulation could be controlled by local neural circuits and/or a central pattern generator in the brain stem which are capable of integrating bilateral nociceptive afferent activity.

  19. Antero-posterior activity changes in the superficial masseter muscle after exposure to experimental pain.

    PubMed

    Türp, Jens C; Schindler, Hans J; Pritsch, Maria; Rong, Qiguo

    2002-04-01

    The aim of this randomized, controlled, double-blind study was to examine how the activation pattern of the masseter muscle changes during natural function when experimental pain is induced in a discrete anterior area of the muscle. In 20 subjects, three bipolar surface electrodes and three intramuscular fine-wire electrodes (antero-posterior mapping) were simultaneously attached above and in the right masseter muscle to record the electromyographic (EMG) activity during unilateral chewing before and after infusion of a 0.9% isotonic and 5% hypertonic saline bolus in the anterior area of the muscle. The activity of the contralateral masseter muscle was registered by surface electrodes. In addition, the development of pain intensity was quantitatively measured with a numerical rating scale (NRS). While both saline concentrations caused pain, the hypertonic solution evoked stronger pain. The experiments also provided evidence of a significant although differential activity reduction of the ipsilateral masseter muscle in the antero-posterior direction. The activity reduction decreased with increasing distance from the location of the infusion. The results support the idea that the strategy of differential activation protects the injured muscle while simultaneously maintaining optimal function.

  20. Sex differences in pain: a brief review of clinical and experimental findings

    PubMed Central

    Bartley, E. J.; Fillingim, R. B.

    2013-01-01

    Summary Recent years have witnessed substantially increased research regarding sex differences in pain. The expansive body of literature in this area clearly suggests that men and women differ in their responses to pain, with increased pain sensitivity and risk for clinical pain commonly being observed among women. Also, differences in responsivity to pharmacological and non-pharmacological pain interventions have been observed; however, these effects are not always consistent and appear dependent on treatment type and characteristics of both the pain and the provider. Although the specific aetiological basis underlying these sex differences is unknown, it seems inevitable that multiple biological and psychosocial processes are contributing factors. For instance, emerging evidence suggests that genotype and endogenous opioid functioning play a causal role in these disparities, and considerable literature implicates sex hormones as factors influencing pain sensitivity. However, the specific modulatory effect of sex hormones on pain among men and women requires further exploration. Psychosocial processes such as pain coping and early-life exposure to stress may also explain sex differences in pain, in addition to stereotypical gender roles that may contribute to differences in pain expression. Therefore, this review will provide a brief overview of the extant literature examining sex-related differences in clinical and experimental pain, and highlights several biopsychosocial mechanisms implicated in these male–female differences. The future directions of this field of research are discussed with an emphasis aimed towards further elucidation of mechanisms which may inform future efforts to develop sex-specific treatments. PMID:23794645

  1. Antihypernociceptive activity of anethole in experimental inflammatory pain.

    PubMed

    Ritter, Alessandra M V; Domiciano, Talita P; Verri, Waldiceu A; Zarpelon, Ana Carla; da Silva, Lorena G; Barbosa, Carmem P; Natali, Maria Raquel M; Cuman, Roberto K N; Bersani-Amado, Ciomar A

    2013-04-01

    Anethole has been reported to have antioxidant, antibacterial, antifungal, antiinflammatory, and anesthetic properties. In the present study, we evaluated the effects of anethole in two pain models of inflammatory origin: acute inflammation induced by carrageenan and persistent inflammation induced by Complete Freund's adjuvant. We evaluated the effects of anethole (125, 250, and 500 mg/kg) on the development of paw oedema and mechanical hypernociception. The liver was collected for histological analysis. Paw skin was collected to determine the levels of the cytokines tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-17 (IL-17), and myeloperoxidase activity. Blood was collected to assess alanine transaminase (ALT) and aspartate transaminase (AST). The chemical composition of star anise oil was determined by gas chromatography/mass spectrometry (GC/MS), showing a presence of anethole of 98.1%. Oral pretreatment with anethole in mice inhibited paw oedema, mechanical pernociception, myelopewroxidase activity, TNF-α, IL-1β and IL-17 levels in acute and persistent inflammation models. Additionally, anethole treatment did not alter prostaglandin E2-induced mechanical hypernociception. Possible side effects were also examined. Seven-day anethole treatment did not alter plasma AST and ALT levels, and the histological profile of liver tissue was normal. The present study provides evidence of the antiinflammatory and analgesic activities of anethole in acute and persistent inflammation models.

  2. Effect of endocannabinoid degradation on pain: role of FAAH polymorphisms in experimental and postoperative pain in women treated for breast cancer.

    PubMed

    Cajanus, Kristiina; Holmström, Emil J; Wessman, Maija; Anttila, Verneri; Kaunisto, Mari A; Kalso, Eija

    2016-02-01

    Fatty acid amide hydrolase (FAAH) metabolizes the endocannabinoid anandamide, which has an important role in nociception. We investigated the role of common FAAH single-nucleotide polymorphisms (SNPs) in experimentally induced and postoperative pain. One thousand women undergoing surgery for breast cancer participated in the study. They were tested for cold (n = 900) and heat pain (n = 1000) sensitivity. After surgery, their pain intensities and analgesic consumption were carefully registered. FAAH genotyping was performed using MassARRAY platform and genome-wide chip (n = 926). Association between 8 FAAH SNPs and 9 pain phenotypes was analyzed using linear regression models. The results showed that carrying 2 copies of a missense variant converting proline at position 129 to threonine (rs324420) resulted in significantly lower cold pain sensitivity and less need for postoperative analgesia. More specifically, rs324420 and another highly correlated SNP, rs1571138, associated significantly with cold pain intensity (corrected P value, 0.0014; recessive model). Patients homozygous for the minor allele (AA genotype) were less sensitive to cold pain (β = -1.48; 95% CI, -2.14 to -0.8). Two other SNPs (rs3766246 and rs4660928) showed nominal association with cold pain, and SNPs rs4141964, rs3766246, rs324420, and rs1571138 nominal association with oxycodone consumption. In conclusion, FAAH gene variation was shown to associate with cold pain sensitivity with P129T/rs324420 being the most likely causal variant as it is known to reduce the FAAH enzyme activity. The same variant showed nominal association with postoperative oxycodone consumption. Our conclusions are, however, limited by the lack of replication and the results should be replicated in an independent cohort.

  3. Inflammation-induced hyperalgesia: effects of timing, dosage, and negative affect on somatic pain sensitivity in human experimental endotoxemia.

    PubMed

    Wegner, Alexander; Elsenbruch, Sigrid; Maluck, Janina; Grigoleit, Jan-Sebastian; Engler, Harald; Jäger, Marcus; Spreitzer, Ingo; Schedlowski, Manfred; Benson, Sven

    2014-10-01

    Inflammation-induced pain amplification and hypersensitivity play a role in the pathophysiology of numerous clinical conditions. Experimental endotoxemia has recently been implemented as model to analyze immune-mediated processes in human pain. In this study, we aimed to analyze dose- and time-dependent effects of lipopolysaccharide (LPS) on clinically-relevant pain models for musculoskeletal and neuropathic pain as well as the interaction among LPS-induced changes in inflammatory markers, pain sensitivity and negative affect. In this randomized, double-blind, placebo-controlled study, healthy male subjects received an intravenous injection of either a moderate dose of LPS (0.8 ng/kg Escherichiacoli), low-dose LPS (0.4 ng/kg), or saline (placebo control group). Pressure pain thresholds (PPT), mechanical pain sensitivity (MPS), and cold pain sensitivity (CP) were assessed before and 1, 3, and 6h post injection to assess time-dependent LPS effects on pain sensitivity. Plasma cytokines (TNF-α, IL-6, IL-8, IL-10) and state anxiety were repeatedly measured before, and 1, 2, 3, 4, and 6h after injection of LPS or placebo. LPS administration induced a systemic immune activation, reflected by significant increases in cytokine levels, body temperature, and negative mood with pronounced effects to the higher LPS dose. Significant decreases of PPTs were observed only 3h after injection of the moderate dose of LPS (0.8 ng/kg). MPS and CP were not affected by LPS-induced immune activation. Correlation analyses revealed that decreased PPTs were associated with peak IL-6 increases and negative mood. Our results revealed widespread increases in musculoskeletal pain sensitivity in response to a moderate dose of LPS (0.8 ng/kg), which correlate both with changes in IL-6 and negative mood. These data extend and refine existing knowledge about immune mechanisms mediating hyperalgesia with implications for the pathophysiology of chronic pain and neuropsychiatric conditions. Copyright

  4. Center of Pressure Displacement of Standing Posture during Rapid Movements Is Reorganised Due to Experimental Lower Extremity Muscle Pain

    PubMed Central

    Shiozawa, Shinichiro; Hirata, Rogerio Pessoto; Graven-Nielsen, Thomas

    2015-01-01

    Background Postural control during rapid movements may be impaired due to musculoskeletal pain. The purpose of this study was to investigate the effect of experimental knee-related muscle pain on the center of pressure (CoP) displacement in a reaction time task condition. Methods Nine healthy males performed two reaction time tasks (dominant side shoulder flexion and bilateral heel lift) before, during, and after experimental pain induced in the dominant side vastus medialis or the tibialis anterior muscles by hypertonic saline injections. The CoP displacement was extracted from the ipsilateral and contralateral side by two force plates and the net CoP displacement was calculated. Results Compared with non-painful sessions, tibialis anterior muscle pain during the peak and peak-to-peak displacement for the CoP during anticipatory postural adjustments (APAs) of the shoulder task reduced the peak-to-peak displacement of the net CoP in the medial-lateral direction (P<0.05). Tibialis anterior and vastus medialis muscle pain during shoulder flexion task reduced the anterior-posterior peak-to-peak displacement in the ipsilateral side (P<0.05). Conclusions The central nervous system in healthy individuals was sufficiently robust in maintaining the APA characteristics during pain, although the displacement of net and ipsilateral CoP in the medial-lateral and anterior-posterior directions during unilateral fast shoulder movement was altered. PMID:26680777

  5. Analyzing musculoskeletal neck pain, measured as present pain and periods of pain, with three different regression models: a cohort study.

    PubMed

    Grimby-Ekman, Anna; Andersson, Eva M; Hagberg, Mats

    2009-06-19

    In the literature there are discussions on the choice of outcome and the need for more longitudinal studies of musculoskeletal disorders. The general aim of this longitudinal study was to analyze musculoskeletal neck pain, in a group of young adults. Specific aims were to determine whether psychosocial factors, computer use, high work/study demands, and lifestyle are long-term or short-term factors for musculoskeletal neck pain, and whether these factors are important for developing or ongoing musculoskeletal neck pain. Three regression models were used to analyze the different outcomes. Pain at present was analyzed with a marginal logistic model, for number of years with pain a Poisson regression model was used and for developing and ongoing pain a logistic model was used. Presented results are odds ratios and proportion ratios (logistic models) and rate ratios (Poisson model). The material consisted of web-based questionnaires answered by 1204 Swedish university students from a prospective cohort recruited in 2002. Perceived stress was a risk factor for pain at present (PR = 1.6), for developing pain (PR = 1.7) and for number of years with pain (RR = 1.3). High work/study demands was associated with pain at present (PR = 1.6); and with number of years with pain when the demands negatively affect home life (RR = 1.3). Computer use pattern (number of times/week with a computer session > or = 4 h, without break) was a risk factor for developing pain (PR = 1.7), but also associated with pain at present (PR = 1.4) and number of years with pain (RR = 1.2). Among life style factors smoking (PR = 1.8) was found to be associated to pain at present. The difference between men and women in prevalence of musculoskeletal pain was confirmed in this study. It was smallest for the outcome ongoing pain (PR = 1.4) compared to pain at present (PR = 2.4) and developing pain (PR = 2.5). By using different regression models different aspects of neck pain pattern could be addressed and

  6. Spinal Disinhibition in Experimental and Clinical Painful Diabetic Neuropathy.

    PubMed

    Marshall, Andrew G; Lee-Kubli, Corinne; Azmi, Shazli; Zhang, Michael; Ferdousi, Maryam; Mixcoatl-Zecuatl, Teresa; Petropoulos, Ioannis N; Ponirakis, Georgios; Fineman, Mark S; Fadavi, Hassan; Frizzi, Katie; Tavakoli, Mitra; Jeziorska, Maria; Jolivalt, Corinne G; Boulton, Andrew J M; Efron, Nathan; Calcutt, Nigel A; Malik, Rayaz A

    2017-02-15

    Impaired rate dependent depression (RDD) of the Hoffman-reflex is associated with reduced dorsal spinal cord potassium chloride co-transporter expression and impaired spinal GABAA receptor function, indicative of spinal inhibitory dysfunction. We have investigated the pathogenesis of impaired RDD in diabetic rodents exhibiting features of painful neuropathy and the translational potential of this marker of spinal inhibitory dysfunction in human painful diabetic neuropathy. Impaired RDD and allodynia were present in type 1 and type 2 diabetic rats but not in rats with type 1 diabetes receiving insulin supplementation that did not restore normoglycemia. Impaired RDD in diabetic rats was rapidly normalized by spinal delivery of duloxetine acting via 5HT2A receptors and temporally coincident with the alleviation of allodynia. Deficits in RDD and corneal nerve density were demonstrated in patients with painful diabetic neuropathy when compared to healthy control subjects and patients with painless diabetic neuropathy. Spinal inhibitory dysfunction and peripheral small fibre pathology may contribute to the clinical phenotype in painful diabetic neuropathy. Deficits in RDD may help to identify patients with spinally mediated painful diabetic neuropathy who may respond optimally to therapies such as duloxetine.

  7. Nursing pain management--a qualitative interview study of patients with pain, hospitalized for cancer treatment.

    PubMed

    Rustøen, Tone; Gaardsrud, Torill; Leegaard, Marit; Wahl, Astrid K

    2009-03-01

    Pain is a significant symptom in cancer patients. Understanding of patients' experiences in relation to pain management is important in evidence-based nursing in the field of pain. The aim of this study was to explore cancer patients' experiences of nursing pain management during hospitalization for cancer treatment. Eighteen cancer patients participated in the study, all with advanced cancer, including skeleton metastases. The female participants all had breast cancer, and the male participants all had prostate cancer. Data were collected by in-depth interviews, and qualitative description was used to entail low-inference interpretation to reach an understanding of the essence of pain and nursing pain management. Patients found it somewhat difficult to express their expectations of nursing pain management and competencies. However, 1) being present and supportive; 2) giving information and sharing knowledge; 3) taking care of medication; and 4) recognizing the pain emerged as themes in nursing pain management. Although patients believed that nurses were caring persons, they perceived differences between nurses in the ways they handled pain management. Furthermore, some patients experienced a lack of information from nurses in relation to pain management. Although cancer patients' experiences showed the importance of nurses in pain management, it seems that nurses should have a clearer role in cancer pain management in relation to counseling and patient education. The results from this study can increase nurses' awareness of their role in pain management as a first step in improving pain management for patients.

  8. An acceptance-based intervention for children and adolescents with cancer experiencing acute pain - a single-subject study.

    PubMed

    Thorsell Cederberg, Jenny; Dahl, JoAnne; von Essen, Louise; Ljungman, Gustaf

    2017-01-01

    Children and adolescents with cancer report pain as one of their most recurrent and troublesome symptoms throughout the cancer trajectory. Pain evokes psychological distress, which in turn has an amplifying effect on the pain experience. Acceptance-based interventions for experimentally induced acute pain predict increased pain tolerance, decreased pain intensity and decreased discomfort of pain. The aim of this study was to preliminarily evaluate an acceptance-based intervention for children and adolescents with cancer experiencing acute pain, with regard to feasibility and effect on pain intensity and discomfort of pain. This is a single-subject study with an AB design with a nonconcurrent multiple baseline. Children and adolescents aged four to 18 years undergoing cancer treatment at the Children's University Hospital, Uppsala, Sweden, reporting sustained acute pain were offered participation. Pain intensity and discomfort of pain were measured during baseline and at post-intervention. The intervention consisted of a pain exposure exercise lasting approximately 15 minutes. Five children participated in the study. All participants completed the intervention and reported that it had helped them to cope with the pain in the moment. All participants reported decreased discomfort of pain at post-measurement, three of whom also reported decreased pain intensity. The results suggest that an acceptance-based intervention may help children and adolescents with cancer to cope with the pain that is often associated with cancer treatment in spite of pharmacological pain management. The results are tentative but promising and warrant further investigation.

  9. Voluntary wheel running delays disease onset and reduces pain hypersensitivity in early experimental autoimmune encephalomyelitis (EAE).

    PubMed

    Benson, Curtis; Paylor, John W; Tenorio, Gustavo; Winship, Ian; Baker, Glen; Kerr, Bradley J

    2015-09-01

    Multiple sclerosis (MS) is classically defined by motor deficits, but it is also associated with the secondary symptoms of pain, depression, and anxiety. Up to this point modifying these secondary symptoms has been difficult. There is evidence that both MS and the animal model experimental autoimmune encephalomyelitis (EAE), commonly used to study the pathophysiology of the disease, can be modulated by exercise. To examine whether limited voluntary wheel running could modulate EAE disease progression and the co-morbid symptoms of pain, mice with EAE were allowed access to running wheels for 1h every day. Allowing only 1h every day of voluntary running led to a significant delay in the onset of clinical signs of the disease. The development of mechanical allodynia was assessed using Von Frey hairs and indicated that wheel running had a modest positive effect on the pain hypersensitivity associated with EAE. These behavioral changes were associated with reduced numbers of cFOS and phosphorylated NR1 positive cells in the dorsal horn of the spinal cord compared to no-run EAE controls. In addition, within the dorsal horn, voluntary wheel running reduced the number of infiltrating CD3(+) T-cells and reduced the overall levels of Iba1 immunoreactivity. Using high performance liquid chromatography (HPLC), we observed that wheel-running lead to significant changes in the spinal cord levels of the antioxidant glutathione. Oxidative stress has separately been shown to contribute to EAE disease progression and neuropathic pain. Together these results indicate that in mice with EAE, voluntary motor activity can delay the onset of clinical signs and reduce pain symptoms associated with the disease. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Postoperative Pain Following Foot and Ankle Surgery: A Prospective Study

    PubMed Central

    Chou, Loretta B.; Wagner, Dominic; Witten, Daniela M.; Martinez-Diaz, Gabriel J.; Brook, Nancy S.; Toussaint, Michele; Carroll, Ian R.

    2009-01-01

    Background Orthopaedic procedures have been reported to have the highest incidence of pain compared to other types of operations. There are limited studies in the literature that investigate postoperative pain. Materials and Methods A prospective study of 98 patients undergoing orthopedic foot and ankle operations was undertaken to evaluate their pain experience. A Short-Form McGill Pain Questionnaire (SF-MPQ) was administered preoperatively and postoperatively. Results The results showed that patients who experienced pain before the operation anticipated feeling higher pain intensity immediately postoperatively. Patients, on average, experienced higher pain intensity 3 days after the operation than anticipated. The postoperative pain intensity at 3 days was the most severe, while postoperative pain intensity at 6 weeks was the least severe. Age, gender and preoperative diagnosis (acute versus chronic) did not have a significant effect on the severity of pain that patients experienced. Six weeks following the operation, the majority of patients felt no pain. In addition, the severity of preoperative pain was highly predictive of their anticipated postoperative pain and 6-week postoperative pain, and both preoperative pain and anticipated pain predict higher immediate postoperative pain. Conclusion The intensity of patients' preoperative pain was predictive of the anticipated postoperative pain. Patients' preoperative pain and anticipated postoperative pain were independently predictive of the 3-day postoperative pain. The higher pain intensity a patient experienced preoperatively suggested that their postoperative pain severity would be greater. Therefore, surgeons should be aware of these findings when treating postoperative pain after orthopaedic foot and ankle operations. PMID:19026197

  11. Acupuncture-related modulation of pain-associated brain networks during electrical pain stimulation: a functional magnetic resonance imaging study.

    PubMed

    Theysohn, Nina; Choi, Kyung-Eun; Gizewski, Elke R; Wen, Ming; Rampp, Thomas; Gasser, Thomas; Dobos, Gustav J; Forsting, Michael; Musial, Frauke

    2014-12-01

    Findings of existing functional MRI (fMRI) studies on the neural mechanisms that mediate effects of acupuncture analgesia are inconsistent. This study analyzes the effects of manual acupuncture on pain ratings and brain activation in response to experimental, electrical pain stimuli. Fourteen healthy volunteers were examined by using a 1.5-T MRI scanner. The intensity of pain stimuli was adjusted to individual pain ratings on a numeric rating scale. Baseline fMRI was performed during electrical pain stimulation in a blocked design. For the second session, manual acupuncture with repeated stimulation was performed on contralateral acupoints-large intestine 4, liver 3, and stomach 36-before imaging. After imaging, subjective pain ratings and ratings of the de qi sensation were assessed. Compared with baseline, volunteers showed modulated brain activity under pain conditions in the cingulate gyrus, insula, primary somatosensory cortex, and prefrontal areas after the acupuncture session. In accordance with the literature, anterior insular and prefrontal activity seemed to be correlated with acupuncture treatment. This study supports the existence of analgesic acupuncture effects that outlast the needling period. Pain-associated brain areas were modulated in direct response to a preceding acupuncture treatment.

  12. Side effects of pain and analgesia in animal experimentation.

    PubMed

    Jirkof, Paulin

    2017-03-22

    This review highlights selected effects of untreated pain and of widely used analgesics such as opioids, non-steroid anti-inflammatory drugs and antipyretics, to illustrate the relevance of carefully planned, appropriate and controlled analgesia for greater reproducibility in animal experiments involving laboratory rodents.

  13. Tryptase - PAR2 axis in Experimental Autoimmune Prostatitis, a model for Chronic Pelvic Pain Syndrome

    PubMed Central

    Roman, Kenny; Done, Joseph D.; Schaeffer, Anthony J.; Murphy, Stephen F.; Thumbikat, Praveen

    2014-01-01

    Chronic prostatitis/Chronic pelvic pain syndrome (CP/CPPS) affects up to 15% of the male population and is characterized by pelvic pain. Mast cells are implicated in the murine experimental autoimmune prostatitis (EAP) model as key to chronic pelvic pain development. The mast cell mediator tryptase-β and its cognate receptor protease-activated receptor 2 (PAR2) are involved in mediating pain in other visceral disease models. Prostatic secretions and urines from CP/CPPS patients were examined for the presence of mast cell degranulation products. Tryptase-β and PAR2 expression were examined in murine experimental autoimmune prostatitis (EAP). Pelvic pain and inflammation were assessed in the presence or absence of PAR2 expression and upon PAR2 neutralization. Tryptase-β and carboxypeptidase A3 were elevated in CP/CPPS compared to healthy volunteers. Tryptase-β was capable of inducing pelvic pain and was increased in EAP along with its receptor PAR2. PAR2 was required for the development of chronic pelvic pain in EAP. PAR2 signaling in dorsal root ganglia lead to ERK1/2 phosphorylation and calcium influx. PAR2 neutralization using antibodies attenuated chronic pelvic pain in EAP. The tryptase-PAR2 axis is an important mediator of pelvic pain in EAP and may play a role in the pathogenesis of CP/CPPS. PMID:24726923

  14. Sleep Fragmentation Hypersensitizes Healthy Young Women to Deep and Superficial Experimental Pain.

    PubMed

    Iacovides, Stella; George, Kezia; Kamerman, Peter; Baker, Fiona C

    2017-07-01

    The effect of sleep deprivation on pain sensitivity has typically been studied using total and partial sleep deprivation protocols. These protocols do not mimic the fragmented pattern of sleep disruption usually observed in individuals with clinical pain conditions. Therefore, we conducted a controlled experiment to investigate the effect of sleep fragmentation on pain perception (deep pain: forearm muscle ischemia, and superficial pain: graded pin pricks applied to the skin) in 11 healthy young women after 2 consecutive nights of sleep fragmentation, compared with a normal night of sleep. Compared with normal sleep, sleep fragmentation resulted in significantly poorer sleep quality, morning vigilance, and global mood. Pin prick threshold decreased significantly (increased sensitivity), as did habituation to ischemic muscle pain (increased sensitivity), over the course of the 2 nights of sleep fragmentation compared with the night of normal sleep. Sleep fragmentation did not increase the maximum pain intensity reported during muscle ischemia (no increase in gain), and nor did it increase the number of spontaneous pains reported by participants. Our data show that sleep fragmentation in healthy, young, pain-free women increases pain sensitivity in superficial and deep tissues, indicating a role for sleep disruption, through sleep fragmentation, in modulating pain perception. Our findings that pain-free, young women develop hyperalgesia to superficial and deep muscle pain after short-term sleep disruption highlight the need for effective sleep management strategies in patients with pain. Findings also suggest the possibility that short-term sleep disruption associated with recurrent acute pain could contribute to increased risk for future chronic pain conditions. Copyright © 2017 American Pain Society. Published by Elsevier Inc. All rights reserved.

  15. Differential sensitivity of three experimental pain models in detecting the analgesic effects of transdermal fentanyl and buprenorphine.

    PubMed

    Koltzenburg, Martin; Pokorny, Rolf; Gasser, Urs E; Richarz, Ute

    2006-12-15

    This is the first randomized controlled trial that tests the analgesic efficacy of transdermally delivered opioids in healthy volunteers and that assesses the sensitivity of different experimental pain tests to detect analgesia in this setting. Transdermal application of the full agonist fentanyl (TDF: 12.5 or 25 microg/h) and the partial agonist buprenorphine (TDB: 35 microg/h) was compared in three experimental models of acute pain (heat pain, painful electrical stimulation, cold pressor) in a double-blind, randomized, placebo-controlled, 4-arm crossover study with 20 healthy subjects (15 men, 5 women). Patches were administered for 72 h and pain levels measured at baseline and 24 and 72 h, with an 11-day wash-out. The cold pressor test was most sensitive to analgesic effects, with significant reductions in area under the pain intensity curve for all active compounds at 24 h (average reductions: 14% TDF 12.5 microg/h, 35% TDF 25 microg/h, 43% TDB 35 microg/h). There were significant increases in heat pain threshold for TDF 25 microg/h and TDB 35 microg/h. Painful electrical stimulation failed to demonstrate an analgesic effect. The magnitude of analgesia in the cold pressor model showed some correlation with TDF dosage and comparable effects for the full agonist fentanyl and the partial agonist buprenorphine. We conclude that the cold pressor test was most sensitive to analgesic effects in healthy subjects and that a transdermal dose of 12.5 microg/h fentanyl achieved significant pain reduction compared with placebo. Subjects experienced opioid-typical AEs including dizziness, nausea and vomiting. No serious AEs occurred.

  16. Helicopter pilot back pain: a preliminary study.

    PubMed

    Shanahan, D F; Reading, T E

    1984-02-01

    Because of the high prevalence of back pain experienced by U.S. Army helicopter pilots, a study was conducted to ascertain the feasibility of reproducing these symptoms in the laboratory. A mock-up of a UH-1H seat and control configuration was mounted to a multi-axis vibration simulator (MAVS). Eleven subjects were tested on the apparatus for two 120-min periods. During one period, the MAVS was programmed to reproduce vibrations recorded from a UH-1H in cruise flight. The subjects received no vibration during the other test period. All subjects reported back pain which they described as identical to the pain they experience during flight, during one or more of their test periods. There was no statistical difference between the vibration and nonvibration test conditions (p greater than 0.05) in terms of time of onset of pain or intensity of pain as measured by a visual analog scale. It appears the vibration at the frequencies and amplitudes tested plays little or no role in the etiology of the back symptoms reported by these pilots. It is proposed that the primary etiological factor for these symptoms is the poor posture pilots are obliged to assume for extended periods while operating helicopters.

  17. Glenohumeral Joint Pain Referral Patterns: A Descriptive Study.

    PubMed

    Kennedy, David J; Mattie, Ryan; Nguyen, Quang; Hamilton, Scott; Conrad, Bryan

    2015-08-01

    Pain diagrams are a useful tool to help physicians understand the varying presentation patterns of specific pain generators. This study is the first to describe the potential pain patterns of the glenohumeral joint (GHJ) based on responses to diagnostic image-guided GHJ injections. To determine potential GHJ pain referral patterns. 162 consecutive patients undergoing 168 GHJ injections recorded their preprocedure pain scores and drew accurate pain diagrams prior to undergoing fluoroscopically guided GHJ injections with local anesthetic. Postprocedure pain scores were recorded and those with complete relief were considered responders. Pain diagrams were overlaid via computer software to facilitate analysis and a composite pain map. A responder composite was also compared with a nonresponder composite. The GHJ was shown to cause pain in traditionally localized areas of the anterior and/or posterior shoulder and upper arm regions in 100% of patients who experienced complete pain relief after injection. Among 100% responders, 18% had neck pain and 6% had scapular pain. Pain was shown to radiate distally, with anterior forearm pain in 9%, posterior forearm pain in 8%, and hand pain in 9%. No patients with pain both in the medial neck and below the elbow were found to be 100% responders. Similarly, no patients were 100% responders if they had pain in the medial scapula and below the elbow, or medial scapula and medial neck. Anterior or posterior shoulder and upper arm pain, or a combination of the two, is the most common pain referral area from a symptomatic shoulder joint. Referral to the lateral neck, in combination with shoulder pain, was occasionally seen. Pain referral to the forearm and hand was less common. Rarely did a symptomatic shoulder joint refer pain to the scapula or to the medial neck. Wiley Periodicals, Inc.

  18. The relationship of the audible pop to hypoalgesia associated with high-velocity, low-amplitude thrust manipulation: a secondary analysis of an experimental study in pain-free participants.

    PubMed

    Bialosky, Joel E; Bishop, Mark D; Robinson, Michael E; George, Steven Z

    2010-02-01

    High-velocity, low-amplitude (HVLA) manipulation is an effective treatment of low back pain (LBP); however, the corresponding mechanisms are undetermined. Hypoalgesia is associated with HVLA manipulation and suggests specific mechanisms of action. An audible pop (AP) is also associated with HVLA manipulation; however, the influence of the AP on the hypoalgesia associated with HVLA manipulation is not established. The purpose of the current study was to observe the influence of the AP on hypoalgesia associated with HVLA manipulation. The current study represents a secondary analysis of 40 participants. All participants underwent thermal pain sensitivity testing to their leg and low back using protocols specific to A delta fiber-mediated pain and temporal summation. Next, participants received HVLA manipulation to their low back, and the examiner recorded whether an AP was perceived. Finally, participants underwent immediate follow-up thermal pain sensitivity testing using the same protocols. Separate repeated-measure analyses of variance (ANOVAs) were used to observe changes in pain sensitivity before and immediately after HVLA manipulation. Hypoalgesia of A delta fiber-mediated pain was observed in the low back after HVLA (P < .05), and this was independent of whether an AP was perceived (P > .05). Hypoalgesia of temporal summation was observed in the lower extremity after HVLA (P < .05), and this was independent of whether an AP was perceived (P = .08). However, a moderate effect size for temporal summation was observed favoring participants in whom an AP was perceived. The current study suggests hypoalgesia is associated with HVLA manipulation and occurs independently of a perceived AP. Inhibition of lower extremity temporal summation may be larger in individuals in whom an AP is perceived, but further study is necessary to confirm this finding. (c) 2010 National University of Health Sciences. Published by Mosby, Inc. All rights reserved.

  19. Effects of experimentally induced low back pain on the sit-to-stand movement and electroencephalographic contingent negative variation

    PubMed Central

    Jacobs, Jesse V.; Yaguchi, Chie; Kaida, Chizuru; Irei, Mariko; Naka, Masami; Henry, Sharon M.; Fujiwara, Katsuo

    2011-01-01

    It is becoming increasingly evident that people with chronic, recurrent low back pain (LBP) exhibit changes in cerebrocortical activity that associate with altered postural coordination, suggesting a need for a better understanding of how the experience of LBP alters postural coordination and cerebrocortical activity. To characterize changes in postural coordination and pre-movement cerebrocortical activity related to the experience of acutely induced LBP, 14 healthy participants with no history of LBP performed sit-to-stand movements in 3 sequential conditions: (1) without experimentally induced LBP; NoPain1, (2) with movement-associated LBP induced by electrocutaneous stimulation; Pain, and (3) again without induced LBP; NoPain2. The Pain condition elicited altered muscle activation and redistributed forces under the seat and feet prior to movement, decreased peak vertical force exerted under the feet during weight transfer, longer movement times, as well as decreased and earlier peak hip extension. Stepwise regression models demonstrated that electroencephalographic amplitudes of contingent negative variation during the Pain condition significantly correlated with the participants’ change in sit-to-stand measures between the NoPain1 and Pain conditions, as well as with the subsequent difference in sit-to-stand measures between the NoPain1 and NoPain2 conditions. The results, therefore, identify the contingent negative variation as a correlate for the extent of an individual’s LBP-related movement modifications and to the subsequent change in movement patterns from before to after the experience of acutely induced LBP, thereby providing a direction for future studies aimed to understand the neural mechanisms underlying the development of altered movement patterns with LBP. PMID:21952791

  20. Satisfaction with and Perception of Pain Management among Palliative Patients with Breakthrough Pain: A Qualitative Study.

    PubMed

    Pathmawathi, Subramanian; Beng, Tan Seng; Li, Lee Mei; Rosli, Roshaslina; Sharwend, Supermanian; Kavitha, Rasaiah R; Christopher, Boey Chiong Meng

    2015-08-01

    Breakthrough pain is a significant contributor to much suffering by patients. The experience of intense pain may interfere with, and affect, daily life functioning and has major consequences on patients' well-being if it is not well managed. The area of breakthrough pain has not been fully understood. This study thus aimed to explore the experiences of breakthrough pain among palliative patients. A qualitative study based on a series of open-ended interviews among 21 palliative patients suffering from pain at an urban tertiary hospital in Malaysia was conducted. Five themes were generated: (i) pain viewed as an unbearable experience causing misery in the lives of patients, (ii) deterioration of body function and no hope of recovery, (iii) receiving of inadequate pain management for pain, (iv) insensitivity of healthcare providers toward patients' pain experience, and (v) pain coping experiences of patients. The findings revealed that nonpharmacologic approaches such as psychosocial support should be introduced to the patients. Proper guidance and information should be given to healthcare providers to improve the quality of patient care. Healthcare providers should adopt a sensitive approach in caring for patients' needs. The aim is to meet the needs of the patients who want to be pain free or to attain adequate relief of their pain for breakthrough pain.

  1. Pain Intensity and Pain Interference in patients with lung cancer: A pilot study of Biopsychosocial Predictors

    PubMed Central

    Dalton, Jo Ann; Higgins, Melinda K.; Miller, Andrew H.; Keefe, Francis J.; Khuri, Fadlo R.

    2013-01-01

    Objective To explore biopsychosocial factors (beliefs, depression, catastrophizing cytokines) in individuals newly diagnosed with lung cancer and no pain in order to determine their relationship at diagnosis and across time and to determine whether these factors contribute to pain intensity or pain interference with function at pain onset. Methods A longitudinal, exploratory, pilot study was implemented in a private medical center and a VA medical center in the southeast. Twelve subjects not experiencing pain related to cancer of the lung or its treatment were recruited. A Karnofsky status of 40% and Hemoglobin of 8 grams were required. Five questionnaires were completed and 10 cc of blood was drawn at Baseline; 4 questionnaires and blood draws were repeated monthly for 5 months. One Baseline questionnaire and a pain assessment were added at Final. Demographic, clinical and questionnaire data were summarized; standardized scale scores were calculated. Results Biopsychosocial scores that were low at Baseline increased from T1-T4 but decreased slightly T5-T6. Individuals with higher pain intensity and higher pain interference at Final had higher psychosocial scores at Baseline than individuals with lower pain intensity and lower pain interference at Final. Conclusions Unrelated to disease stage, metastasis or treatment, unique, levels of biopsychosocial factors are observed in patients newly diagnosed with lung cancer who report higher levels of Pain Intensity and higher levels of Pain Interference at the time pain occurs. Replication studies are needed to validate this response pattern and determine the value of repeated individual assessments. PMID:24064756

  2. Neuropathic pain in the orofacial region: The role of pain history. A retrospective study.

    PubMed

    Dieb, W; Moreau, N; Chemla, I; Descroix, V; Boucher, Y

    2017-06-01

    Orofacial neuropathic pain is often difficult to treat, mostly because of still unclear underlying mechanisms. The occurrence of such neuropathic pain varies depending on different factors, of which preexisting preoperative pain seems to be of high importance. The aim of this study was thus to test the hypothesis that prior history of pain could indeed be considered a risk factor for the development of orofacial neuropathic pain in the same region. The study was performed in the dental department of the Groupe Hospitalier Pitié-Salpêtrière (GHPS) in Paris, France. We investigated the presence of prior inflammatory pain before development of orofacial neuropathic pain in 56 patients. For each patient file, the following items were collected: age, gender; medical history; diagnosis; description of the pain (at time of consultation); presence or absence of prior dental treatment; date and type of dental treatment received. 41 patients (73%) of orofacial neuropathic pain patients had a history of pain compatible with an inflammatory condition; 4% (n=2) did not report any prior pain and 23% (n=13) could not remember. Among the patients with documented history of pain prior to neuropathy, 88% (n=36) received surgical treatment; 61%, (n=25) endodontic treatment and 22%, (n=9) restorative treatment. All eventually received endodontic treatment or tooth extraction. These dental treatments are compatible with the hypothesis of prior inflammatory pain in these patients. These results support the hypothesis that prior inflammatory pain could favor the development of orofacial neuropathic pain. Prevention and treatment of inflammatory trigeminal pain may therefore play a key role in preventing future neuropathic pain development. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  3. Effect of experimental stress in 2 different pain conditions affecting the facial muscles.

    PubMed

    Woda, Alain; L'heveder, Gildas; Ouchchane, Lemlih; Bodéré, Céline

    2013-05-01

    Chronic facial muscle pain is a common feature in both fibromyalgia (FM) and myofascial (MF) pain conditions. In this controlled study, a possible difference in the mode of deregulation of the physiological response to a stressing stimulus was explored by applying an acute mental stress to FM and MF patients and to controls. The effects of the stress test were observed on pain, sympathetic variables, and both tonic and reflex electromyographic activities of masseteric and temporal muscles. The statistical analyses were performed through a generalized linear model including mixed effects. Painful reaction to the stressor was stronger (P < .001) and longer (P = .011) in FM than in MF independently of a higher pain level at baseline. The stress-induced autonomic changes only seen in FM patients did not reach significance. The electromyographic responses to the stress test were strongest for controls and weakest for FM. The stress test had no effect on reflex activity (area under the curve [AUC]) or latency, although AUC was high in FM and latencies were low in both pain groups. It is suggested that FM is characterized by a lower ability to adapt to acute stress than MF. This study showed that an acute psychosocial stress triggered several changes in 2 pain conditions including an increase in pain of larger amplitude in FM than in MF pain. Similar stress-induced changes should be explored as possible mechanisms for differentiation between dysfunctional pain conditions. Copyright © 2013 American Pain Society. Published by Elsevier Inc. All rights reserved.

  4. Tryptase-PAR2 axis in experimental autoimmune prostatitis, a model for chronic pelvic pain syndrome.

    PubMed

    Roman, Kenny; Done, Joseph D; Schaeffer, Anthony J; Murphy, Stephen F; Thumbikat, Praveen

    2014-07-01

    Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) affects up to 15% of the male population and is characterized by pelvic pain. Mast cells are implicated in the murine experimental autoimmune prostatitis (EAP) model as key to chronic pelvic pain development. The mast cell mediator tryptase-β and its cognate receptor protease-activated receptor 2 (PAR2) are involved in mediating pain in other visceral disease models. Prostatic secretions and urines from CP/CPPS patients were examined for the presence of mast cell degranulation products. Tryptase-β and PAR2 expression were examined in murine EAP. Pelvic pain and inflammation were assessed in the presence or absence of PAR2 expression and upon PAR2 neutralization. Tryptase-β and carboxypeptidase A3 were elevated in CP/CPPS compared to healthy volunteers. Tryptase-β was capable of inducing pelvic pain and was increased in EAP along with its receptor PAR2. PAR2 was required for the development of chronic pelvic pain in EAP. PAR2 signaling in dorsal root ganglia led to extracellular signal-regulated kinase (ERK)1/2 phosphorylation and calcium influx. PAR2 neutralization using antibodies attenuated chronic pelvic pain in EAP. The tryptase-PAR2 axis is an important mediator of pelvic pain in EAP and may play a role in the pathogenesis of CP/CPPS.

  5. Preclinical studies of low back pain

    PubMed Central

    2013-01-01

    Chronic low back pain is a major cause of disability and health care costs. Current treatments are inadequate for many patients. A number of preclinical models have been developed that attempt to mimic aspects of clinical conditions that contribute to low back pain. These involve application of nucleus pulposus material near the lumbar dorsal root ganglia (DRG), chronic compression of the DRG, or localized inflammation of the DRG. These models, which are primarily implemented in rats, have many common features including behavioral hypersensitivity of the hindpaw, enhanced excitability and spontaneous activity of sensory neurons, and locally elevated levels of inflammatory mediators including cytokines. Clinically, epidural injection of steroids (glucocorticoids) is commonly used when more conservative treatments fail, but clinical trials evaluating these treatments have yielded mixed results. There are relatively few preclinical studies of steroid effects in low back pain models. One preclinical study suggests that the mineralocorticoid receptor, also present in the DRG, may have pro-inflammatory effects that oppose the activation of the glucocorticoid receptor. Although the glucocorticoid receptor is the target of anti-inflammatory steroids, many clinically used steroids activate both receptors. This could be one explanation for the limited effects of epidural steroids in some patients. Additional preclinical research is needed to address other possible reasons for limited efficacy of steroids, such as central sensitization or presence of an ongoing inflammatory stimulus in some forms of low back pain. PMID:23537369

  6. Assessing effects of a semi-customized experimental cervical pillow on symptomatic adults with chronic neck pain with and without headache

    PubMed Central

    Erfanian, Parham; Tenzif, Siamak; Guerriero, Rocco C

    2004-01-01

    Objective To determine the effects of a semi-customized experimental cervical pillow on symptomatic adults with chronic neck pain (with and without headache) during a four week study. Design A randomized controlled trial. Sample size Thirty-six adults were recruited for the trial, and randomly assigned to experimental or non-experimental groups of 17 and 19 participants respectively. Subjects Adults with chronic biomechanical neck pain who were recruited from the Canadian Memorial Chiropractic College (CMCC) Walk-in Clinic. Outcome measures Subjective findings were assessed using a mail-in self-report daily pain diary, and the CMCC Neck Disability Index (NDI). Statistical analysis Using repeated measure analysis of variance weekly NDI scores, average weekly AM and PM pain scores between the experimental and non-experimental groups were compared throughout the study. Results The experimental group had statistically significant lower NDI scores (p < 0.05) than the non-experimental group. The average weekly AM scores were lower and statistically significant (p < 0.05) in the experimental group. The PM scores in the experimental group were lower but not statistically significant than the other group. Conclusions The study results show that compared to conventional pillows, this experimental semi-customized cervical pillow was effective in reducing low-level neck pain intensity, especially in the morning following its use in a 4 week long study. PMID:17549216

  7. The effect of experimental pain on motor training performance and sensorimotor integration.

    PubMed

    Dancey, Erin; Murphy, Bernadette; Srbely, John; Yielder, Paul

    2014-09-01

    Experimental pain is known to affect neuroplasticity of the motor cortex as well as motor performance, but less is known about neuroplasticity of somatosensory processing in the presence of pain. Early somatosensory evoked potentials (SEPs) provide a mechanism for investigating alterations in sensory processing and sensorimotor integration (SMI). The overall aim of this study was to investigate the interactive effects of acute pain, motor training, and sensorimotor processing. Two groups of twelve participants (N = 24) were randomly assigned to either an intervention (capsaicin cream) or placebo (inert lotion) group. SEP amplitudes were collected by stimulation of the median nerve at baseline, post-application and post-motor training. Participants performed a motor sequence task while reaction time and accuracy data were recorded. The amplitude of the P22-N24 complex was significantly increased following motor training for both groups F(2,23) = 3.533, p < 0.05, while Friedman's test for the P22-N30 complex showed a significant increase in the intervention group [χ(2) (df = 2, p = 0.016) = 8.2], with no significant change in the placebo group. Following motor training, reaction time was significantly decreased for both groups F(1,23) = 59.575, p < 0.01 and overall accuracy differed by group [χ(2) (df = 3, p < 0.001) = 19.86], with post hoc testing indicating that the intervention group improved in accuracy following motor training [χ(2) (df = 1, p = 0.001) = 11.77] while the placebo group had worse accuracy [χ(2) (df = 1, p = 0.006) = 7.67]. The improved performance in the presence of capsaicin provides support for the enhancement of knowledge acquisition with the presence of nontarget stimuli. In addition, the increase in SEP peak amplitudes suggests that early SEP changes are markers of SMI changes accompanying motor training and acute pain.

  8. Effect of experimental low back pain on neuromuscular control of the trunk in healthy volunteers and patients with chronic low back pain.

    PubMed

    Dubois, Jean-Daniel; Piché, Mathieu; Cantin, Vincent; Descarreaux, Martin

    2011-10-01

    Studies of electromyographic (EMG) activity and lumbopelvic rhythm have led to a better understanding of neuromuscular alterations in chronic low back pain (cLBP) patients. Whether these changes reflect adaptations to chronic pain or are induced by acute pain is still unclear. This work aimed to assess the effects of experimental LBP on lumbar erector spinae (LES) EMG activity and lumbopelvic kinematics during a trunk flexion-extension task in healthy volunteers and LBP patients. The contribution of disability to these effects was also examined. Twelve healthy participants and 14 cLBP patients performed flexion-extension tasks in three conditions; control, innocuous heat and noxious heat, applied on the skin over L5 or T7. The results indicated that noxious heat at L5 evoked specific increases in LES activity during static full trunk flexion and extension, irrespective of participants' group. Kinematic data suggested that LBP patients adopted a different movement strategy than controls when noxious heat was applied at the L5 level. Besides, high disability was associated with less kinematic changes when approaching and leaving full flexion. These results indicate that experimental pain can induce neuromechanical alterations in cLBP patients and healthy volunteers, and that higher disability in patients is associated with decreased movement pattern changes.

  9. Experimental muscle pain increases variability of neural drive to muscle and decreases motor unit coherence in tremor frequency band

    PubMed Central

    Yavuz, Utku Ş.; Negro, Francesco; Falla, Deborah

    2015-01-01

    It has been observed that muscle pain influences force variability and low-frequency (<3 Hz) oscillations in the neural drive to muscle. In this study, we aimed to investigate the effect of experimental muscle pain on the neural control of muscle force at higher frequency bands, associated with afferent feedback (alpha band, 5–13 Hz) and with descending cortical input (beta band, 15–30 Hz). Single-motor unit activity was recorded, in two separate experimental sessions, from the abductor digiti minimi (ADM) and tibialis anterior (TA) muscles with intramuscular wire electrodes, during isometric abductions of the fifth finger at 10% of maximal force [maximum voluntary contraction (MVC)] and ankle dorsiflexions at 25% MVC. The contractions were repeated under three conditions: no pain (baseline) and after intramuscular injection of isotonic (0.9%, control) and hypertonic (5.8%, painful) saline. The results showed an increase of the relative power of both the force signal and the neural drive at the tremor frequency band (alpha, 5–13 Hz) between the baseline and hypertonic (painful) conditions for both muscles (P < 0.05) but no effect on the beta band. Additionally, the strength of motor unit coherence was lower (P < 0.05) in the hypertonic condition in the alpha band for both muscles and in the beta band for the ADM. These results indicate that experimental muscle pain increases the amplitude of the tremor oscillations because of an increased variability of the neural control (common synaptic input) in the tremor band. Moreover, the concomitant decrease in coherence suggests an increase in independent input in the tremor band due to pain. PMID:26019314

  10. Increased COX2 in the trigeminal nucleus caudalis is involved in orofacial pain induced by experimental tooth movement.

    PubMed

    Gao, Yuan; Duan, Yin-Zhong

    2010-03-01

    Pain is among the major problems during orthodontic treatment. Recent studies have shown that central Cyclooxygenase2 (COX2) pathway was involved in several pain models. The present study investigated whether inducible COX2 within the trigeminal nucleus caudalis (Vc) contributed to experimental tooth movement pain in freely moving rats. Elastic rubber bands were inserted between the first and second maxillary molars bilaterally to establish tooth movement model. The directed mouth wiping behavior was used to evaluate the pain during tooth movement. COX2 distribution in Vc was studied by immunohistochemistry and the changes of COX2 expression were detected by Western blot at different time point after rubber band insertion. Our results showed that tooth movement significantly increased COX2 expression in Vc and the time spent on mouth wiping, reaching a maximum at 1 day and then decreasing gradually. Furthermore, the rhythm change of COX2 expression in Vc and the mouth wiping behavior were much correlative with each other. All of the COX2-immunoreactive structures in Vc exhibited NeuN-immunopositive staining and most of these COX2-immunoreactive neurons were Fos-immunopositive. Importantly, the mouth wiping behavior could be attenuated by intracisternal injection of NS-398 (a selective COX2 inhibitor) but not by periodontal administration of NS-398. All these results suggested that increased COX2 in Vc was involved in tooth movement pain and thus may be a central target for orthodontic pain treatment.

  11. Fear-avoidance, pain acceptance and adjustment to chronic pain: a cross-sectional study on a sample of 686 patients with chronic spinal pain.

    PubMed

    Ramírez-Maestre, Carmen; Esteve, Rosa; López-Martínez, Alicia

    2014-12-01

    Prior studies found a range of psychological factors related to the perception of pain, maintenance of pain and disability. The aim of this study was to investigate the role of pain fear-avoidance and pain acceptance in chronic pain adjustment. The influence of two diathesis variables (resilience and experiential avoidance) was also analyzed. The sample was composed of 686 patients with chronic spinal pain. Structural equation modelling analyses were used to test the hypothetical model. Experiential avoidance was associated with pain fear-avoidance, and resilience was strongly associated with pain acceptance. Pain acceptance was negatively associated with negative mood, functional impairment and pain intensity. However, pain fear-avoidance was positively and significantly associated with negative mood but had no association with pain intensity. There was a path from functional impairment to pain fear-avoidance. Resilience and experiential avoidance appear as variables which could explain individual differences in pain experience.

  12. Comparison of Low Back Pain Recovery and Persistence: A Descriptive Study of Characteristics at Pain Onset.

    PubMed

    Starkweather, Angela R; Lyon, Debra E; Kinser, Patricia; Heineman, Amy; Sturgill, Jamie L; Deng, Xiaoyan; Siangphoe, Umaporn; Elswick, R K; Greenspan, Joel; Dorsey, Susan G

    2016-07-01

    Persistent low back pain is a significant problem worldwide. Early identification and treatment of individuals at high risk for persistent low back pain have been suggested as strategies to decrease the rate of disability associated with this condition. To examine and compare demographic, pain-related, psychological, and somatosensory characteristics in a cohort of participants with acute low back pain who later went on to experience persistent low back pain or whose pain resolved within the first 6 weeks after initial onset. A descriptive study was conducted among men and women 18-50 years of age who had an acute episode of low back pain. Study questionnaires were administered to collect demographic information and measures of pain, coping, reactivity, mood, work history and satisfaction, and disability. A standardized protocol of quantitative sensory testing was performed on each participant at the painful area of their low back and at a remote site on their arm. The sample consisted of 48 participants, of whom 19 went on to develop persistent low back pain and 29 resolved. Compared to the resolved group, the persistent low back pain group was significantly older and had a lower level of educational attainment, a higher body mass index, and higher mean "least" pain score on the Brief Pain Inventory-Short Form. Significantly higher thermal detection thresholds at the painful and remote sites as well as signs of central sensitivity differentiated the persistent pain group from the resolved group during the acute stage of low back pain. © The Author(s) 2016.

  13. A Preliminary Genome-Wide Association Study of Pain-Related Fear: Implications for Orofacial Pain.

    PubMed

    Randall, Cameron L; Wright, Casey D; Chernus, Jonathan M; McNeil, Daniel W; Feingold, Eleanor; Crout, Richard J; Neiswanger, Katherine; Weyant, Robert J; Shaffer, John R; Marazita, Mary L

    2017-01-01

    Acute and chronic orofacial pain can significantly impact overall health and functioning. Associations between fear of pain and the experience of orofacial pain are well-documented, and environmental, behavioral, and cognitive components of fear of pain have been elucidated. Little is known, however, regarding the specific genes contributing to fear of pain. A genome-wide association study (GWAS; N = 990) was performed to identify plausible genes that may predispose individuals to various levels of fear of pain. The total score and three subscales (fear of minor, severe, and medical/dental pain) of the Fear of Pain Questionnaire-9 (FPQ-9) were modeled in a variance components modeling framework to test for genetic association with 8.5 M genetic variants across the genome, while adjusting for sex, age, education, and income. Three genetic loci were significantly associated with fear of minor pain (8q24.13, 8p21.2, and 6q26; p < 5 × 10(-8) for all) near the genes TMEM65, NEFM, NEFL, AGPAT4, and PARK2. Other suggestive loci were found for the fear of pain total score and each of the FPQ-9 subscales. Multiple genes were identified as possible candidates contributing to fear of pain. The findings may have implications for understanding and treating chronic orofacial pain.

  14. A Preliminary Genome-Wide Association Study of Pain-Related Fear: Implications for Orofacial Pain

    PubMed Central

    Randall, Cameron L.; Chernus, Jonathan M.; Feingold, Eleanor; Crout, Richard J.; Weyant, Robert J.

    2017-01-01

    Background Acute and chronic orofacial pain can significantly impact overall health and functioning. Associations between fear of pain and the experience of orofacial pain are well-documented, and environmental, behavioral, and cognitive components of fear of pain have been elucidated. Little is known, however, regarding the specific genes contributing to fear of pain. Methods A genome-wide association study (GWAS; N = 990) was performed to identify plausible genes that may predispose individuals to various levels of fear of pain. The total score and three subscales (fear of minor, severe, and medical/dental pain) of the Fear of Pain Questionnaire-9 (FPQ-9) were modeled in a variance components modeling framework to test for genetic association with 8.5 M genetic variants across the genome, while adjusting for sex, age, education, and income. Results Three genetic loci were significantly associated with fear of minor pain (8q24.13, 8p21.2, and 6q26; p < 5 × 10−8 for all) near the genes TMEM65, NEFM, NEFL, AGPAT4, and PARK2. Other suggestive loci were found for the fear of pain total score and each of the FPQ-9 subscales. Conclusions Multiple genes were identified as possible candidates contributing to fear of pain. The findings may have implications for understanding and treating chronic orofacial pain. PMID:28701861

  15. High- and low-frequency transcutaneous electrical nerve stimulation does not reduce experimental pain in elderly individuals

    PubMed Central

    Bergeron-Vézina, Kayla; Corriveau, Hélène; Martel, Marylie; Harvey, Marie-Philippe; Léonard, Guillaume

    2015-01-01

    Abstract Despite its widespread clinical use, the efficacy of transcutaneous electrical nerve stimulation (TENS) remains poorly documented in elderly individuals. In this randomized, double-blind crossover study, we compared the efficacy of high-frequency (HF), low-frequency (LF), and placebo (P) TENS in a group of 15 elderly adults (mean age: 67 ± 5 years). The effect of HF-, LF-, and P-TENS was also evaluated in a group of 15 young individuals (26 ± 5 years; same study design) to validate the effectiveness of the TENS protocols that were used in the elderly group. Each participant came to the laboratory on 3 separate occasions to receive, in random order, HF-, LF-, and P-TENS. Pain intensity and pain perception thresholds were assessed before, during, and after TENS, using an experimental heat pain paradigm. For the young group, there was a significant decrease in pain intensity during and after HF- and LF-TENS when compared with baseline, with both HF- and LF-TENS being superior to P-TENS. In the older group, HF- and LF-TENS did not reduce pain when compared with baseline and no difference was observed between the 2 active TENS sessions and P-TENS. High-frequency, LF-, and P-TENS all increased pain thresholds in young individuals, whereas in older individuals, only LF-TENS increased pain thresholds. Taken together, these results suggest that TENS is effective in young, but not in older, individuals. Future studies should be conducted to confirm these results in pain populations and to identify strategies that could enhance the effect of TENS in the elderly. PMID:26101836

  16. High- and low-frequency transcutaneous electrical nerve stimulation does not reduce experimental pain in elderly individuals.

    PubMed

    Bergeron-Vézina, Kayla; Corriveau, Hélène; Martel, Marylie; Harvey, Marie-Philippe; Léonard, Guillaume

    2015-10-01

    Despite its widespread clinical use, the efficacy of transcutaneous electrical nerve stimulation (TENS) remains poorly documented in elderly individuals. In this randomized, double-blind crossover study, we compared the efficacy of high-frequency (HF), low-frequency (LF), and placebo (P) TENS in a group of 15 elderly adults (mean age: 67 ± 5 years). The effect of HF-, LF-, and P-TENS was also evaluated in a group of 15 young individuals (26 ± 5 years; same study design) to validate the effectiveness of the TENS protocols that were used in the elderly group. Each participant came to the laboratory on 3 separate occasions to receive, in random order, HF-, LF-, and P-TENS. Pain intensity and pain perception thresholds were assessed before, during, and after TENS, using an experimental heat pain paradigm. For the young group, there was a significant decrease in pain intensity during and after HF- and LF-TENS when compared with baseline, with both HF- and LF-TENS being superior to P-TENS. In the older group, HF- and LF-TENS did not reduce pain when compared with baseline and no difference was observed between the 2 active TENS sessions and P-TENS. High-frequency, LF-, and P-TENS all increased pain thresholds in young individuals, whereas in older individuals, only LF-TENS increased pain thresholds. Taken together, these results suggest that TENS is effective in young, but not in older, individuals. Future studies should be conducted to confirm these results in pain populations and to identify strategies that could enhance the effect of TENS in the elderly.

  17. Chemokine ligand 2 in the trigeminal ganglion regulates pain induced by experimental tooth movement.

    PubMed

    Yang, Zhi; Luo, Wei; Wang, Jing; Tan, Yu; Fu, Runqing; Fang, Bing

    2014-07-01

    To test the hypothesis that the chemokine ligand 2/chemokine receptor 2 (CCL2/CCR2) signaling pathway plays an important role in pain induced by experimental tooth movement. Expression of CCL2/CCR2 in the trigeminal ganglion (TG) was determined by Western blotting 0 hours, 4 hours, 1 day, 3 days, 5 days, and 7 days after tooth movement. CCL2 localization and cell size distribution were revealed by immunohistochemistry. The effects of increasing force on CCL2 expression and behavioral changes were investigated. Furthermore, the effects of CCL2/CCR2 antagonists on these changes in pain behaviors were all evaluated. Exogenous CCL2 was injected into periodontal tissues and cultured TG neurons with different concentrations, and then the pain responses or c-fos expression were assessed. Experimental tooth movement led to a statistically significant increase in CCL2/CCR2 expression from day 3 to day 7, especially in small to medium-sized TG neurons. It also triggered an increase in the time spent on directed face-grooming behaviors in a force magnitude-dependent and CCL2 dose-dependent manner. Pain induced by experimental tooth movement was effectively blocked by a CCR2 antagonist and by CCL2 neutralizing antibody. Also, exogenous CCL2 led to an increase in c-fos expression in cultured TG neurons, which was blocked by CCL2 neutralizing antibody. The peripheral CCL2/CCR2 axis is modulated by experimental tooth movement and involved in the development of tooth movement pain.

  18. Effects of Experimental Pain and Lidocaine on Mechanical Somatosensory Profile and Face Perception.

    PubMed

    Costa, Yuri Martins; Castrillon, Eduardo E; Bonjardim, Leonardo Rigoldi; Rodrigues Conti, Paulo César; Baad-Hansen, Lene; Svensson, Peter

    2017-01-01

    To assess the effects of experimental muscle pain and topical lidocaine applied to the skin overlying the masseter muscle on the mechanical somatosensory profile and face perception of the masseter muscle in healthy participants. A total of 28 healthy participants received a 45-minute application of a lidocaine or placebo patch to the skin overlying the masseter muscle followed by one injection of 0.2 mL sterile solution of monosodium glutamate. Measurements were taken four times during each session of quantitative sensory testing (QST) (T0 = baseline, T1 = 45 minutes after patch application, T2 = immediately after glutamate injection, and T3 = 25 minutes after the glutamate injection), and the following variables were measured: mechanical detection threshold (MDT), mechanical pain threshold (MPT), pressure pain threshold (PPT), pain report (pain on palpation, pain spreading on palpation, and pain intensity), pain drawing, and perceptual distortion. Multi-way within-subjects analysis of variance (ANOVA) was applied to the data. The highest MDTs were present at T2 (F = 49.28, P < .001), the lowest PPTs were present at T2 and T3 (F = 21.78, P < .001), and the largest magnitude and area of perceptual distortion were reported at T2 (F > 6.48, P < .001). Short-lasting experimental muscle pain was capable of causing loss of tactile sensitivity as well as perceptual distortion of the face, regardless of preconditioning with a topical lidocaine patch. Short-term application of a lidocaine patch did not significantly affect the mechanical somatosensory profile.

  19. Imaging studies in patients with spinal pain

    PubMed Central

    Ferrari, Robert

    2016-01-01

    Abstract Objective To evaluate an a priori threshold for advanced imaging in patients with spinal pain. Design Patients with spinal pain in any region for 6 to 52 weeks were assessed to determine if radiologic studies beyond x-ray scans were indicated, including magnetic resonance imaging (MRI), computed tomography (CT), and radionuclide bone scans. An a priori threshold was set before MRI, CT, or bone scans would be considered. Those who did not have MRI, CT, or bone scans ordered were followed for at least 1 year to determine if any of them went on to be diagnosed with a more serious spinal disorder (eg, infection, fracture, spondylitis, tumour, neurologic compression). Setting Four large primary care clinics in Edmonton, Alta. Participants A total of 1003 consecutively presenting patients with symptoms suspected to be related to the spine (for a duration of generally 6 to 52 weeks) who had not already undergone advanced imaging and did not have a diagnosis of nonbenign back pain. Main outcome measures Number of cases of nonbenign spinal disorder in participants who underwent advanced imaging and participants who did not undergo advanced imaging (ie, did not have any red flags). Results There were 399 women (39.8%) and 604 men (60.2%). The mean (SD) age of the group was 47.2 (14.6) years. The mean (SD) duration of symptoms was 15.1 (8.6) weeks. Of the 1003 participants, 110 met an a priori threshold for undergoing at least 1 of MRI, CT, or bone scan. In these 110 participants, there were newly diagnosed cases of radiculopathy (n = 12), including a case of cauda equina syndrome; spondyloarthropathy (n = 6); occult fracture (n = 2); solitary metastasis (n = 1); epidural lipomatosis (n = 1); osteomyelitis (n = 1), and retroperitoneal hematoma (n = 1), each of which was considered likely to be the cause of the patient’s spinal symptoms. The remaining 893 participants were followed for at least 1 year and none showed evidence of a nonbenign cause of his or her

  20. Improving Pain Management and Long-Term Outcomes Following High-Energy Orthopaedic Trauma (Pain Study).

    PubMed

    Castillo, Renan C; Raja, Srinivasa N; Frey, Katherine P; Vallier, Heather A; Tornetta, Paul; Jaeblon, Todd; Goff, Brandon J; Gottschalk, Allan; Scharfstein, Daniel O; OʼToole, Robert V

    2017-04-01

    Poor pain control after orthopaedic trauma is a predictor of physical disability and numerous negative long-term outcomes. Despite increased awareness of the negative consequences of poorly controlled pain, analgesic therapy among hospitalized patients after orthopaedic trauma remains inconsistent and often inadequate. The Pain study is a 3 armed, prospective, double-blind, multicenter randomized trial designed to evaluate the effect of standard pain management versus standard pain management plus perioperative nonsteroidal anti-inflammatory drugs or pregabalin in patients of ages 18-85 with extremity fractures. The primary outcomes are chronic pain, opioid utilization during the 48 hours after definitive fixation and surgery for nonunion in the year after fixation. Secondary outcomes include preoperative and postoperative pain intensity, adverse events and complications, physical function, depression, and post-traumatic stress disorder. One year treatment costs are also compared between the groups.

  1. Experimentally induced masseter-pain changes masseter but not sternocleidomastoid muscle-related activity during mastication.

    PubMed

    Pasinato, Fernanda; Santos-Couto-Paz, Clarissa C; Zeredo, Jorge Luis Lopes; Macedo, Sergio Bruzadelli; Corrêa, Eliane C R

    2016-12-01

    The aim of this study was to verify the effects of induced masseter-muscle pain on the amplitude of muscle activation, symmetry and coactivation of jaw- and neck-muscles during mastication. Twenty-eight male volunteers, mean age±SD 20.6±2.0years, participated in this study. Surface electromyography of the masseter and sternocleidomastoid (SCM) muscles was performed bilaterally during mastication of a gummy candy before and after injections of monosodium glutamate solution and isotonic saline solution. As a result, we observed a decrease in the amplitude of activation of the masseter muscle on the working side (p=0.009; d=0.34) and a reduction in the asymmetry between the working and the balancing side during mastication (p=0.007; d=0.38). No changes were observed either on the craniocervical electromyographic variables. In conclusion, experimentally induced pain reduced the masseter muscle activation on the working side, thereby reducing the physiological masseters' recruitment asymmetry between the two sides during mastication. No effects on SCM activity were detected. These results may partly explain the initial maladaptative changes underlying TMD conditions.

  2. An experimental investigation of the role of perceived justice in acute pain.

    PubMed

    McParland, J; Knussen, C; Lawrie, J; Brodie, E

    2013-03-01

    Emerging research suggests that perceiving injustice can compound the suffering of chronic pain, while perceiving justice serves as a positive psychological resource in this context. However, little more is currently known about the function of justice beliefs, particularly in the context of acute pain. The present study undertook this investigation, using cold pressor methodology to investigate whether trusting in the fairness of the world would help someone to cope with short-term pain. Sixty-five men and 65 women completed measures of personal and general just world beliefs and state anxiety before pain induction and measures of the intensity and quality of pain, in addition to state anxiety following pain induction. The personal and general beliefs in a just world were negatively correlated with pre-task anxiety but not with measures of pain induction (threshold, tolerance and sensitivity) or measures of post-task pain. Gender had a moderating role, whereby men with a stronger general just world belief reported lower post-task state anxiety and men who had a stronger personal just world belief reported lower pain intensity. However, unexpectedly, women with a stronger personal just world belief reported higher pain intensity. The observed gender differences may be attributed to gender variations in cognitive appraisals of the task. Overall, while perceived injustice may be undesirable and a potential target for intervention, perceived justice is not necessarily a desired cognition in pain. Research is needed to replicate and extend this emerging research. © 2012 European Federation of International Association for the Study of Pain Chapters.

  3. Sensory Re-Weighting in Human Bipedal Postural Control: The Effects of Experimentally-Induced Plantar Pain.

    PubMed

    Pradels, Antoine; Pradon, Didier; Hlavačková, Petra; Diot, Bruno; Vuillerme, Nicolas

    2013-01-01

    The present study was designed to assess the effects of experimentally-induced plantar pain on the displacement of centre of foot pressure during unperturbed upright stance in different sensory conditions of availability and/or reliability of visual input and somatosensory input from the vestibular system and neck. To achieve this goal, fourteen young healthy adults were asked to stand as still as possible in three sensory conditions: (1) No-vision, (2) Vision, and (3) No-vision - Head tilted backward, during two experimental conditions: (1) a No-pain condition, and (2) a condition when a painful stimulation was applied to the plantar surfaces of both feet (Plantar-pain condition). Centre of foot pressure (CoP) displacements were recorded using a force platform. Results showed that (1) experimentally-induced plantar pain increased CoP displacements in the absence of vision (No-vision condition), (2) this deleterious effect was more accentuated when somatosensory information from the vestibular and neck was altered (No-vision - Head tilted backward condition) and (3) this deleterious effect was suppressed when visual information was available (Vision condition). From a fundamental point of view, these results lend support to the sensory re-weighting hypothesis whereby the central nervous system dynamically and selectively adjusts the relative contributions of sensory inputs (i.e. the sensory weightings) in order to maintain balance when one or more sensory channels are altered by the task (novel or challenging), environmental or individual conditions. From a clinical point of view, the present findings further suggest that prevention and treatment of plantar pain may be relevant for the preservation or improvement of balance control, particularly in situations (or individuals) in which information provided by the visual, neck proprioceptive and vestibular systems is unavailable or disrupted.

  4. Sensory Re-Weighting in Human Bipedal Postural Control: The Effects of Experimentally-Induced Plantar Pain

    PubMed Central

    Pradels, Antoine; Pradon, Didier; Hlavačková, Petra; Diot, Bruno; Vuillerme, Nicolas

    2013-01-01

    The present study was designed to assess the effects of experimentally-induced plantar pain on the displacement of centre of foot pressure during unperturbed upright stance in different sensory conditions of availability and/or reliability of visual input and somatosensory input from the vestibular system and neck. To achieve this goal, fourteen young healthy adults were asked to stand as still as possible in three sensory conditions: (1) No-vision, (2) Vision, and (3) No-vision – Head tilted backward, during two experimental conditions: (1) a No-pain condition, and (2) a condition when a painful stimulation was applied to the plantar surfaces of both feet (Plantar-pain condition). Centre of foot pressure (CoP) displacements were recorded using a force platform. Results showed that (1) experimentally-induced plantar pain increased CoP displacements in the absence of vision (No-vision condition), (2) this deleterious effect was more accentuated when somatosensory information from the vestibular and neck was altered (No-vision – Head tilted backward condition) and (3) this deleterious effect was suppressed when visual information was available (Vision condition). From a fundamental point of view, these results lend support to the sensory re-weighting hypothesis whereby the central nervous system dynamically and selectively adjusts the relative contributions of sensory inputs (i.e. the sensory weightings) in order to maintain balance when one or more sensory channels are altered by the task (novel or challenging), environmental or individual conditions. From a clinical point of view, the present findings further suggest that prevention and treatment of plantar pain may be relevant for the preservation or improvement of balance control, particularly in situations (or individuals) in which information provided by the visual, neck proprioceptive and vestibular systems is unavailable or disrupted. PMID:23840337

  5. Effect of Experimental Hand Pain on Training-Induced Changes in Motor Performance and Corticospinal Excitability

    PubMed Central

    Mavromatis, Nicolas; Neige, Cécilia; Gagné, Martin; Reilly, Karen T.; Mercier, Catherine

    2017-01-01

    Pain influences plasticity within the sensorimotor system and the aim of this study was to assess the effect of pain on changes in motor performance and corticospinal excitability during training for a novel motor task. A total of 30 subjects were allocated to one of two groups (Pain, NoPain) and performed ten training blocks of a visually-guided isometric pinch task. Each block consisted of 15 force sequences, and subjects modulated the force applied to a transducer in order to reach one of five target forces. Pain was induced by applying capsaicin cream to the thumb. Motor performance was assessed by a skill index that measured shifts in the speed–accuracy trade-off function. Neurophysiological measures were taken from the first dorsal interosseous using transcranial magnetic stimulation. Overall, the Pain group performed better throughout the training (p = 0.03), but both groups showed similar improvements across training blocks (p < 0.001), and there was no significant interaction. Corticospinal excitability in the NoPain group increased halfway through the training, but this was not observed in the Pain group (Time × Group interaction; p = 0.01). These results suggest that, even when pain does not negatively impact on the acquisition of a novel motor task, it can affect training-related changes in corticospinal excitability. PMID:28165363

  6. Effect of Experimental Hand Pain on Training-Induced Changes in Motor Performance and Corticospinal Excitability.

    PubMed

    Mavromatis, Nicolas; Neige, Cécilia; Gagné, Martin; Reilly, Karen T; Mercier, Catherine

    2017-02-04

    Pain influences plasticity within the sensorimotor system and the aim of this study was to assess the effect of pain on changes in motor performance and corticospinal excitability during training for a novel motor task. A total of 30 subjects were allocated to one of two groups (Pain, NoPain) and performed ten training blocks of a visually-guided isometric pinch task. Each block consisted of 15 force sequences, and subjects modulated the force applied to a transducer in order to reach one of five target forces. Pain was induced by applying capsaicin cream to the thumb. Motor performance was assessed by a skill index that measured shifts in the speed-accuracy trade-off function. Neurophysiological measures were taken from the first dorsal interosseous using transcranial magnetic stimulation. Overall, the Pain group performed better throughout the training (p = 0.03), but both groups showed similar improvements across training blocks (p < 0.001), and there was no significant interaction. Corticospinal excitability in the NoPain group increased halfway through the training, but this was not observed in the Pain group (Time × Group interaction; p = 0.01). These results suggest that, even when pain does not negatively impact on the acquisition of a novel motor task, it can affect training-related changes in corticospinal excitability.

  7. The role of executive functioning in children's attentional pain control: an experimental analysis.

    PubMed

    Verhoeven, Katrien; Dick, Bruce; Eccleston, Christopher; Goubert, Liesbet; Crombez, Geert

    2014-02-01

    Directing attention away from pain is often used in children's pain treatment programs to control pain. However, empirical evidence concerning its effectiveness is inconclusive. We therefore sought to understand other influencing factors, including executive function and its role in the pain experience. This study investigates the role of executive functioning in the effectiveness of distraction. School children (n=164) completed executive functioning tasks (inhibition, switching, and working memory) and performed a cold-pressor task. One half of the children simultaneously performed a distracting tone-detection task; the other half did not. Results showed that participants in the distraction group were engaged in the distraction task and were reported to pay significantly less attention to pain than controls. Executive functioning influenced distraction task engagement. More specifically, participants with good inhibition and working memory abilities performed the distraction task better; participants with good switching abilities reported having paid more attention to the distraction task. Furthermore, distraction was found to be ineffective in reducing pain intensity and affect. Executive functioning did not influence the effectiveness of distraction. However, a relationship was found between executive functioning and pain affect, indicating that participants with good inhibition and working memory abilities experienced the cold-pressor task as less stressful and unpleasant. Our findings suggest that distraction as a process for managing pain is complex. While it appears that executive function may play a role in adult distraction, in this study it did not direct attention away from pain. It may instead be involved in the overall pain experience. Copyright © 2013 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

  8. Temporal changes in cortical activation during distraction from pain: a comparative LORETA study with conditioned pain modulation.

    PubMed

    Moont, Ruth; Crispel, Yonatan; Lev, Rina; Pud, Dorit; Yarnitsky, David

    2012-01-30

    Methods to cognitively distract subjects from pain and experimental paradigms to induce conditioned pain modulation (CPM; formerly termed diffuse noxious inhibitory controls or DNIC) have each highlighted activity changes in closely overlapping cortical areas. This is the first study, to our knowledge, to compare cortical activation changes during these 2 manipulations in the same experimental set-up. Our study sample included thirty healthy young right handed males capable of expressing CPM. We investigated brief consecutive time windows using 32-channel EEG-based sLORETA, to determine dynamic changes in localized cortical potentials evoked by phasic noxious heat stimuli to the left volar forearm. This was performed under visual cognitive distraction tasks and conditioning hot-water pain to the right hand (CPM), both individually and simultaneously. Previously we have shown that for CPM, there is increased activity in frontal cortical regions followed by reduced activation of the somatosensory areas, suggesting a pain inhibitory role for these frontal regions. We now observed that distraction caused a different extent of cortical activation; greater early activation of frontal areas (DLPFC, OFC and caudal ACC at 250-350 ms post-stimulus), yet lesser reduction in the somatosensory cortices, ACC, PCC and SMA after 350 ms post-stimulus, compared to CPM. Both CPM and distraction reduced subjective pain scores to a similar extent. Combining CPM and distraction further reduced pain ratings compared to CPM and distraction alone, supporting the dissimilarity of the mechanisms of pain modulation under these 2 manipulations. The results are discussed in terms of the differential functional roles of the prefrontal cortex. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. Brief relaxation training is not sufficient to alter tolerance to experimental pain in novices

    PubMed Central

    Norman, Greg J.

    2017-01-01

    Relaxation techniques, such as deep breathing and muscle relaxation, are aspects common to most forms of mindfulness training. There is now an abundance of research demonstrating that mindfulness training has beneficial effects across a wide range of clinical conditions, making it an important tool for clinical intervention. One area of extensive research is on the beneficial effects of mindfulness on experiences of pain. However, the mechanisms of these effects are still not well understood. One hypothesis is that the relaxation components of mindfulness training, through alterations in breathing and muscle tension, leads to changes in parasympathetic and sympathetic nervous system functioning which influences pain circuits. The current study seeks to examine how two of the relaxation subcomponents of mindfulness training, deep breathing and muscle relaxation, influence experiences of pain in healthy individuals. Participants were randomized to either a 10 minute deep breathing, progressive muscle relaxation, or control condition after which they were exposed to a cold pain task. Throughout the experiment, measures of parasympathetic and sympathetic nervous system activity were collected to assess how deep breathing and progressive muscle relaxation alter physiological responses, and if these changes moderate any effects of these interventions on responses to pain. There were no differences in participants’ pain tolerances or self-reported pain ratings during the cold pain task or in participants’ physiological responses to the task. Additionally, individual differences in physiological functioning were not related to differences in pain tolerance or pain ratings. Overall this study suggests that the mechanisms through which mindfulness exerts its effects on pain are more complex than merely through physiological changes brought about by altering breathing or muscle tension. This indicates a need for more research examining the specific subcomponents of

  10. Understanding venous leg ulcer pain: results of a longitudinal study.

    PubMed

    Nemeth, Kathleen A; Harrison, Margaret B; Graham, Ian D; Burke, Sharon

    2004-01-01

    Venous leg ulcer pain experienced during compression bandaging is poorly understood. A prospective, pilot cohort study was initiated to determine the feasibility of conducting a large-scale, repeated measures cohort study of venous leg ulcer pain and to document and describe the venous leg ulcer pain experience during the first 5 weeks of treatment with compression bandages. Eligible individuals admitted to a nurse-led community leg ulcer service in one Canadian community were recruited for the 5-week study. Pain assessment tools (ie, numerical rating scale and short form McGill Pain Questionnaire) were evaluated by 20 venous ulcer patients (mean age = 73.7 years) and their nurses for ease of use during one baseline and five weekly follow-up visits. Health-related quality of life (HRQL) information was obtained. Nurses reported on ease of integrating pain data collection into regular clinical care. Each pain assessment tool was audited for completion. Most participants found the pain assessment tools easy to use, but nurses reported lengthened visit times with some participants as a result of tool administration difficulties, particularly the visual analogue scale (VAS). Overall completeness of pain assessment tools ranged from 85.0% (visual analogue scale) to 96.3% (present pain intensity and word descriptor list). The vast majority of patients (18) reported ulcer pain at baseline. Total mean scores for all pain assessment tools used decreased over time, but most patients reported pain throughout the study. The most common pain descriptors used were "aching," "stabbing," "sharp," "tender," and "tiring." Health-related quality of life was low and did not change during the 5-week study. The results of this study suggest that the vast majority of venous ulcer patients experience pain and that it is feasible to examine this pain in individuals receiving care in the community over time.

  11. Granulocyte-macrophage colony-stimulating factor is a key mediator in experimental osteoarthritis pain and disease development

    PubMed Central

    2012-01-01

    Introduction Granulocyte-macrophage colony-stimulating factor (GM-CSF) has been shown to be important in the development of inflammatory models of rheumatoid arthritis and there is encouraging data that its blockade may have clinical relevance in patients with rheumatoid arthritis. The aims of the current study were to determine whether GM-CSF may also be important for disease and pain development in a model of osteoarthritis. Methods The role of GM-CSF was investigated using the collagenase-induced instability model of osteoarthritis. We studied both GM-CSF-/- mice and wild-type (C57BL/6) mice treated prophylactically or therapeutically with a monoclonal antibody to GM-CSF. Disease development (both early and late) was evaluated by histology and knee pain development was measured by assessment of weight distribution. Results In the absence of GM-CSF, there was less synovitis and matrix metalloproteinase-mediated neoepitope expression at week 2 post disease induction, and less cartilage damage at week 6. GM-CSF was absolutely required for pain development. Therapeutic neutralization of GM-CSF not only abolished the pain within 3 days but also led to significantly reduced cartilage damage. Conclusions GM-CSF is key to the development of experimental osteoarthritis and its associated pain. Importantly, GM-CSF neutralization by a therapeutic monoclonal antibody-based protocol rapidly and completely abolished existing arthritic pain and suppressed the degree of arthritis development. Our results suggest that it would be worth exploring the importance of GM-CSF for pain and disease in other osteoarthritis models and perhaps clinically for this form of arthritis. PMID:22995428

  12. Effect of Catechol-O-methyltransferase-gene (COMT) Variants on Experimental and Acute Postoperative Pain in 1,000 Women undergoing Surgery for Breast Cancer

    PubMed Central

    Kambur, Oleg; Kaunisto, Mari A.; Tikkanen, Emmi; Leal, Suzanne M.; Ripatti, Samuli; Kalso, Eija A.

    2016-01-01

    Background Catechol-O-methyltransferase (COMT) metabolizes catecholamines in different tissues. Polymorphisms in COMT gene can attenuate COMT activity and increase sensitivity to pain. Human studies exploring the effect of COMT polymorphisms on pain sensitivity have mostly included small, heterogeneous samples and have ignored several important single nucleotide polymorphisms (SNPs). This study examines the effect of COMT polymorphisms on experimental and postoperative pain phenotypes in a large ethnically homogeneous female patient cohort. Methods Intensity of cold (+2–4°C) and heat (+48°C) pain and tolerance to cold pain were assessed in 1,000 patients scheduled for breast cancer surgery. Acute postoperative pain and oxycodone requirements were recorded. Twenty-two COMT SNPs were genotyped and their association with six pain phenotypes analyzed with linear regression. Results There was no association between any of the tested pain phenotypes and SNP rs4680. The strongest association signals were seen between rs165774 and heat pain intensity as well as rs887200 and cold pain intensity. In both cases, minor allele carriers reported less pain. Neither of these results remained significant after strict multiple testing corrections. When analyzed further, the effect of rs887200 was, however, shown to be significant and consistent throughout the cold pressure test. No evidence of association between the SNPs and postoperative oxycodone consumption was found. Conclusions SNPs rs887200 and rs165774 located in the untranslated regions of the gene had the strongest effects on pain sensitivity. Their effect on pain is described here for the first time. These results should be confirmed in further studies and the potential functional mechanisms of the variants studied. PMID:24343288

  13. Emotional stress- and pain-related behaviors evoked by experimental tooth movement.

    PubMed

    Yozgatian, Joseph H; Zeredo, Jorge L; Hotokezaka, Hitoshi; Koga, Yoshiyuki; Toda, Kazuo; Yoshida, Noriaki

    2008-05-01

    To investigate by behavioral methods the relationship between emotional stress and pain during experimental tooth movement in rats. Sixteen male Sprague-Dawley rats (210 to 250 g) were divided into two groups. The experimental group was treated with an active Ti-Ni appliance, and the control group received a passive appliance. A force of 20 gf was delivered by the active appliance between the maxillary first and second molars for 3 days. During this period the rat's behavior was evaluated eight times by means of open-field test and resistance-to-capture test. The specific parameters of animal activity were facial grooming, rearing, and locomotor activity, movement into the center of the open field, and response to capture. Parameters related to stress and pain were higher in the group carrying active appliance, compared to the group with a passive appliance. Statistically significant differences in stress-related behavior between control and experimental groups were found 8 hours after placing the appliance and were most evident on the second day. Pain-related behavior was significantly greater in the experimental group than in the control group at 24 hours. The increase in emotional stress evoked by orthodontic tooth movement may precede the appearance of periodontal pain.

  14. Racial bias in pain perception and response: experimental examination of automatic and deliberate processes

    PubMed Central

    Mathur, Vani A.; Richeson, Jennifer A.; Paice, Judith A.; Muzyka, Michael; Chiao, Joan Y.

    2014-01-01

    Racial disparities in pain treatment pose a significant public health and scientific problem. Prior studies demonstrate clinicians and non-clinicians are less perceptive, and suggest less treatment for, the pain of African Americans, relative to European Americans. Here we investigate the effects of explicit/implicit patient race presentation, patient race, and perceiver race on pain perception and response. African American and European American participants rated pain perception, empathy, helping motivation, and treatment suggestion in response to vignettes about patients’ pain. Vignettes were accompanied by a rapid (implicit), or static (explicit) presentation of an African or European American patient’s face. Participants perceived and responded more to European American patients in the implicit prime condition, when the effect of patient race was below the level of conscious regulation. This effect was reversed when patient race was presented explicitly. Additionally, female participants perceived and responded more to the pain of all patients, relative to male participants, and in the implicit prime condition, African American participants were more perceptive and responsive than European Americans to the pain of all patients. Taken together, these results suggest that known disparities in pain treatment may be largely due to automatic (below the level of conscious regulation), rather than deliberate (subject to conscious regulation) biases. These biases were not associated with traditional implicit measures of racial attitudes, suggesting that biases in pain perception and response may be independent of general prejudice. Perspective Results suggest racial biases in pain perception and treatment are at least partially due to automatic processes. When the relevance of patient race is made explicit, however, biases are attenuated and even reversed. We also find preliminary evidence that African Americans may be more sensitive to the pain of others than

  15. Influence of preoperative pain intensity on postoperative pain after root canal treatment: A prospective clinical study.

    PubMed

    Alí, Akram; Olivieri, Juan Gonzalo; Duran-Sindreu, Fernando; Abella, Francesc; Roig, Miguel; García-Font, Marc

    2016-02-01

    The aim of this prospective study was to investigate the correlation between the intensity of preoperative pain and the presence of postoperative pain, taking into account the variables sex, tooth type, arch, and tooth vitality. Two hundred and seventy patients with pulpal pathology who were scheduled for routine endodontic treatment were enrolled in this study. Conventional endodontic treatment was carried out in a single visit. The chemomechanical preparation of root canals was performed with ProTaper instruments, and canals were obturated with a warm gutta-percha obturation technique. A structured questionnaire was used to record data on sex, age, type of tooth, location and pulp diagnosis. Patients were asked to record their preoperative and postoperative pain using a 10-cm visual analogue scale (VAS). Postoperative pain and the need for analgesic consumption were assessed at 4, 8, 16, 24, 48 and 72h post-treatment. The data were analyzed using the Mann-Whitney U and chi-square test, and the significance was set at P<.05. The mean level of pain after root canal treatment was 2.58±2.80 on a VAS between 0 and 10. Variables that were associated with a higher preoperative pain intensity (female, mandible and molar) also had a higher value of postoperative pain (P>.05). Within the limitations of this study, it can be concluded that the presence of preoperative pain is the variable that most influences the prevalence of postoperative pain. Pain management should be an integral part of dental treatment. The present study analyses the incidence of postoperative pain that should be expected by patients with different intensity of pain before root canal treatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Increased spinal pain sensitization in major depressive disorder: A pilot study.

    PubMed

    Tikàsz, Andràs; Tourjman, Valérie; Chalaye, Philippe; Marchand, Serge; Potvin, Stéphane

    2016-12-30

    Although patients suffering from major depressive disorder (MDD) often complain from painful symptoms, the relationship between experimental pain processes and depression has yet to be clearly characterized. Only recently have studies employing temporal summation (TS) paradigms offered preliminary insight into the co-occurrence of pain and depression. This study sets out to evaluate the contribution of spinal and supraspinal processes in pain sensitization in MDD using a TS paradigm. Thirteen volunteers with no psychiatric disorders (controls) and fourteen MDD subjects were included in the analysis. Low-(0.14Hz) and high-(1Hz) frequency intermittent stimulations of the sural nerve were used to induce TS. Spinal pain sensitization was quantified by measuring the change in the amplitude of the nociceptive-specific flexion reflex (NFR) response, and supraspinal pain sensitization was obtained by measuring change in subjective pain rating, from the low- to high-frequency stimulation condition. We found an increased sensitization in the NFR response (p<0.05) in MDD subjects in the high-frequency condition, which did not translate into an increase of their subjective responses. However, we found a positive association between spinal sensitization and painful somatic symptoms in MDD subjects. Together, these results suggest increased spinal pain sensitization in MDD, which might explain the high prevalence of painful somatic symptoms in these patients. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  17. Association Between Borderline Personality Features and Temporal Summation of Second Pain: A Cross-Sectional Study.

    PubMed

    You, Dokyoung S; Meagher, Mary W

    2017-01-01

    Individuals with greater borderline personality features may be vulnerable to chronic pain. Because pain is an unpleasant sensory and emotional experience, affect dysregulation as the core personality feature may be linked to pain hypersensitivity. Studies have found that greater borderline features are associated with increased intensity in clinical and experimental pain, and that depression mediates this increase. The current study further examined the association between borderline features and heat pain sensitivity, the contribution of affect dysregulation and the other borderline personality factors (identity problems, negative relationships, self-harming/impulsivity) to the association, and depression as a mediator. Additionally, we examined whether blunted sympathetic responses mediate the association between borderline features and temporal summation of second pain (TSSP). Thermal pain threshold, thermal TSSP and aftersensations pain were assessed in 79 healthy individuals with varying degrees of borderline features. TSSP is a proxy measure for central sensitization and refers to the gradual increase in pain to repeated nociceptive stimuli. A regression analysis showed that greater borderline features predicted greater TSSP (β = .22, p = .050, R(2) = .05). Borderline features were unrelated to pain threshold and TSSP decay. A stepwise regression showed greater TSSP in individuals with greater borderline features was accounted for by the negative relationships factor rather than the affect dysregulation factor. The results of mediational analyses showed depression and blunted sympathetic skin conductance responses mediated the positive association between TSSP and borderline features.

  18. Pain in multiple sclerosis: a systematic review of neuroimaging studies.

    PubMed

    Seixas, D; Foley, P; Palace, J; Lima, D; Ramos, I; Tracey, I

    2014-01-01

    While pain in multiple sclerosis (MS) is common, in many cases the precise mechanisms are unclear. Neuroimaging studies could have a valuable role in investigating the aetiology of pain syndromes. The aim of this review was to synthesise and appraise the current literature on neuroimaging studies of pain syndromes in MS. We systematically searched PubMed and Scopus from their inception dates to the 2nd of April 2013. Studies were selected by predefined inclusion and exclusion criteria. Methodological quality was appraised. Descriptive statistical analysis was conducted. We identified 38 studies of variable methodology and quality. All studies but one used conventional structural magnetic resonance imaging, and the majority reported a positive association between location of demyelinating lesions and specific neuropathic pain syndromes. Most investigated headache and facial pain, with more common pain syndromes such as limb pain being relatively understudied. We identified a number of methodological concerns, which along with variable study design and reporting limit our ability to synthesise data. Higher quality studies were however less likely to report positive associations of lesion distribution to pain syndromes. Further high quality hypothesis-driven neuroimaging studies of pain syndromes in MS are required to clarify pain mechanisms, particularly for the commonest pain syndromes.

  19. Pain in multiple sclerosis: A systematic review of neuroimaging studies

    PubMed Central

    Seixas, D.; Foley, P.; Palace, J.; Lima, D.; Ramos, I.; Tracey, I.

    2014-01-01

    Introduction While pain in multiple sclerosis (MS) is common, in many cases the precise mechanisms are unclear. Neuroimaging studies could have a valuable role in investigating the aetiology of pain syndromes. The aim of this review was to synthesise and appraise the current literature on neuroimaging studies of pain syndromes in MS. Methods We systematically searched PubMed and Scopus from their inception dates to the 2nd of April 2013. Studies were selected by predefined inclusion and exclusion criteria. Methodological quality was appraised. Descriptive statistical analysis was conducted. Results We identified 38 studies of variable methodology and quality. All studies but one used conventional structural magnetic resonance imaging, and the majority reported a positive association between location of demyelinating lesions and specific neuropathic pain syndromes. Most investigated headache and facial pain, with more common pain syndromes such as limb pain being relatively understudied. We identified a number of methodological concerns, which along with variable study design and reporting limit our ability to synthesise data. Higher quality studies were however less likely to report positive associations of lesion distribution to pain syndromes. Conclusions Further high quality hypothesis-driven neuroimaging studies of pain syndromes in MS are required to clarify pain mechanisms, particularly for the commonest pain syndromes. PMID:25161898

  20. Effect of adenoviral delivery of prodynorphin gene on experimental inflammatory pain induced by formalin in rats

    PubMed Central

    Chen, Xionggang; Wang, Tingting; Lin, Caizhu; Chen, Baihong

    2014-01-01

    Circumstantial evidences suggest that dynorphins and their common precursor prodynorphin (PDYN) are involved in antinociception and neuroendocrine signaling. DREAM knockout mice had increased levels of PDYN and dynorphin expression, and reduced sensitivity to painful stimuli. However, some data support the notion that the up-regulation of spinal dynorphin expression is a common critical feature in neuropathic pain. It is not clear whether the production of dynorphin A can be increased when more PDYN is present. In this study we investigated the changes in pain behaviors, spinal PDYN mRNA expression and dynorphin A production on formalin-induced pain in rats receiving the pretreatment of adenoviral delivery of PDYN. Our results showed that the adenoviral transfer of PDYN gene was sufficient to reduce pain behaviors resulting from formalin injection, and the antinociceptive effect after receiving the pretreatment of adenoviral delivery of PDYN was mediated at the level of the spinal cord via KOR. PMID:25663984

  1. Antinociceptive effect of botulinum toxin type A on experimental abdominal pain.

    PubMed

    Drinovac, Višnja; Bach-Rojecky, Lidija; Babić, Ana; Lacković, Zdravko

    2014-12-15

    Visceral pain, especially in the abdominal region, represents one of the most common types of pain. Its chronic form is usually very hard to treat by conventional analgesic agents and adjuvants. We investigated the antinociceptive effect of botulinum toxin type A (BTX-A) in male Wistar rats in two models of visceral pain: peritonitis induced by intraperitoneal injection of 1% acetic acid and colitis induced by intracolonic instillation of 0.1% capsaicin. Pain was measured as the number of abdominal writhes. Additionally, referred mechanical sensitivity in the ventral abdominal area was evaluated by von Frey test and the extent of spinal c-Fos expression was immunohistochemically examined. BTX-A significantly reduced the number of abdominal writhes in both models of visceral pain after intrathecal application in a dose of 2 U/kg. In the experimental colitis model, BTX-A (2 U/kg) reduced both referred mechanical allodynia and c-Fos expression in the dorsal horn of the spinal cord (S2/S3 segments). In contrast to intrathecal administration, BTX-A (2 U/kg) administered into the cisterna magna had no effect on pain suggesting that the primary site of its action is a spinal cord.

  2. Effect of Experimental Cutaneous Hand Pain on Corticospinal Excitability and Short Afferent Inhibition

    PubMed Central

    Mercier, Catherine; Gagné, Martin; Reilly, Karen T.; Bouyer, Laurent J.

    2016-01-01

    Sensorimotor integration is altered in people with chronic pain. While there is substantial evidence that pain interferes with neural activity in primary sensory and motor cortices, much less is known about its impact on integrative sensorimotor processes. Here, the short latency afferent inhibition (SAI) paradigm was used to assess sensorimotor integration in the presence and absence of experimental cutaneous heat pain applied to the hand. Ulnar nerve stimulation was combined with transcranial magnetic stimulation to condition motor evoked potentials (MEPs) in the first dorsal interosseous muscle. Four interstimulus intervals (ISI) were tested, based on the latency of the N20 component of the afferent sensory volley (N20−5 ms, N20+2 ms, N20+4 ms, N20+10 ms). In the PAIN condition, MEPs were smaller compared to the NEUTRAL condition (p = 0.005), and were modulated as a function of the ISI (p = 0.012). Post-hoc planned comparisons revealed that MEPs at N20+2 and N20+4 were inhibited compared to unconditioned MEPs. However, the level of inhibition (SAI) was similar in the PAIN and NEUTRAL conditions. This suggests that the interplay between pain and sensorimotor integration is not mediated through direct and rapid pathways as assessed by SAI, but rather might involve higher-order integrative areas. PMID:27690117

  3. Opioid treatment of experimental pain activates nuclear factor-κB

    PubMed Central

    Compton, Peggy; Griffis, Charles; Breen, Elizabeth Crabb; Torrington, Matthew; Sadakane, Ryan; Tefera, Eshetu; Irwin, Michael R.

    2015-01-01

    Objective To determine the independent and combined effects of pain and opioids on the activation of an early marker of inflammation, nuclear factor-κB (NF-κB). Design NF-κB activation was compared within-subjects following four randomly ordered experimental sessions of opioid-only (intravenous fentanyl 1 μg/kg), pain-only (cold-pressor), opioid + pain, and a resting condition. Setting University General Clinical Research Center. Participants Twenty-one (11 female) healthy controls. Interventions Following exposure to treatment (fentanyl administration and/or cold-pressor pain), blood samples for NF-kB analysis were obtained. Main outcome measures Intracellular levels of activated NF-κB, in unstimulated and stimulated peripheral blood mononuclear cells at 15 and 30 minutes. Results Neither pain nor opioid administration alone effected NF-κB levels in cell populations; however, the combination of treatments induced significant increases of NF-κB in stimulated peripheral blood mononuclear cell, lymphocytes, and monocytes. Conclusions The combination of acute pain with opioids, as occurs in clinical situations, activates a key transcription factor involved in proinflammatory responses. PMID:25901477

  4. Effect of Experimental Cutaneous Hand Pain on Corticospinal Excitability and Short Afferent Inhibition.

    PubMed

    Mercier, Catherine; Gagné, Martin; Reilly, Karen T; Bouyer, Laurent J

    2016-09-29

    Sensorimotor integration is altered in people with chronic pain. While there is substantial evidence that pain interferes with neural activity in primary sensory and motor cortices, much less is known about its impact on integrative sensorimotor processes. Here, the short latency afferent inhibition (SAI) paradigm was used to assess sensorimotor integration in the presence and absence of experimental cutaneous heat pain applied to the hand. Ulnar nerve stimulation was combined with transcranial magnetic stimulation to condition motor evoked potentials (MEPs) in the first dorsal interosseous muscle. Four interstimulus intervals (ISI) were tested, based on the latency of the N20 component of the afferent sensory volley (N20-5 ms, N20+2 ms, N20+4 ms, N20+10 ms). In the PAIN condition, MEPs were smaller compared to the NEUTRAL condition (p = 0.005), and were modulated as a function of the ISI (p = 0.012). Post-hoc planned comparisons revealed that MEPs at N20+2 and N20+4 were inhibited compared to unconditioned MEPs. However, the level of inhibition (SAI) was similar in the PAIN and NEUTRAL conditions. This suggests that the interplay between pain and sensorimotor integration is not mediated through direct and rapid pathways as assessed by SAI, but rather might involve higher-order integrative areas.

  5. Experimental orofacial pain and sensory deprivation lead to perceptual distortion of the face in healthy volunteers.

    PubMed

    Dagsdóttir, Lilja Kristín; Skyt, Ina; Vase, Lene; Baad-Hansen, Lene; Castrillon, Eduardo; Svensson, Peter

    2015-09-01

    Patients suffering from persistent orofacial pain may sporadically report that the painful area feels "swollen" or "differently," a phenomenon that may be conceptualized as a perceptual distortion because there are no clinical signs of swelling present. Our aim was to investigate whether standardized experimental pain and sensory deprivation of specific orofacial test sites would lead to changes in the size perception of these face areas. Twenty-four healthy participants received either 0.2 mL hypertonic saline (HS) or local anesthetics (LA) into six regions (buccal, mental, lingual, masseter muscle, infraorbital and auriculotemporal nerve regions). Participants estimated the perceived size changes in percentage (0 % = no change, -100 % = half the size or +100 % = double the size), and somatosensory function was checked with tactile stimuli. The pain intensity was rated on a 0-10 Verbal Numerical Rating Scale (VNRS), and sets of psychological questionnaires were completed. HS and LA were associated with significant self-reported perceptual distortions as indicated by consistent increases in perceived size of the adjacent face areas (P ≤ 0.050). Perceptual distortion was most pronounced in the buccal region, and the smallest increase was observed in the auriculotemporal region. HS was associated with moderate levels of pain VNRS = 7.3 ± 0.6. Weak correlations were found between HS-evoked perceptual distortion and level of dissociation in two regions (P < 0.050). Experimental pain and transient sensory deprivation evoked perceptual distortions in all face regions and overall demonstrated the importance of afferent inputs for the perception of the face. We propose that perceptual distortion may be an important phenomenon to consider in persistent orofacial pain conditions.

  6. [Control of postoperative pain in children undergoing hypospadias surgery: quasi-experimental controlled trial].

    PubMed

    Festini, Filippo; Dini, Donata; Neri, Cinzia; Neri, Stella

    2008-01-01

    Hypospadias is one of the most common congenital anomalies occurring in approximately (1/300) male births. If it is not surgically corrected the consequences may negatively impact on quality of life in adolescents. The surgery is very invasive and the post-operative phase very painful. To improve the control of post-operative pain, continuous analgesia via epidural catheter was implemented. To compare the effectiveness in controlling pain of two different regimens: continuous epidural catheter infusion vs oral and rectal non-steroidal pain-killers. Comparative study on children undergoing hypospadias surgery. Group A (catheter) was treated with continuous postoperative analgesia via epidural catheter and Group B (scheduled times) with rectal and oral analgesics at scheduled times and on demand, after caudal block. In both groups nurses measured pain with VAS and FLACC scales (score from 0 to 10) for 72 hours after surgery. 41 children were studied (average age 64.1 months, SD 47.3), with 332 post-operative pain recordings (Group A n = 161, Group B n = 171). Mean pain score of Group A was 0.13 (SD 0.3) and 0.45 (SD 0.8) in group B, p = 0.006. The median duration of the epidural catheter was 65 hours, mean 51.8 hours (SD 24.3). During the 1st post-operative medication, the mean pain score in Group A was 1.2 (SD 1.4), and 3.2 (SD 1.8) in group B, p = 0.003. In group A the number of pain scores indicating pain (> 0) where 3.1% while in group B were 10.5%, p = 0.0007. In children undergoing hypospadias surgery, post-operative analgesia with continuous epidural catheter infusion seems to offer a better analgesic coverage than the traditional oral/rectal analgesic treatment at scheduled times and on demand.

  7. EXPERIMENTAL STUDIES ON INFLAMMATION

    PubMed Central

    Wolf, Elizabeth Pauline

    1921-01-01

    1. Wright's method for the study of chemotaxis of leucocytes in vitro, slightly modified, has been found to be most satisfactory in the estimation of the degree of chemotaxis of various substances, because it is possible to make an exact quantitative determination of the leucocytes that have migrated from the blood clot and adhere to the surfaces containing the tested substance. 2. The calcium ion is the only inorganic ion per se which is found to be positively chemotactic under the conditions of these experiments. It is markedly chemotactic in all concentrations and in all combinations, except the citrate. Here the negative chemotaxis of the citrate ion neutralizes the positive chemotaxis of the calcium ion, and neutrality of chemotactic effect results. 3. The sodium and magnesium ions themselves are neutral. Magnesium and sodium salts are dependent upon the negative ion with which the magnesium or sodium is combined for such positive or negative chemotaxis as is exhibited. All the phosphates of sodium, whether tri-, di-, or monobasic salts, are markedly positively chemotactic, and when combined with other reagents which are themselves neutral or negatively chemotactic, produce marked positive chemotaxis. The blood of a person who has taken phosphates either by mouth or intravenously shows a great increase in chemotaxis with sodium phosphate, with calcium chloride, and even with sodium chloride which is ordinarily neutral. 4. All potassium salts are negatively chemotactic. 5. Many substances act synergistically as regards chemotaxis; e.g., when strontium and magnesium salts are mixed there is a marked increase in chemotaxis. Sodium phosphate acts synergistically with calcium chloride. 6. Mercury salts fix the leucocytes in this method so that their influence on chemotaxis cannot be determined. 7. Morphine and morphine salts are positively chemotactic; this is contrary to the results obtained by others with different methods. 8. Substances which produce a very

  8. Computerized assessment of pain drawing area: A pilot study

    PubMed Central

    Wenngren, Anna; Stålnacke, Britt-Marie

    2009-01-01

    Aim: To investigate if pain area in patients with chronic pain could be measured by a computerized assessment on previously marked pain drawings on paper figures and to analyze the further application of the method. Methods: Seventy-two patients (54 women and 18 men) who were admitted to Umeå University Hospital during 2003 for assessment of chronic pain answered a set of questionnaires (pain intensity on the visual analog scale [VAS], disability on the Disability Rating Index [DRI], life satisfaction on the LiSat-11) and filled in pain drawings on paper figures of the human body. The pain drawings were later analyzed by using computerized assessment. Results: Women marked a greater pain area than men, but the difference was not significant (p =0.433). No significant difference was shown for the previous seven days between men and women on the VAS (p =0.914), DRI (p =0.493), or LiSat-11 (p =0.124). A statistically significant correlation was found between pain area and VAS for the previous seven days (r =0.250; p =0.046). Pain area was statistically significantly correlated to the DRI (r =0.336; p =0.014) and close to negatively correlated to the LiSat-11 (r =0.687; p =0.057). Conclusion: This pilot study shows that pain drawing area could be measured by a computerized assessment of pain drawings. The method points to the possibility of relating pain area with other instruments. In the present study, an association between the patients’ pain drawing area and pain intensity and between pain area and level of activity was shown. PMID:19721724

  9. Burn patients' experience of pain management: a qualitative study.

    PubMed

    Yuxiang, Li; Lingjun, Zhou; Lu, Tang; Mengjie, Liu; Xing, Ming; Fengping, Shen; Jing, Cui; Xianli, Meng; Jijun, Zhao

    2012-03-01

    Pain is a major problem after burns and researchers continue to report that pain from burns remains undertreated. The inadequate pain control results in adverse sequalae physically and psychologically in the burn victims. A better understanding of a burn patient's experience is important in identifying the factors responsible for undertreated pain and establishing effective pain management guidelines or recommendation in the practice of pain relief for burn injuries. This study sought to explore and describe the experience that patients have about pain related to burn-injury during hospitalization. Semi-structured interviews were conducted on eight patients with moderate to severe pain from burn injuries recruited from a Burn Centre in Northwest China. Data was collected by in-depth interviews and qualitative description after full transcription of each interview. Analysis involved the identification of themes and the development of a taxonomy of patients' experience of burn pain and its management. Three themes were indentified: (1) patients' experience of pain control, (2) patients' perception on burn pain management, and (3) patients' expectation of burn pain management. Findings from this study suggested that patients experience uncontrolled pain both physically and psychologically which may serve as an alert for awareness of health professionals to recognize and establish a multidisciplinary pain management team for burn victims, including surgeons, critical care specialists, anesthesiologists, nurses, psychologists, and social workers to accomplish safe and effective strategies for pain control to reach an optimal level of pain management in burn patients. It also provides insights and suggestions for future research directions to address this significant clinical problem.

  10. A prospective study on postoperative pain after cataract surgery

    PubMed Central

    Porela-Tiihonen, Susanna; Kaarniranta, Kai; Kokki, Merja; Purhonen, Sinikka; Kokki, Hannu

    2013-01-01

    Purpose To evaluate postoperative pain and early recovery in cataract patients. Patients and methods A total of 201 patients who underwent elective first eye cataract extraction surgery were enrolled, and 196 were included in the final analysis. The study design was a single-center, prospective, follow-up study in a tertiary hospital in eastern Finland. Postoperative pain was evaluated with the Brief Pain Inventory at four time points: at baseline, and at 24 hours, 1 week, and 6 weeks postsurgery. Results Postoperative pain was relatively common during the first hours after surgery, as it was reported by 67 (34%) patients. After hospital discharge, the prevalence decreased; at 24 hours, 1 week, and 6 weeks, 18 (10%), 15 (9%) and 12 (7%) patients reported having ocular pain, respectively. Most patients with eye pain reported significant pain, with a score of ≥4 on a pain scale of 0–10, but few had taken analgesics for eye pain. Those who had used analgesics rated the analgesic efficacy of paracetamol and ibuprofen as good or excellent. Other ocular irritation symptoms were common after surgery; as a new postoperative symptom, foreign-body sensation was reported by 40 patients (22%), light sensitivity by 29 (16%), burning by 15 (8%), and itching by 15 (8%). Conclusion Moderate or severe postoperative pain was relatively common after cataract surgery. Thus, all patients undergoing cataract surgery should be provided appropriate counseling on pain and pain management after surgery. PMID:23885165

  11. The predictive value of attentional bias towards pain-related information in chronic pain patients: a diary study.

    PubMed

    Van Ryckeghem, Dimitri M L; Crombez, Geert; Goubert, Liesbet; De Houwer, Jan; Onraedt, Thomas; Van Damme, Stefaan

    2013-03-01

    Theoretical accounts of chronic pain hypothesize that attentional bias towards pain-related information is a maintaining or exacerbating factor, fuelling further pain, disability, and distress. However, empirical research testing this idea is currently lacking. In the present study, we investigated whether attentional bias towards pain-related information predicts daily pain-related outcomes in a sample of chronic pain patients (n=69; M(age)=49.64 years; 46 females). During an initial laboratory session, attentional bias to pain-related information was assessed using a modified spatial cueing task. In advance, patients completed a number of self-report measures assessing current pain intensity, current disability, and pain duration. Subsequently, daily pain outcomes (self-reported pain severity, disability, avoidance behaviour, and distractibility) were measured for 2 weeks by means of an electronic diary. Results indicated that, although an attentional bias towards pain-related information was associated with the current level of disability and pain severity, it had no additional value above control variables in predicting daily pain severity, avoidance, distractibility, and disability. Attentional bias towards pain-related information did, however, moderate the relationship between daily pain severity and both daily disability and distractibility, indicating that, particularly in those patients with a strong attentional bias, increases in pain were associated with increased disability and distractibility. The use of interventions that diminish attentional bias may therefore be helpful to reduce daily disability and the level of distraction from current tasks despite the presence of pain in chronic pain patients.

  12. Acute experimental endotoxemia induces visceral hypersensitivity and altered pain evaluation in healthy humans.

    PubMed

    Benson, Sven; Kattoor, Joswin; Wegner, Alexander; Hammes, Florian; Reidick, Daniel; Grigoleit, Jan-Sebastian; Engler, Harald; Oberbeck, Reiner; Schedlowski, Manfred; Elsenbruch, Sigrid

    2012-04-01

    Growing evidence suggests that systemic immune activation plays a role in the pathophysiology of pain in functional bowel disorders. By implementing a randomized crossover study with an injection of endotoxin or saline, we aimed to test the hypothesis that endotoxin-induced systemic inflammation increases visceral pain sensitivity in humans. Eleven healthy men (mean ± standard error of the mean age 26.6 ± 1.1 years) received an intravenous injection of either lipopolysaccharide (LPS; 0.4 ng/kg) or saline on 2 otherwise identical study days. Blood samples were collected 15 min before and 1, 2, 3, 4, and 6h after injection to characterize changes in immune parameters including proinflammatory cytokines. Rectal sensory and pain thresholds and subjective pain ratings were assessed with barostat rectal distensions 2h after injection. LPS administration induced an acute inflammatory response indicated by transient increases in tumor necrosis factor alpha, interleukin 6, and body temperature (all P<.001). The LPS-induced immune activation increased sensitivity to rectal distensions as reflected by significantly decreased visceral sensory and pain thresholds (both P<.05) compared to saline control. Visceral stimuli were rated as more unpleasant (P<.05) and inducing increased urge to defecate (P<.01). Pain thresholds correlated with interleukin 6 at +1h (r=0.60, P<.05) and +3h (r=0.67, P<.05) within the LPS condition. This report is novel in that it demonstrates that a transient systemic immune activation results in decreased visceral sensory and pain thresholds and altered subjective pain ratings. Our results support the relevance of inflammatory processes in the pathophysiology of visceral hyperalgesia and underscore the need for studies to further elucidate immune-to-brain communication pathways in gastrointestinal disorders. Copyright © 2011 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

  13. Pain perception and hypnosis: findings from recent functional neuroimaging studies.

    PubMed

    Del Casale, Antonio; Ferracuti, Stefano; Rapinesi, Chiara; Serata, Daniele; Caltagirone, Saverio Simone; Savoja, Valeria; Piacentino, Daria; Callovini, Gemma; Manfredi, Giovanni; Sani, Gabriele; Kotzalidis, Georgios D; Girardi, Paolo

    2015-01-01

    Hypnosis modulates pain perception and tolerance by affecting cortical and subcortical activity in brain regions involved in these processes. By reviewing functional neuroimaging studies focusing on pain perception under hypnosis, the authors aimed to identify brain activation-deactivation patterns occurring in hypnosis-modulated pain conditions. Different changes in brain functionality occurred throughout all components of the pain network and other brain areas. The anterior cingulate cortex appears to be central in modulating pain circuitry activity under hypnosis. Most studies also showed that the neural functions of the prefrontal, insular, and somatosensory cortices are consistently modified during hypnosis-modulated pain conditions. Functional neuroimaging studies support the clinical use of hypnosis in the management of pain conditions.

  14. Dose-specific effects of transcutaneous electrical nerve stimulation (TENS) on experimental pain: a systematic review.

    PubMed

    Claydon, Leica S; Chesterton, Linda S; Barlas, Panos; Sim, Julius

    2011-09-01

    To determine the hypoalgesic effects of transcutaneous electrical nerve stimulation (TENS) parameter combinations on experimental models in healthy humans. Searches were performed using the electronic databases Ovid MEDLINE, CINAHL, AMED, and Web of Science (from inception to December 2009). Manual searches of journals and reference lists of retrieved trials were also performed. Randomized controlled trials (RCTs) were included in the review if they compared the hypoalgesic effect of TENS relative with placebo and control, using an experimental pain model in healthy human participants. Two reviewers independently selected the trials, assessed their methodologic quality and extracted data. Forty-three RCTs were eligible for inclusion. A best evidence synthesis revealed: Overall "conflicting" (inconsistent findings in multiple RCTs) evidence of TENS efficacy on experimental pain irrespective of TENS parameters used. Overall intense TENS has "moderate" evidence of efficacy (1 high-quality and 2 low-quality trials). Conventional TENS has overall conflicting evidence of efficacy, this is derived from "strong" evidence of efficacy (generally consistent findings in multiple high-quality RCTs) on pressure pain but strong evidence of inefficacy on other pain models. "Limited" evidence (positive findings from 1 RCT) of hypoalgesia exists for some novel parameters. Low-intensity, low-frequency, local TENS has strong evidence of inefficacy. Inappropriate TENS (using "barely perceptible" intensities) has moderate evidence of inefficacy. The level of hypoalgesic efficacy of TENS is clearly dependent on TENS parameter combination selection (defined in terms of intensity, frequency, and stimulation site) and experimental pain model. Future clinical RCTs may consider these TENS dose responses.

  15. Pelvic pain after childbirth: a longitudinal population study.

    PubMed

    Bjelland, Elisabeth Krefting; Owe, Katrine Mari; Pingel, Ronnie; Kristiansson, Per; Vangen, Siri; Eberhard-Gran, Malin

    2016-03-01

    In this longitudinal population study, the aims were to study associations of mode of delivery with new onset of pelvic pain and changes in pelvic pain scores up to 7 to 18 months after childbirth. We included 20,248 participants enrolled in the Norwegian Mother and Child Cohort Study (1999-2008) without preexisting pelvic pain in pregnancy. Data were obtained by 4 self-administered questionnaires and linked to the Medical Birth Registry of Norway. A total of 4.5% of the women reported new onset of pelvic pain 0 to 3 months postpartum. Compared to unassisted vaginal delivery, operative vaginal delivery was associated with increased odds of pelvic pain (adjusted odds ratio [OR]: 1.30; 95% confidence interval [CI]: 1.06-1.59). Planned and emergency cesarean deliveries were associated with reduced odds of pelvic pain (adjusted OR: 0.48; 95% CI: 0.31-0.74 and adjusted OR: 0.65; 95% CI: 0.49-0.87, respectively). Planned cesarean delivery, young maternal age, and low Symptom Checklist-8 scores were associated with low pelvic pain scores after childbirth. A history of pain was the only factor associated with increased pelvic pain scores over time (P = 0.047). We conclude that new onset of pelvic pain after childbirth was not commonly reported, particularly following cesarean delivery. Overall, pelvic pain scores were rather low at all time points and women with a history of pain reported increased pelvic pain scores over time. Hence, clinicians should follow up women with pelvic pain after a difficult childbirth experience, particularly if they have a history of pain.

  16. Revising the negative meaning of chronic pain - A phenomenological study.

    PubMed

    Ojala, Tapio; Häkkinen, Arja; Karppinen, Jaro; Sipilä, Kirsi; Suutama, Timo; Piirainen, Arja

    2015-06-01

    Chronic pain may disable the body, depress the mind and ruin the quality of life. The aim of this study was to use the participants' personal experiences to explore the meaning of the experience of chronic pain and to find successful ways to manage chronic pain. Thirty-four participants with chronic pain were interviewed. The transcribed interviews were analysed using Giorgi's phenomenological method consisting of four phases: (1) reading the transcriptions several times, (2) discriminating meaning units, (3) collecting meaning units into groups and (4) the synthesis. The participants stated that the key to managing chronic pain was to reconsider the individual meaning of the experience of pain. As a result of the interviews, seven subthemes were found based on the 'Negativity of chronic pain', namely, 'State of reflection', 'Reconsidering values', 'Acceptance of pain', 'Support network', 'Altered self', 'Joys in life' and 'Pain dissociation'. Pain is an aversive sensation, which leads to the conclusion that the meaning of the experience is also negative, but it can be reversed. In clinical practice, the focus should be on revising the subjective meaning of pain in order to manage pain and to restore positivity in personal life. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  17. A preliminary study on how hypohydration affects pain perception.

    PubMed

    Bear, Tracey; Philipp, Michael; Hill, Stephen; Mündel, Toby

    2016-05-01

    Chronic pain is a prevalent health issue with one in five people suffering from some form of chronic pain, with loss of productivity and medical costs of chronic pain considerable. However, the treatment of pain can be difficult, as pain perception is complex and can be affected by factors other than tissue damage. This study investigated the effect of hypohydration (mild, voluntary dehydration from ∼24 h of limiting fluid intake, mimicking someone drinking less than usual) on a person's pain perception. Seventeen healthy males (age 27 ± 5 years) visited the laboratory on three occasions, once as a familiarization and then twice again while either euhydrated (urine specific gravity: 1.008 ± 0.005) or hypohydrated (urine specific gravity: 1.024 ± 0.003, and -1.4 ± 0.9% body mass). Each visit, they performed a cold pressor test, where their feet were placed in cold water (0-3 °C) for a maximum of 4 min. Measures of hydration status, pain sensitivity, pain threshold, and catastrophization were taken. We found that hypohydration predicted increased pain sensitivity (β = 0.43), trait pain catastrophizing, and baseline pain sensitivity (β = 0.37 and 0.47, respectively). These results are consistent with previous research, and suggest that a person's hydration status may be an important factor in their perception of acute pain. © 2016 Society for Psychophysiological Research.

  18. Relationship between Temporomandibular Disorders, Widespread Palpation Tenderness and Multiple Pain Conditions: A Case - Control Study

    PubMed Central

    Chen, Hong; Slade, Gary; Lim, Pei Feng; Miller, Vanessa; Maixner, William; Diatchenko, Luda

    2012-01-01

    The multiple bodily pain conditions in temporomandibular disorders (TMD) have been associated with generalized alterations in pain processing. The purpose of this study was to examine the relationship between the presence of widespread body palpation tenderness (WPT) and the likelihood of multiple comorbid pain conditions in TMD patients and controls. This case-control study was conducted in 76 TMD subjects with WPT, 83 TMD subjects without WPT, and 181 non-TMD matched control subjects. The study population was also characterized for clinical pain, experimental pain sensitivity, and related psychological phenotypes. Results showed that (1) TMD subjects reported an average of 1.7 comorbid pain conditions compared to 0.3 reported by the control subjects (p<0.001); (2) Compared to control subjects, the odds ratio (OR) for multiple comorbid pain conditions is higher for TMD subjects with WPT [OR 8.4 (95% CI 3.1–22.8) for TMD with WPT versus OR 3.3 (95% CI 1.3–8.4) for TMD without WPT]; (3) TMD subjects with WPT presented with reduced pressure pain thresholds (PPTs) in both cranial and extra-cranial regions compared to TMD subjects without WPT; and (4) TMD subjects with WPT reported increased somatic symptoms. These findings suggest that pain assessment outside of the orofacial region may prove valuable for the classification, diagnosis, and management of TMD patients. PMID:23031401

  19. Jaw-motor effects of experimental jaw-muscle pain and stress in patients with deep bite and matched control subjects.

    PubMed

    Sonnesen, Liselotte; Svensson, Peter

    2013-10-01

    The effect of experimental jaw-muscle pain and stress on masticatory muscle activity in TMD-patients has been discussed. Furthermore, associations between TMD and deep bite patients have been studied. Accordingly in the present study, comparison of EMG responses at rest, maximal clenching, during evoked pain and stress between deep bite patients and controls was investigated. In 30 deep bite patients and in 30 sex-/age-matched controls with neutral occlusion EMG activity was recorded bilaterally from masseter and anterior temporalis muscles before and during evoked pain and before and during a stress task. Evoked pain was induced by injections of glutamate into the masseter (local pain) and brachioradialis (remote pain) muscles and resting EMG activity was recorded before and after 1, 2, 3, 4, 5 and 10min. A precision task was used to simulate a stressful condition and EMG activity was recorded twice during the task. Maximal EMG activity was recorded during maximal clenching. Resting and maximal EMG activity were significantly different between groups and age with no gender differences. EMG activity during local pain and during the precision task were significantly different between groups, gender, age and time, whereas no time effect was found for the EMG activity during remote pain. Patients with deep bite have significantly different jaw motor responses to painful stimulation of the trigeminal region and manual precision tasks suggesting a differential integration of both somatosensory and behavioural stimuli. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. Pain in Alzheimer's disease: A study of behavior and neural correlates

    NASA Astrophysics Data System (ADS)

    Beach, Paul Anthony

    Alzheimer's disease (AD) is a devastating neurodegenerative disease characterized by insidious and progressive impairment of cognition, emotion, and memory. Though pain in patients with AD is a major medical concern it is under diagnosed and under treated in patients, compared to cognitively healthy elderly. Further complicating matters, subjective self-report of pain by becomes increasingly compromised with disease progression; this often leaves clinicians and caregivers no choice but to rely on discerning pain from behavior alone. Patients also report pain at a lower frequency and intensity than healthy seniors (HS). These findings, coupled with recognition that AD pathology affects many pain processing brain regions, have prompted examination of whether AD alters pain perception. While there is evidence that AD actually predisposes heightened perception of pain, several issues remain: experimental work is limited to a handful of studies, whose results have been inconsistent; few examinations of pain in AD have included patients with advanced disease; the neural mechanism underlying altered pain in AD is not clear. I addressed these gaps in the literature by examining subjective, behavioral, and autonomic pain responses in 33 HS and 38 patients with varying severities of AD. A subset of these subjects (24 HS and 20 AD) were scanned, using fMRI. I then determined how the functional connectivity of various resting-state networks (RSNs) were associated with measured pain responses. I found that AD patients rated low-level stimuli as more painful than HS. Also, patients, regardless of severity, showed greater degrees of pain behaviors than HS - both with respect to global behaviors as measured by a clinical pain scale and facial responses as measured by an experimental tool. In contrast, autonomic responses were blunted with advancing AD. Altered pain responses in AD were associated with altered function of RSNs involved in attention and internal mentation, affect

  1. Pain experiences of patients with musculoskeletal pain + central sensitization: A comparative Group Delphi Study

    PubMed Central

    Schäfer, Axel Georg Meender; Joos, Leonie Johanna; Roggemann, Katharina; Waldvogel-Röcker, Kerstin; Pfingsten, Michael; Petzke, Frank

    2017-01-01

    Objectives Central sensitization (CS) is regarded as an important contributing factor for chronification of musculoskeletal pain (MSP). It is crucial to identify CS, as targeted multimodal treatment may be indicated. The primary objective of this study was therefore to explore pain experience of individuals with MSP+CS in order to gain a better understanding of symptoms in relation to CS from a patient perspective. The secondary objective was to investigate whether pain experiences of patients with MSP+CS differ from those of individuals with neuropathic pain (NP). Methods We conducted a comparative Group Delphi Study including patients with MSP+CS and neuropathic pain (NP). 13 guiding questions were used to gather information about sensory discriminatory, affective and associated bodily, mental and emotional phenomena related to the pain experience of patients. Descriptions were categorized using qualitative content analysis. Additionally, patients completed several pain related questionnaires. Results Nine participants with MSP+CS and nine participants with NP participated. The Delphi procedure revealed three main themes: psycho-emotional factors, bodily factors and environmental factors. Descriptions of patients with MSP+CS showed a complex picture, psycho-emotional factors seem to have a considerable impact on pain provocation, aggravation and relief. Impairments associated with mental ability and psyche affected many aspects of daily life. In contrast, descriptions of patients with NP revealed a rather mechanistic and bodily oriented pain experience. Discussion Patients with MSP+CS reported distinct features in relation to their pain that were not captured with current questionnaires. Insight in patient’s pain experience may help to choose and develop appropriate diagnostic instruments. PMID:28796805

  2. Pain after shoulder arthroscopy: a prospective study on 231 cases.

    PubMed

    Stiglitz, Y; Gosselin, O; Sedaghatian, J; Sirveaux, F; Molé, D

    2011-05-01

    Shoulder arthroscopy is reputed to be painful, but progression of postoperative pain after this type of surgery has never been described and analyzed. This study had a triple objective: the description, search for risk factors, and analysis of the long-term impact of postoperative pain. This continuous prospective series includes 231 patients who underwent arthroscopic shoulder surgery. Pain was evaluated from D-1 to D3, then at D7, D30, and 1 year. Three pain criteria were noted: visual analog scale (VAS), morphine intake, and satisfaction with pain management. Surgery was performed under general anesthesia and/or interscalene block. A local anesthetic complement was administered in one of four modes: single subacromial injection, subacromial catheter, intra-articular catheter, or no complement. The VAS values remained less than 4 out of 10 during the entire study. Immediate postoperative pain was less than preoperative pain. It was followed by a pain bounce on D1 and D2 and did not return to a level significantly lower than its preoperative value until D30. Rotator cuff repair is the most painful surgery in the first postoperative days. The main risk factor for pain is a work related accident or occupational disease, associated with higher VAS values from D1 to 1 year and greater morphine intake. There was no correlation between immediate postoperative and 1-year VAS values. Pain after shoulder arthroscopy is relatively low and the efficacy of the intervention is long-lasting in terms of pain symptom. A pain bounce appears on D1, which must be taken into account, notably in the context of outpatient surgery. The use of local anesthesia is therefore advantageous. Despite the efficacy of postoperative pain relief protocols, their effect on longer term perspective was not demonstrated. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

  3. Experimental studies: randomized clinical trials.

    PubMed

    Gjorgov, A N

    1998-01-01

    There are two major approaches to medical investigations: observational studies and experimental trials. The classical application of the experimental design to studies of human populations is the randomized clinical trial of the efficacy of a new drug or treatment. A further application of the experimental studies is to the testing of hypotheses about the etiology of a disease, already tested and corroborated from various forms of observational studies. Ethical considerations and requirements for consent of the experimental subjects are of primary concern in the clinical trials, and those concerns set the first and final limits for implementing a trial. General moral principles in research with human and animal beings, defined by the "Nuremberg Code," deal with strict criteria for approval, endorsement and evaluation of a clinical trial.

  4. Predictors of opioid efficacy in patients with chronic pain: A prospective multicenter observational cohort study

    PubMed Central

    Olesen, Anne E.; Gram, Mikkel; Jonsson, Torsten; Kamp-Jensen, Michael; Andresen, Trine; Nielsen, Christian; Pozlep, Gorazd; Pfeiffer-Jensen, Mogens; Morlion, Bart; Drewes, Asbjørn M.

    2017-01-01

    Opioids are increasingly used for treatment of chronic pain. However, they are only effective in a subset of patients and have multiple side effects. Thus, studies using biomarkers for response are highly warranted. The current study prospectively examined 63 opioid-naïve patients initiating opioid use for diverse types of chronic pain at five European centers. Quantitative sensory testing, electroencephalography (EEG) recordings, and assessment of pain catastrophizing were performed prior to treatment. The co-primary outcomes were change from baseline in ratings of chronic pain and quality of life after 14 days of opioid treatment. Secondary outcomes included patient’s global impression of clinical change and side effects. Logistic regression models adjusted for age and sex were used to identify biomarkers predictive for successful treatment, defined as at least a 30% reduction in average pain intensity or an improvement in quality of life of at least 10 scale points. Fifty-nine patients (94%) completed the study. The mean age was 55 ± 16 years and 69% were females. Pain reduction was predicted by cold pain intensity (OR: 0.69; P = 0.01), pain catastrophizing (OR: 0.82; P = 0.03), relative delta (OR: 0.76; P = 0.03) and beta EEG activity (OR: 1.18; P = 0.04) induced by experimental cold pain. None of the study variables were related to improvement in quality of life. For the first time, individual pain processing characteristics have been linked to opioid response in a mixed chronic pain population. This has the potential to personalize treatment of chronic pain and restrict opioid use to patients with high likelihood for response. PMID:28158269

  5. Computed tomographic studies of the painful abdomen

    SciTech Connect

    Benson, M.; Bree, R.L.; Schwab, R.E.; Ouimette, M.

    1985-05-01

    Abdominal CT scans were reviewed in a series of 53 patients who had abdominal pain without objective physical, radiographic, or laboratory abnormalities. Forty patients presented with abdominal pain alone, while the remaining patients had abdominal pain associated with nausea, vomiting or mild weight loss. Abdominal CT scans in all patients were interpreted as normal. One patient had a pancreatic carcinoma discovered at surgery one month after the CT scan was obtained. The patients were followed up for 6 to 12 months to confirm absence of significant disease. Our analysis suggests a very low yield from abdominal CT in patients with abdominal pain and no other objective findings.

  6. Demographic Predictors of Pain Sensitivity: Results From the OPPERA Study.

    PubMed

    Ostrom, Cara; Bair, Eric; Maixner, William; Dubner, Ronald; Fillingim, Roger B; Ohrbach, Richard; Slade, Gary D; Greenspan, Joel D

    2017-03-01

    The demographic factors of sex, age, and race/ethnicity are well recognized as relevant to pain sensitivity and clinical pain expression. Of these, sex differences have been the most frequently studied, and most of the literature describes greater pain sensitivity for women. The other 2 factors have been less frequently evaluated, and current literature is not definitive. Taking advantage of the large Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) study cohort, we evaluated the association of sex, age, and self-reported race with 34 measures of pressure, mechanical, and thermal pain sensitivity encompassing threshold and suprathreshold perception. Women were significantly more pain-sensitive than men for 29 of 34 measures. Age effects were small, and only significant for 7 of 34 measures, however, the age range was limited (18-44 years of age). Race/ethnicity differences varied across groups and pain assessment type. Non-Hispanic white individuals were less pain-sensitive than African-American (for 21 of 34 measures), Hispanic (19 of 34), and Asian (6 of 34) individuals. No pain threshold measure showed significant racial differences, whereas several suprathreshold pain measures did. This suggests that racial differences are not related to tissue characteristics or inherent nociceptor sensitivity. Rather, the differences observed for suprathreshold pain ratings or tolerance are more likely related to differences in central nociceptive processing, including modulation imposed by cognitive, psychological, and/or affective factors.

  7. Pain anticipatory phenomena in patients with central poststroke pain: a magnetoencephalography study.

    PubMed

    Gopalakrishnan, Raghavan; Burgess, Richard C; Lempka, Scott F; Gale, John T; Floden, Darlene P; Machado, Andre G

    2016-09-01

    Central poststroke pain (CPSP) is characterized by hemianesthesia associated with unrelenting chronic pain. The final pain experience stems from interactions between sensory, affective, and cognitive components of chronic pain. Hence, managing CPSP will require integrated approaches aimed not only at the sensory but also the affective-cognitive spheres. A better understanding of the brain's processing of pain anticipation is critical for the development of novel therapeutic approaches that target affective-cognitive networks and alleviate pain-related disability. We used magnetoencephalography (MEG) to characterize the neural substrates of pain anticipation in patients suffering from intractable CPSP. Simple visual cues evoked anticipation while patients awaited impending painful (PS), nonpainful (NPS), or no stimulus (NOS) to their nonaffected and affected extremities. MEG responses were studied at gradiometer level using event-related fields analysis and time-frequency oscillatory analysis upon source localization. On the nonaffected side, significantly greater responses were recorded during PS. PS (vs. NPS and NOS) exhibited significant parietal and frontal cortical activations in the beta and gamma bands, respectively, whereas NPS (vs. NOS) displayed greater activation in the orbitofrontal cortex. On the affected extremity, PS (vs. NPS) did not show significantly greater responses. These data suggest that anticipatory phenomena can modulate neural activity when painful stimuli are applied to the nonaffected extremity but not the affected extremity in CPSP patients. This dichotomy may stem from the chronic effects of pain on neural networks leading to habituation or saturation. Future clinically effective therapies will likely be associated with partial normalization of the neurophysiological correlates of pain anticipation.

  8. Continuous neurophatic orofacial pain: A retrospective study of 23 cases

    PubMed Central

    Sotorra-Figuerola, Dídac; Sánchez-Torres, Alba; Valmaseda-Castellón, Eduard

    2016-01-01

    Background To determine the clinical characteristics of Continuous Neuropathic Orofacial Pain in patients that suffer Persistent Idiopathic Facial Pain (PIFP), Painful Post-Traumatic Trigeminal Neuropathy (PPTTN) or Burning Mouth Syndrome (BMS) and to describe their treatment. Material and Methods A retrospective observational study was made, reviewing the clinical history of the patients diagnosed with Continuous Neuropathic Orofacial Pain between 2004 and 2011 at the Orofacial Pain Unit of the Master of Oral Surgery and Implantology of the University of Barcelona and at the Orofacial Pain Unit of the Teknon Medical Center of Barcelona. Results The average age of the patients with Continuous Neuropathic Orofacial Pain was 54.5, with a clear female predominance (86.9%, n=20). Of all patients, 60.9% (n=14) were suffering a PIFP, 21.7% (n=5) had a BMS and 17.4% (n=4) were presenting a PPTTN. The pain quality described by the patients with Continuous Neuropathic Orofacial Pain was oppressive (43.47%, n=10), widely represented by patients with PIFP, and burning (39.13%, n=9) being the only quality that described patients with BMS. The treatment carried out with the patients was only pharmacologic. The most used drugs for the treatment of PIFP and PPTTN were clonazepam (50%, n=9) and amitriptyline (44.44%, n=8). However, a 55.5% (n=10) of the patients with PIFP or PPTTN required the association of two or more drugs for a correct pain control. All the patients with BMS responded satisfactorily to clonazepam. Conclusions Continuous Neuropathic Orofacial Pain is a little known condition among the general population, physicians and dentists. This favors a late diagnosis and inaccurate treatments which entail unnecessary suffering. It is important to inform both the general population and health professionals concerning this painful condition. Key words:Continuous neuropathic orofacial pain, persistent idiopathic facial pain, painful post-traumatic trigeminal neuropathy

  9. Continuous neurophatic orofacial pain: A retrospective study of 23 cases.

    PubMed

    Sotorra-Figuerola, Dídac; Sánchez-Torres, Alba; Valmaseda-Castellón, Eduard; Gay-Escoda, Cosme

    2016-04-01

    To determine the clinical characteristics of Continuous Neuropathic Orofacial Pain in patients that suffer Persistent Idiopathic Facial Pain (PIFP), Painful Post-Traumatic Trigeminal Neuropathy (PPTTN) or Burning Mouth Syndrome (BMS) and to describe their treatment. A retrospective observational study was made, reviewing the clinical history of the patients diagnosed with Continuous Neuropathic Orofacial Pain between 2004 and 2011 at the Orofacial Pain Unit of the Master of Oral Surgery and Implantology of the University of Barcelona and at the Orofacial Pain Unit of the Teknon Medical Center of Barcelona. The average age of the patients with Continuous Neuropathic Orofacial Pain was 54.5, with a clear female predominance (86.9%, n=20). Of all patients, 60.9% (n=14) were suffering a PIFP, 21.7% (n=5) had a BMS and 17.4% (n=4) were presenting a PPTTN. The pain quality described by the patients with Continuous Neuropathic Orofacial Pain was oppressive (43.47%, n=10), widely represented by patients with PIFP, and burning (39.13%, n=9) being the only quality that described patients with BMS. The treatment carried out with the patients was only pharmacologic. The most used drugs for the treatment of PIFP and PPTTN were clonazepam (50%, n=9) and amitriptyline (44.44%, n=8). However, a 55.5% (n=10) of the patients with PIFP or PPTTN required the association of two or more drugs for a correct pain control. All the patients with BMS responded satisfactorily to clonazepam. Continuous Neuropathic Orofacial Pain is a little known condition among the general population, physicians and dentists. This favors a late diagnosis and inaccurate treatments which entail unnecessary suffering. It is important to inform both the general population and health professionals concerning this painful condition. Continuous neuropathic orofacial pain, persistent idiopathic facial pain, painful post-traumatic trigeminal neuropathy, burning mouth syndrome, atypical odontalgia.

  10. Experimental Muscle Pain Impairs the Synergistic Modular Control of Neck Muscles.

    PubMed

    Gizzi, Leonardo; Muceli, Silvia; Petzke, Frank; Falla, Deborah

    2015-01-01

    A motor task can be performed via different patterns of muscle activation that show regularities that can be factorized in combinations of a reduced number of muscle groupings (also referred to as motor modules, or muscle synergies). In this study we evaluate whether an acute noxious stimulus induces a change in the way motor modules are combined to generate movement by neck muscles. The neck region was selected as it is a region with potentially high muscular redundancy. We used the motor modules framework to assess the redistribution of muscular activity of 12 muscles (6 per side) in the neck region of 8 healthy individuals engaged in a head and neck aiming task, in non-painful conditions (baseline, isotonic saline injection, post pain) and after the injection of hypertonic saline into the right splenius capitis muscle. The kinematics of the task was similar in the painful and control conditions. A general decrease of activity was noted for the injected muscle during the painful condition together with an increase or decrease of the activity of the other muscles. Subjects did not adopt shared control strategies (motor modules inter subject similarity at baseline 0.73±0.14); the motor modules recorded during the painful condition could not be used to reconstruct the activation patterns of the control conditions, and the painful stimulus triggered a subject-specific redistribution of muscular activation (i.e., in some subjects the activity of a given muscle increased, whereas in other subjects it decreased with pain). Alterations of afferent input (i.e., painful stimulus) influenced motor control at a multi muscular level, but not kinematic output. These findings provide new insights into the motor adaptation to pain.

  11. Prices need no preferences: social trends determine decisions in experimental markets for pain relief.

    PubMed

    Vlaev, Ivo; Seymour, Ben; Chater, Nick; Winston, Joel S; Yoshida, Wako; Wright, Nicholas; Symmonds, Mkael; Dolan, Ray

    2014-01-01

    A standard view in health economics is that, although there is no market that determines the "prices" for health states, people can nonetheless associate health states with monetary values (or other scales, such as quality adjusted life year [QALYs] and disability adjusted life year [DALYs]). Such valuations can be used to shape health policy, and a major research challenge is to elicit such values from people; creating experimental "markets" for health states is a theoretically attractive way to address this. We explore the possibility that this framework may be fundamentally flawed-because there may not be any stable values to be revealed. Instead, perhaps people construct ad hoc values, influenced by contextual factors, such as the observed decisions of others. The participants bid to buy relief from equally painful electrical shocks to the leg and arm in an experimental health market based on an interactive second-price auction. Thirty subjects were randomly assigned to two experimental conditions where the bids by "others" were manipulated to follow increasing or decreasing price trends for one, but not the other, pain. After the auction, a preference test asked the participants to choose which pain they prefer to experience for a longer duration. Players remained indifferent between the two pain-types throughout the auction. However, their bids were differentially attracted toward what others bid for each pain, with overbidding during decreasing prices and underbidding during increasing prices. Health preferences are dissociated from market prices, which are strongly referenced to others' choices. This suggests that the price of health care in a free-market has the capacity to become critically detached from people's underlying preferences. 2014 APA, all rights reserved

  12. The effects of experimental muscle and skin pain on the static stretch sensitivity of human muscle spindles in relaxed leg muscles

    PubMed Central

    Birznieks, Ingvars; Burton, Alexander R; Macefield, Vaughan G

    2008-01-01

    Animal studies have shown that noxious inputs onto γ-motoneurons can cause an increase in the activity of muscle spindles, and it has been proposed that this causes a fusimotor-driven increase in muscle stiffness that is believed to underlie many chronic pain syndromes. To test whether experimental pain also acts on the fusimotor system in humans, unitary recordings were made from 19 spindle afferents (12 Ia, 7 II) located in the ankle and toe extensors or peronei muscles of awake human subjects. Muscle pain was induced by bolus intramuscular injection of 0.5 ml 5% hypertonic saline into tibialis anterior (TA); skin pain was induced by 0.2 ml injection into the overlying skin. Changes in fusimotor drive to the muscle spindles were inferred from changes in the mean discharge frequency and discharge variability of spindle endings in relaxed muscle. During muscle pain no afferents increased their discharge activity: seven afferents (5 Ia, 2 II) showed a decrease and six (4 Ia, 2 II) afferents were not affected. During skin pain of 13 afferents discharge rate increased in one (Ia) and decreased in two (1 Ia, 1 II). On average, the overall discharge rate decreased during muscle pain by 6.1% (P < 0.05; Wilcoxon), but remained essentially the same during skin pain. There was no detectable correlation between subjective pain level and the small change in discharge rate of muscle spindles. Irrespective of the type of pain, discharge variability parameters were not influenced (P > 0.05; Wilcoxon). We conclude that, contrary to the ‘vicious cycle’ hypothesis, acute activation of muscle or skin nociceptors does not cause a reflex increase in fusimotor drive in humans. Rather, our results are more aligned with the pain adaptation model, based on clinical studies predicting pain-induced reductions of agonist muscle activity. PMID:18403422

  13. Influence of Polymorphisms in the HTR3A and HTR3B Genes on Experimental Pain and the Effect of the 5-HT3 Antagonist Granisetron

    PubMed Central

    Hedenberg-Magnusson, Britt; List, Thomas; Svensson, Peter; Schalling, Martin

    2016-01-01

    The aim of this study was to investigate experimentally if 5-HT3 single nucleotide polymorphisms (SNP) contribute to pain perception and efficacy of the 5-HT3-antagonist granisetron and sex differences. Sixty healthy participants were genotyped regarding HTR3A (rs1062613) and HTR3B (rs1176744). First, pain was induced by bilateral hypertonic saline injections (HS, 5.5%, 0.2 mL) into the masseter muscles. Thirty min later the masseter muscle on one side was pretreated with 0.5 mL granisetron (1 mg/mL) and on the other side with 0.5 mL placebo (isotonic saline) followed by another HS injection (0.2 mL). Pain intensity, pain duration, pain area and pressure pain thresholds (PPTs) were assessed after each injection. HS evoked moderate pain, with higher intensity in the women (P = 0.023), but had no effect on PPTs. None of the SNPs influenced any pain variable in general, but compared to men, the pain area was larger in women carrying the C/C (HTR3A) (P = 0.015) and pain intensity higher in women with the A/C alleles (HTR3B) (P = 0.019). Pre-treatment with granisetron reduced pain intensity, duration and area to a lesser degree in women (P < 0.05), but the SNPs did not in general influence the efficacy of granisetron. Women carrying the C/T & T/T (HTR3A) genotype had less reduction of pain intensity (P = 0.041) and area (P = 0.005), and women with the C/C genotype (HTR3B) had less reduction of pain intensity (P = 0.030), duration (P = 0.030) and area compared to men (P = 0.017). In conclusion, SNPs did not influence experimental muscle pain or the effect of granisetron on pain variables in general, but there were some sex differences in pain variables that seem to be influenced by genotypes. However, due to the small sample size further research is needed before any firm conclusions can be drawn. PMID:28002447

  14. Experimental muscle pain decreases the frequency threshold of electrically elicited muscle cramps.

    PubMed

    Serrao, Mariano; Arendt-Nielsen, Lars; Ge, Hong-You; Pierelli, Francesco; Sandrini, Giorgio; Farina, Dario

    2007-09-01

    This study in humans tested the hypothesis that nociceptive muscle afferent input facilitates the occurrence of muscle cramps. In 13 healthy adults, muscle cramps were experimentally induced in the foot by stimulating the tibialis posterior nerve at the ankle with 2-s bursts of stimuli separated by 30 s, with stimulation frequency increasing by 2-Hz increments from 10 Hz until the cramp appeared. The minimum stimulation frequency that induced the cramp was defined "cramp frequency threshold". In 2 days, elicitation of the cramp was performed in the two-feet with and without (baseline condition) injection of hypertonic (painful condition) or isotonic (control condition) saline into the deep midportion of the flexor hallucis brevis muscle, from where surface EMG signals were recorded. The cramp frequency threshold was lower for the painful condition with respect to its baseline (mean +/- SE, hypertonic saline: 25.7 +/- 2.1 Hz, corresponding baseline: 31.2 +/- 2.8 Hz; P < 0.01) while there was no difference between the threshold with isotonic injection with respect to baseline. EMG average rectified value and power spectral frequency were higher during the cramp than immediately before the stimulation that elicited the cramp (pre-cramp: 13.9 +/- 1.6 muV and 75.4 +/- 3.8 Hz, respectively; post-cramp: 19.9 +/- 3.2 muV and 101.6 +/- 6.0 Hz; P < 0.05). The results suggest that nociceptive muscle afferent activity induced by injection of hypertonic saline facilitates the generation of electrically elicited muscle cramps.

  15. Experimental muscle pain produces central modulation of proprioceptive signals arising from jaw muscle spindles.

    PubMed

    Capra, N F; Ro, J Y

    2000-05-01

    The aim of the present study was to investigate the effects of intramuscular injection with hypertonic saline, a well-established experimental model for muscle pain, on central processing of proprioceptive input from jaw muscle spindle afferents. Fifty-seven cells were recorded from the medial edge of the subnucleus interpolaris (Vi) and the adjacent parvicellular reticular formation from 11 adult cats. These cells were characterized as central units receiving jaw muscle spindle input based on their responses to electrical stimulation of the masseter nerve, muscle palpation and jaw stretch. Forty-five cells, which were successfully tested with 5% hypertonic saline, were categorized as either dynamic-static (DS) (n=25) or static (S) (n=20) neurons based on their responses to different speeds and amplitudes of jaw movement. Seventy-six percent of the cells tested with an ipsilateral injection of hypertonic saline showed a significant modulation of mean firing rates (MFRs) during opening and/or holding phases. The most remarkable saline-induced change was a significant reduction of MFR during the hold phase in S units (100%, 18/18 modulated). Sixty-nine percent of the DS units (11/16 modulated) also showed significant changes in MFRs limited to the hold phase. However, in the DS neurons, the MFRs increased in seven units and decreased in four units. Finally, five DS neurons showed significant changes of MFRs during both opening and holding phases. Injections of isotonic saline into the ipsilateral masseter muscle had little effect, but hypertonic saline injections made into the contralateral masseter muscle produced similar results to ipsilateral injections with hypertonic saline. These results unequivocally demonstrate that intramuscular injection with an algesic substance, sufficient to produce muscle pain, produces significant changes in the proprioceptive properties of the jaw movement-related neurons. Potential mechanisms involved in saline-induced changes in the

  16. Pilot study of a compassion meditation intervention in chronic pain

    PubMed Central

    Chapin, Heather L; Darnall, Beth D; Seppala, Emma M; Doty, James R; Hah, Jennifer M; Mackey, Sean C

    2016-01-01

    Background The emergence of anger as an important predictor of chronic pain outcomes suggests that treatments that target anger may be particularly useful within the context of chronic pain. Eastern traditions prescribe compassion cultivation to treat persistent anger. Compassion cultivation has been shown to influence emotional processing and reduce negativity bias in the contexts of emotional and physical discomfort, thus suggesting it may be beneficial as a dual treatment for pain and anger. Our objective was to conduct a pilot study of a 9-week group compassion cultivation intervention in chronic pain to examine its effect on pain severity, anger, pain acceptance and pain-related interference. We also aimed to describe observer ratings provided by patients’ significant others and secondary effects of the intervention. Methods Pilot clinical trial with repeated measures design that included a within-subjects wait-list control period. Twelve chronic pain patients completed the intervention (F= 10). Data were collected from patients at enrollment, treatment baseline and post-treatment; participant significant others contributed data at the enrollment and post-treatment time points. Results In this predominantly female sample, patients had significantly reduced pain severity and anger and increased pain acceptance at post-treatment compared to treatment baseline. Significant other qualitative data corroborated patient reports for reductions in pain severity and anger. Conclusions Compassion meditation may be a useful adjunctive treatment for reducing pain severity and anger, and for increasing chronic pain acceptance. Patient reported reductions in anger were corroborated by their significant others. The significant other corroborations offer a novel contribution to the literature and highlight the observable emotional and behavioral changes in the patient participants that occurred following the compassion intervention. Future studies may further examine how

  17. Acute effect of Aloe vera gel extract on experimental models of pain.

    PubMed

    Rathor, Naveen; Mehta, Ashish K; Sharma, Amit K; Mediratta, Pramod K; Sharma, Krishna K

    2012-12-01

    The present study was performed to explore the effect of aqueous extract of Aloe vera on behavioural parameters of pain. Pain assessment was performed by the tail-flick and formalin tests. A. vera (100 mg/kg, per oral (p.o.)) produced an insignificant decrease in the pain response in the tail-flick and formalin tests. Moreover, A. vera (200 and 400 mg/kg, p.o.) did not have significant effect on the tail-flick test. However, A. vera (200 and 400 mg/kg, p.o.) significantly decreased the second phase of the formalin-induced pain. Thus, these findings suggest that A. vera exerts its effect by a peripheral mechanism of action rather than central.

  18. Pain in diabetic neuropathy case study: whole patient management.

    PubMed

    Marchettini, P; Teloni, L; Formaglio, F; Lacerenza, M

    2004-04-01

    Painful diabetic peripheral neuropathy (DPN) is described as a superficial burning pain associated with other positive and/or negative sensory systems affecting the feet and lower extremities. It is one of the most commonly encountered neuropathic pain syndromes in clinical practice. Presentation may be complicated by multiple symptoms, including allodynia, hyperalgesia, other less well characterized dysesthesias, and serious disruption of social functioning and mood. Peripheral nerve function may deteriorate, which can account for patient reports of diminution of pain after several years of follow-up. Although current understanding holds that the pathogenesis of DPN is multifactorial in nature, long-term studies have shown that rigorous glycemic control is the most relevant factor in clinical intervention and can delay the onset and slow the progression of neuropathy. In addition to glycemic control, other treatment approaches must be examined in order to restore quality of life for patients experiencing painful DPN. Differential diagnosis is required to isolate DPN from other unexplained chronic pain. Neurologic testing in painful DPN is an area of active research and is used to assess the neurologic pathways giving rise to the pain, the degree of neural damage and the degree of subclinical damage. Current treatment options for DPN include mainly antidepressants and anticonvulsants, with other agents such as tramadol, dextromethorphan and memantine being employed or studied. This review article includes a case study of a patient with painful DPN to demonstrate the current management strategies for this neuropathic pain syndrome.

  19. Conditioned Pain Modulation and Situational Pain Catastrophizing as Preoperative Predictors of Pain following Chest Wall Surgery: A Prospective Observational Cohort Study

    PubMed Central

    Grosen, Kasper; Vase, Lene; Pilegaard, Hans K.; Pfeiffer-Jensen, Mogens; Drewes, Asbjørn M.

    2014-01-01

    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

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

    PubMed

    Grosen, Kasper; Vase, Lene; Pilegaard, Hans K; Pfeiffer-Jensen, Mogens; Drewes, Asbjørn M

    2014-01-01

    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. 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. 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). 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

  1. Influence of topical capsaicin on facial sensitivity in response to experimental pain.

    PubMed

    Lee, Y-S; Kho, H-S; Kim, Y-K; Chung, S-C

    2007-01-01

    Capsaicin, the pungent component of the red pepper, has been used as an analgesic in a variety of pain conditions, but sensory impairment after long-term treatment has been concerned. This study investigated the influence of topical capsaicin on various types of sensations including pain in the facial areas innervated by the mental nerve, and also evaluated whether the measurement of cutaneous current perception threshold (CPT) is reliable for the quantification of sensory change following capsaicin application. Twenty healthy subjects were given topical capsaicin cream (0.075%), which was applied to the mental area unilaterally, four times daily for 2 weeks. Burning sensation after capsaicin application gradually decreased with repeated applications. Repeated topical capsaicin resulted in reduced sensation to mechanical, heat and cold pain without changing non-painful tactile sensation. It also resulted in increased CPTs at 5 Hz and 250 Hz stimuli but no change in the CPTs at 2000 Hz from the first evaluation after capsaicin treatment and throughout the treatment period. This study demonstrated that topical capsaicin treatment for the management of chronic localized pain can be safely applied to the face without affecting non-painful normal sensations, and that CPT testing is a clinically useful tool for the quantification of sensory changes following capsaicin application.

  2. The representation of experimental tooth pain from upper and lower jaws in the human trigeminal pathway.

    PubMed

    Weigelt, A; Terekhin, P; Kemppainen, P; Dörfler, A; Forster, C

    2010-06-01

    FMRI was used to study the differences of cerebral processing of nociceptive input from the 2nd and the 3rd branches of the trigeminal nerve by electrical stimulation of the tooth pulps of the upper and lower canines. The focus of the study was an investigation of the different levels of the trigeminal system in brainstem, thalamus and in cortical regions which are known to be involved in pain processing. Increased blood oxygen level dependency (BOLD) signals were found ipsilaterally in the trigeminal ganglion and the spinal nucleus (SpV) of the trigeminal nerve. SpV-related activations showed some somatotopic organization. Bilateral activation was found in the structures of the antinociceptive system in the midbrain. Contralateral activations were encountered at the level of the pons. In the thalamus ipsilateral activations were found in the ventral parts. Bilateral activation occurred in the medial dorsal nuclei. At the cortical level BOLD activations were encountered bilaterally in the primary somatosensory cortex (S1, lateral pain system), the cingulate and insular cortex (medial pain system). In the cortex a small difference in the representation of the two trigeminal branches was detected only in S1 on both hemispheres. These findings demonstrate that trigeminal pain markedly activates the lateral and medial pain projection systems and the majority of the affected brain regions showed no difference regarding the input from lower or upper tooth. This lack of discrimination may explain why sometimes it is difficult for patients to locate the exact source of the intraoral clinical pain conditions.

  3. Pain.

    PubMed

    Melzack, Ronald; Katz, Joel

    2013-01-01

    Pain has many valuable functions. It often signals injury or disease, generates a wide range of adaptive behaviors, and promotes healing through rest. Despite these beneficial aspects of pain, there are negative features that challenge our understanding of the puzzle of pain, including persistent phantom limb pain after amputation or total spinal cord transection. Pain is a personal, subjective experience influenced by cultural learning, the meaning of the situation, attention, and other psychological variables. Pain processes do not begin with the stimulation of receptors. Rather, injury or disease produces neural signals that enter an active nervous system that (in the adult organism) is the substrate of past experience, culture, and a host of other environmental and personal factors. These brain processes actively participate in the selection, abstraction, and synthesis of information from the total sensory input. Pain is not simply the end product of a linear sensory transmission system; it is a dynamic process that involves continuous interactions among complex ascending and descending systems. The neuromatrix theory guides us away from the Cartesian concept of pain as a sensation produced by injury, inflammation, or other tissue pathology and toward the concept of pain as a multidimensional experience produced by multiple influences. These influences range from the existing synaptic architecture of the neuromatrix-which is determined by genetic and sensory factors-to influences from within the body and from other areas in the brain. Genetic influences on synaptic architecture may determine-or predispose toward-the development of chronic pain syndromes. WIREs Cogn Sci 2013, 4:1-15. doi: 10.1002/wcs.1201 For further resources related to this article, please visit the WIREs website.

  4. Neurophysiologic studies in congenital insensitivity to pain with anhidrosis.

    PubMed

    Shorer, Z; Moses, S W; Hershkovitz, E; Pinsk, V; Levy, J

    2001-11-01

    Thirteen patients with congenital insensitivity to pain and anhidrosis, carrying a mutation at the TRK-A gene, were studied. Neurologic examination revealed vestigial pain sensitivity, suggesting an incomplete involvement of the affected nerves. All 13 patients manifested normal electrophysiologic studies but striking absence of sympathetic skin responses. We suggest the use of the sympathetic skin response test in the clinical evaluation of patients suspected of having congenital insensitivity to pain and anhidrosis.

  5. Pain Ratings, Psychological Functioning and Quantitative EEG in a Controlled Study of Chronic Back Pain Patients

    PubMed Central

    Schmidt, Stefan; Naranjo, José Raúl; Brenneisen, Christina; Gundlach, Julian; Schultz, Claudia; Kaube, Holger; Hinterberger, Thilo; Jeanmonod, Daniel

    2012-01-01

    Objectives Several recent studies report the presence of a specific EEG pattern named Thalamocortical Dysrhythmia (TCD) in patients with severe chronic neurogenic pain. This is of major interest since so far no neuroscientific indicator of chronic pain could be identified. We investigated whether a TCD-like pattern could be found in patients with moderate chronic back pain, and we compared patients with neuropathic and non-neuropathic pain components. We furthermore assessed the presence of psychopathology and the degree of psychological functioning and examined whether the strength of the TCD-related EEG markers is correlated with psychological symptoms and pain ratings. Design Controlled clinical trial with age and sex matched healthy controls. Methods Spontaneous EEG was recorded in 37 back pain patients and 37 healthy controls. Results We were not able to observe a statistically significant TCD effect in the EEG data of the whole patient group, but a subsample of patients with evidence for root damage showed a trend in this direction. Pain patients showed markedly increased psychopathology. In addition, patients' ratings of pain intensity within the last 1 to 12 months showed strong correlations with EEG power, while psychopathology was correlated to the peak frequency. Conclusion Out of several possible interpretations the most likely conclusion is that only patients with severe pain as well as root lesions with consecutive thalamic deafferentation develop the typical TCD pattern. Our primary method of defining ‘neuropathic pain’ could not reliably determine if such a deafferentation was present. Nevertheless the analysis of a specific subsample as well as correlations between pain ratings, psychopathology and EEG power and peak frequency give some support to the TCD concept. Trial Registration ClinicalTrials.gov NCT00744575 PMID:22431961

  6. An Epidemiological Study of Neuropathic Pain Symptoms in Canadian Adults

    PubMed Central

    VanDenKerkhof, Elizabeth G.; Mann, Elizabeth G.; Torrance, Nicola; Smith, Blair H.; Johnson, Ana; Gilron, Ian

    2016-01-01

    The reported prevalence of neuropathic pain ranges from 6.9% to 10%; however the only Canadian study reported 17.9%. The objective of this study was to describe the epidemiology of neuropathic pain in Canada. A cross-sectional survey was conducted in a random sample of Canadian adults. The response rate was 21.1% (1504/7134). Likely or possible neuropathic pain was defined using a neuropathic pain-related diagnosis and a positive outcome on the Self-Report Leeds Assessment of Neuropathic Symptoms and Signs pain scale (S-LANSS) or the Douleur Neuropathique 4 (DN4) Questions. The prevalence of likely neuropathic pain was 1.9% (S-LANSS) and 3.4% (DN4) and that of possible neuropathic pain was 5.8% (S-LANSS) and 8.1% (DN4). Neuropathic pain was highest in economically disadvantaged males. There is a significant burden of neuropathic pain in Canada. The low response rate and a slightly older and less educated sample than the Canadian population may have led to an overestimate of neuropathic pain. Population prevalence varies by screening tool used, indicating more work is needed to develop reliable measures. Population level screening targeted towards high risk groups should improve the sensitivity and specificity of screening, while clinical examination of those with positive screening results will further refine the estimate of prevalence. PMID:27445636

  7. Lumbosacral pain in ballet school students. Pilot study.

    PubMed

    Drężewska, Marlena; Śliwiński, Zbigniew

    2013-01-01

    The unique biomechanical demands placed on ballet students predispose to injury and pain. The aim of this study was to evaluate the prevalence of lumbosacral pain in ballet school students and to identify possible risk factors for the pain. The study group comprised 71 ballet school students, including 45 females and 26 males, aged 15-18 years (mean 16.5 years). In order to identify possible risk factors for pain, a survey was conducted, the angle of sacral bone inclination was measured using a mechanical inclinometer and the BMI was calculated. A VAS scale was used for a subjective assessment of pain intensity. Low back pain was reported by 44 patients (62%). A comparison of sacral inclination angles in a position with the feet placed parallel and in the turnout position showed statistically significant changes in the angle among respondents reporting pain (p <0.05). 1. Compensation in the turnout position by increas ed anterior tilt of the pelvis may increase the risk of low back pain. 2. An angle of sacral bone inclination in turnout above or equal to 30° can increase the intensity of low back pain. 3. A BMI below 18.5 in female ballet school stu dents can increase the risk of lumbosacral pain.

  8. Effect of muscle relaxants on experimental jaw-muscle pain and jaw-stretch reflexes: a double-blind and placebo-controlled trial.

    PubMed

    Svensson, Peter; Wang, Kelun; Arendt-Nielsen, Lars

    2003-01-01

    A randomised, double-blind, placebo-controlled three-way cross-over study was performed to investigate the effect of two muscle relaxants (tolperisone hydrochloride and pridinol mesilate) on experimental jaw-muscle pain and jaw-stretch reflexes. Fifteen healthy men participated in three randomised sessions separated by at least 1 week. In each session 300 mg tolperisone, 8 mg pridinol mesilate or placebo was administered orally as a single dose. One hour after drug administration 0.3 ml hypertonic saline (5.8%) was injected into the right masseter to produce muscle pain. Subjects continuously rated their perceived pain intensity on an electronic 10-cm visual analogue scale (VAS). The pressure pain threshold (PPT) was measured and short-latency reflex responses were evoked in the pre-contracted (15% maximal voluntary contraction) masseter and temporalis muscles by a standardised stretch device (1 mm displacement, 10 ms ramp time) before (baseline), 1 h after medication (post-drug), during ongoing experimental muscle pain (pain-post-drug), and 15 min after pain had vanished (post-pain). Analysis of variance demonstrated significantly lower VAS peak pain scores (5.9 +/- 0.4 cm) after administration of tolperisone hydrochloride compared with pridinol mesilate (6.8 +/- 0.4 cm) and placebo (6.6 +/- 0.4 cm) (P=0.020). Administration of pridinol mesilate was associated with a significant decrease in PPTs compared with tolperisone hydrochloride and placebo (P=0.002) after medication, but not after experimental jaw-muscle pain. The normalised peak-to-peak amplitude of the stretch reflexes were not significantly influenced by the test medication (P=0.762), but were in all sessions significantly facilitated during ongoing experimental jaw-muscle pain (P=0.034). In conclusion, tolperisone hydrochloride provides a small, albeit significant reduction in the perceived intensity of experimental jaw-muscle pain whereas the present dose had no effect on the short-latency jaw

  9. Effectiveness of a community based nurse-pharmacist managed pain clinic: A mixed-methods study.

    PubMed

    Hadi, Muhammad Abdul; Alldred, David Phillip; Briggs, Michelle; Marczewski, Kathryn; Closs, S José

    2016-01-01

    Chronic pain is predominantly managed in primary care, although often ineffectively. There is growing evidence to support the potential role of nurses and pharmacists in the effective management of chronic pain. To evaluate the effectiveness of a pain clinic jointly managed by a nurse and pharmacist. A mixed-methods design consisting of qualitative interviews embedded within a quasi-experimental study. A community-based nurse-pharmacist led pain clinic in the north of England. Adult chronic pain (non-malignant) patients referred to the pain clinic. Pain intensity was the primary outcome. Questionnaires (the Brief Pain Inventory, the Hospital Anxiety and Depression Scale, the SF-36 and the Chronic Pain Grade questionnaire) were administered at the baseline, on discharge and at 3-month post-discharge (Brief Pain Inventory and Hospital Anxiety and Depression Scale only). Patient satisfaction was explored using face-to-face, semi-structured qualitative interviews. Seventy-nine patients with a mean age of 46.5 years (SD±14.4) took part in the quasi-experimental study. Thirty-six and nine patients completed the discharge and 3-month follow-up questionnaires respectively. Compared to baseline, statistically significant reductions were noted for two of the outcome measures: pain intensity (P=0.02), and interference of pain with physical functioning (P=0.02) on discharge from the service. Nineteen patients participated in qualitative interviews. The patients were, in general, satisfied with the quality of service. Four contributing factors to patient satisfaction were identified: ample consultation time, in-depth specialised knowledge, listening and understanding to patients' needs, and a holistic approach. Nurse and pharmacist managed community-based pain clinics can effectively deliver quality pain management services as they offer an interdisciplinary holistic approach to pain management. Such services have the potential not only to reduce the burden on secondary care

  10. Distinctive subgroups derived by cluster analysis based on pain and psychological symptoms in Swedish older adults with chronic pain - a population study (PainS65+).

    PubMed

    Larsson, Britt; Gerdle, Björn; Bernfort, Lars; Levin, Lars-Åke; Dragioti, Elena

    2017-09-02

    Improved knowledge based on clinical features of chronic pain in older adults would be valuable in terms of patient-orientated approaches and would provide support for health care systems in optimizing health care resources. This study identifies subgroups based on pain and psychological symptoms among Swedish older adults in the general population and compares derived subgroups with respect to socio-demographics, health aspects, and health care costs. This cross-sectional study uses data collected from four registers and one survey. The total sample comprised 2415 individuals ≥65 years old. A two-step cluster analysis was performed. Data on pain intensity, number of pain sites, anxiety, depression, and pain catastrophizing were used as classification variables. Differences in socio-demographics, quality of life, general health, insomnia, and health care costs among the clusters were investigated. Association of the clusters with the above parameters was further evaluated using multinomial logistic regression. Four major clusters were identified: Subgroup 1 (n = 325; 15%) - moderate pain and high psychological symptoms; Subgroup 2 (n = 516; 22%) - high pain and moderate psychological symptoms; Subgroup 3 (n = 686; 30%) - low pain and moderate psychological symptoms; and Subgroup 4 (n = 767; 33%) - low pain and low psychological symptoms. Significant differences were found between the four clusters with regard to age, sex, educational level, family status, quality of life, general health, insomnia, and health care costs. The multinomial logistic regression analysis revealed that Subgroups 1 and 2, compared to Subgroup 4, were significantly associated with decreased quality of life, decreased general health, and increased insomnia. Subgroup 3, compared to Subgroup 4, was associated with decreased general health and increased insomnia. In addition, compared to Subgroup 4, Subgroups 1 and 2 were significantly associated with higher health care costs. Two

  11. Postoperative patients' perspectives on rating pain: A qualitative study.

    PubMed

    van Dijk, Jacqueline F M; Vervoort, Sigrid C J M; van Wijck, Albert J M; Kalkman, Cor J; Schuurmans, Marieke J

    2016-01-01

    In postoperative pain treatment patients are asked to rate their pain experience on a single uni-dimensional pain scale. Such pain scores are also used as indicator to assess the quality of pain treatment. However, patients may differ in how they interpret the Numeric Rating Scale (NRS) score. This study examines how patients assign a number to their currently experienced postoperative pain and which considerations influence this process. A qualitative approach according to grounded theory was used. Twenty-seven patients were interviewed one day after surgery. Three main themes emerged that influenced the Numeric Rating Scale scores (0-10) that patients actually reported to professionals: score-related factors, intrapersonal factors, and the anticipated consequences of a given pain score. Anticipated consequences were analgesic administration-which could be desired or undesired-and possible judgements by professionals. We also propose a conceptual model for the relationship between factors that influence the pain rating process. Based on patients' score-related and intrapersonal factors, a preliminary pain score was "internally" set. Before reporting the pain score to the healthcare professional, patients considered the anticipated consequences (i.e., expected judgements by professionals and anticipation of analgesic administration) of current Numeric Rating Scale scores. This study provides insight into the process of how patients translate their current postoperative pain into a numeric rating score. The proposed model may help professionals to understand the factors that influence a given Numeric Rating Scale score and suggest the most appropriate questions for clarification. In this way, patients and professionals may arrive at a shared understanding of the pain score, resulting in a tailored decision regarding the most appropriate treatment of current postoperative pain, particularly the dosing and timing of opioid administration. Copyright © 2015 Elsevier

  12. Effects of far-infrared irradiation on myofascial neck pain: a randomized, double-blind, placebo-controlled pilot study.

    PubMed

    Lai, Chien-Hung; Leung, Ting-Kai; Peng, Chih-Wei; Chang, Kwang-Hwa; Lai, Ming-Jun; Lai, Wen-Fu; Chen, Shih-Ching

    2014-02-01

    The objective of this study was to determine the relative efficacy of irradiation using a device containing a far-infrared emitting ceramic powder (cFIR) for the management of chronic myofascial neck pain compared with a control treatment. This was a randomized, double-blind, placebo-controlled pilot study. The study comprised 48 patients with chronic, myofascial neck pain. Patients were randomly assigned to the experimental group or the control (sham-treatment) group. The patients in the experimental group wore a cFIR neck device for 1 week, and the control group wore an inert neck device for 1 week. Quantitative measurements based on a visual analogue scale (VAS) scoring of pain, a sleep quality assessment, pressure-pain threshold (PPT) testing, muscle tone and compliance analysis, and skin temperature analysis were obtained. Both the experimental and control groups demonstrated significant improvement in pain scores. However, no statistically significant difference in the pain scores was observed between the experimental and control groups. Significant decreases in muscle stiffness in the upper regions of the trapezius muscles were reported in the experimental group after 1 week of treatment. Short-term treatment using the cFIR neck device partly reduced muscle stiffness. Although the differences in the VAS and PPT scores for the experimental and control groups were not statistically significant, the improvement in muscle stiffness in the experimental group warrants further investigation of the long-term effects of cFIR treatment for pain management.

  13. Pain perception studies in tension-type headache.

    PubMed

    Bezov, David; Ashina, Sait; Jensen, Rigmor; Bendtsen, Lars

    2011-02-01

    Tension-type headache (TTH) is a disorder with high prevalence and significant impact on society. Understanding of pathophysiology of TTH is paramount for development of effective treatments and prevention of chronification of TTH. Our aim was to review the findings from pain perception studies of pathophysiology of TTH as well as to review the research of pathophysiology of TTH. Pain perception studies such as measurement of muscle tenderness, pain detection thresholds, pain tolerance thresholds, pain response to suprathreshold stimulation, temporal summation and diffuse noxious inhibitory control (DNIC) have played a central role in elucidating the pathophysiology of TTH. It has been demonstrated that continuous nociceptive input from peripheral myofascial structures may induce central sensitization and thereby chronification of the headache. Measurements of pain tolerance thresholds and suprathreshold stimulation have shown presence of generalized hyperalgesia in chronic tension-type headache (CTTH) patients, while DNIC function has been shown to be reduced in CTTH. One imaging study showed loss of gray matter structures involved in pain processing in CTTH patients. Future studies should aim to integrate pain perception and imaging to confirm this finding. Pharmacological studies have shown that drugs like tricyclic anti-depressant amitriptyline and nitric oxide synthase inhibitors can reverse central sensitization and the chronicity of headache. Finally, low frequency electrical stimulation has been shown to rapidly reverse central sensitization and may be a new modality in treatment of CTTH and other chronic pain disorders. © 2010 American Headache Society.

  14. Hypnotherapy of a pain disorder: a clinical case study.

    PubMed

    Artimon, Henrieta Mihaela

    2015-01-01

    Hypnotherapy's effectiveness in improving and controlling chronic pain of various etiologies has been demonstrated by studies; the mechanism by which hypnosis does this is more complex than a simple induction of muscle relaxation. This study reveals, in addition to this mechanism, a deeper dimension of hypnotherapy from the vantage of a patient with a medical-surgical background, diagnosed with a pain disorder and major severe depressive disorder in addition to incurable painful symptoms, through treatment associated with hypnoanalysis. Following psychotherapy, which included some elements of cognitive-behavioral therapy, a complete remission of the anxious-depressive mood and the painful symptoms was achieved.

  15. Manipulating the Placebo Response in Experimental Pain by Altering Doctor’s Performance Style

    PubMed Central

    Czerniak, Efrat; Biegon, Anat; Ziv, Amitai; Karnieli-Miller, Orit; Weiser, Mark; Alon, Uri; Citron, Atay

    2016-01-01

    Background: Performance is paramount in traditional healing rituals. From a Western perspective, such performative behavior can be understood principally as inducing patients’ faith in the performer’s supernatural healing powers and effecting positive changes through the same mechanisms attributed to the placebo response, which is defined as improvement of clinical outcome in individuals receiving inactive treatment. Here we examined the possibility of using theatrical performance tools, including stage directions and scripting, to reproducibly manipulate the style and content of a simulated doctor–patient encounter and influence the placebo response in experimental pain. Methods: A total of 122 healthy volunteers (18–45 years, 76 men) exposed to experimental pain (the cold pressor test) were assessed for pain threshold and tolerance before and after receiving a placebo cream from a “doctor” impersonated by a trained actor. The actor alternated between two distinct scripts and stage directions, i.e., performance styles created by a theater director/playwright, one emulating a standard doctor–patient encounter (scenario A) and the other emphasizing attentiveness and strong suggestion, elements also present in ritual healing (scenario B). The placebo response size was calculated as the %difference in pain threshold and tolerance after exposure relative to baseline. In addition, subjects demonstrating a ≥30% increase in pain threshold or tolerance relative to baseline were defined as responders. Each encounter was videotaped in its entirety. Results: Inspection of the videotapes confirmed the reproducibility and consistency of the distinct scenarios enacted by the “doctor”-performer. Furthermore, scenario B resulted in a significant increase in pain threshold relative to scenario A. Interestingly, this increase derived from the placebo responder subgroup; as shown by two-way analysis of variance (performance style, F = 4.30; p = 0.040; η2 = 0

  16. Intensive interdisciplinary outpatient pain management program for chronic back pain: a pilot study.

    PubMed

    Artner, Juraj; Kurz, Stephan; Cakir, Balkan; Reichel, Heiko; Lattig, Friederike

    2012-01-01

    Chronic back pain is relatively resistant to unimodal therapy regimes. The aim of this study was to introduce and evaluate the short-term outcome of a three-week intensive multidisciplinary outpatient program for patients with back pain and sciatica, measured according to decrease of functional impairment and pain. The program was designed for patients suffering from chronic back pain to provide intensive interdisciplinary therapy in an outpatient setting, consisting of interventional injection techniques, medication, exercise therapy, back education, ergotherapy, traction, massage therapy, medical training, transcutaneous electrical nerve stimulation, aquatraining, and relaxation. Based on Oswestry Disability Index (ODI) and Numeric Rating Scale (NRS) scores, a significant improvement in pain intensity and functionality of 66.83% NRS and an ODI of 33.33% were achieved by our pain program within 3 weeks. This paper describes the organization and short-term outcome of an intensive multidisciplinary program for chronic back pain on an outpatient basis provided by our orthopedic department, with clinically significant results.

  17. Intensive interdisciplinary outpatient pain management program for chronic back pain: a pilot study

    PubMed Central

    Artner, Juraj; Kurz, Stephan; Cakir, Balkan; Reichel, Heiko; Lattig, Friederike

    2012-01-01

    Background Chronic back pain is relatively resistant to unimodal therapy regimes. The aim of this study was to introduce and evaluate the short-term outcome of a three-week intensive multidisciplinary outpatient program for patients with back pain and sciatica, measured according to decrease of functional impairment and pain. Methods The program was designed for patients suffering from chronic back pain to provide intensive interdisciplinary therapy in an outpatient setting, consisting of interventional injection techniques, medication, exercise therapy, back education, ergotherapy, traction, massage therapy, medical training, transcutaneous electrical nerve stimulation, aquatraining, and relaxation. Results Based on Oswestry Disability Index (ODI) and Numeric Rating Scale (NRS) scores, a significant improvement in pain intensity and functionality of 66.83% NRS and an ODI of 33.33% were achieved by our pain program within 3 weeks. Conclusion This paper describes the organization and short-term outcome of an intensive multidisciplinary program for chronic back pain on an outpatient basis provided by our orthopedic department, with clinically significant results. PMID:22826641

  18. Pain Duration and Resolution Following Surgery: An Inception Cohort Study

    PubMed Central

    Carroll, Ian R.; Hah, Jennifer M.; Barelka, Peter L.; Wang, Charlie KM.; Wang, Bing M.; Gillespie, Matthew J.; McCue, Rebecca; Younger, Jarred W.; Trafton, Jodie; Humphreys, Keith; Goodman, Stuart B.; Dirbas, Fredrick M.; Mackey, Sean C.

    2015-01-01

    Objective Preoperative determinants of pain duration following surgery are poorly understood. We identified preoperative predictors of prolonged pain after surgery in a mixed surgical cohort. Methods We conducted a prospective longitudinal study of patients undergoing mastectomy, lumpectomy, thoracotomy, total knee replacement, or total hip replacement. We measured preoperative psychological distress and substance use, and then measured pain and opioid use after surgery until patients reported the cessation of both opioid consumption and pain. The primary endpoint was time to opioid cessation, and those results have been previously reported. Here we report preoperative determinants of time to pain resolution following surgery in Cox proportional hazards regression. Results Between January 2007 and April 2009 we enrolled 107 of 134 consecutively approached patients undergoing the aforementioned surgical procedures. In the final multivariate model, preoperative self-perceived risk of addiction predicted more prolonged pain. Unexpectedly, anxiety sensitivity predicted more rapid pain resolution after surgery. Each one-point increase (on a four point scale) of self-perceived risk of addiction was associated with a 38% (95% CI 3 - 61) reduction in the rate of pain resolution (p= 0.04). Furthermore, higher anxiety sensitivity was associated with an 89% (95% CI 23–190) increased rate of pain resolution (p=0.004). Conclusions Greater preoperative self-perceived risk of addiction, and lower anxiety sensitivity predicted a slower rate of pain resolution following surgery. Each of these factors was a better predictor of pain duration than preoperative depressive symptoms, PTSD symptoms, past substance use, fear of pain, gender, age, preoperative pain, or preoperative opioid use. PMID:26179223

  19. Characterization of Whole Body Pain in Urologic Chronic Pelvic Pain Syndrome at Baseline – A MAPP Research Network Study

    PubMed Central

    Lai, H. Henry; Jemielita, Thomas; Sutcliffe, Siobhan; Bradley, Catherine S.; Naliboff, Bruce; Williams, David A.; Gereau, Robert W.; Kreder, Karl; Clemens, J. Quentin; Rodriguez, Larissa V.; Krieger, John N.; Farrar, John T.; Robinson, Nancy; Landis, J. Richard

    2017-01-01

    Purpose We characterized the location and spatial distribution of whole body pain among patients with urologic chronic pelvic pain syndrome (UCPPS) using a body map; and compared the severity of urinary symptoms, pelvic pain, non-pelvic pain, and psychosocial health among patients with different pain patterns. Methods 233 women and 191 men with UCPPS enrolled in a multi-center, one-year observational study completed a battery of baseline measures, including a body map describing the location of pain during the past week. Participants were categorized as having “pelvic pain only” if they reported pain in the abdomen and pelvis only. Participants who reported pain beyond the pelvis were further divided into two sub-groups based on the number of broader body regions affected by pain: an “intermediate” group (1–2 additional regions outside the pelvis) and a “widespread pain” group (3–7 additional regions). Results Of the 424 enrolled patients 25% reported pelvic pain only, and 75% reported pain beyond the pelvis of which 38% reported widespread pain. Participants with greater number of pain locations had greater non-pelvic pain severity (p<0.0001), sleep disturbance (p=0.035), depression (p=0.005), anxiety (p=0.011), psychological stress (p=0.005), negative affect scores (p=0.0004), and worse quality of life (p≤0.021). No difference in pelvic pain and urinary symptom severity were observed by increasing pain distribution. Conclusions Three-quarters of men and women with UCPPS reported pain outside the pelvis. Widespread pain was associated with greater severity of non-pelvic pain symptoms, poorer psychosocial health and worse quality of life, but not worse pelvic pain or urinary symptoms. PMID:28373134

  20. The effect of a selective alpha2-adrenoceptor antagonist on pain behavior of the rat varies, depending on experimental parameters.

    PubMed

    Kauppila, T; Jyväsjärvi, E; Hämäläinen, M M; Pertovaara, A

    1998-02-01

    Effects of atipamezole, an alpha2-adrenoceptor antagonist, in various acute pain tests were studied in the rat. Atipamezole (at doses > or = 0.1 mg/kg I.P.) and idazoxan, another alpha2-adrenoceptor antagonist (2.5 mg/kg, I.P.), increased licking latency in the hot-plate test. Bilateral administration of atipamezole (10 microg) into the locus coeruleus did not increase licking latency in the hot-plate test. Medetomidine (an alpha2-adrenoceptor agonist; 1-3 mg/kg) or repeated pre-exposures to the testing apparatus reversed the effect of atipamezole (1.5 mg/kg) in the hot-plate test. Atipamezole also increased the latency to mechanically induced licking/biting response at a dose of 1.5 mg/kg, but not at lower doses. In the heat-induced tail-flick test, in contrast, atipamezole at doses of 0.1 and 1.5 mg/kg produced a medetomidine-reversible decrease of response latencies. This facilitation of the tail-flick response disappeared if the intensity of the heat stimulus was high. At a dose range from 0.03 to 1.5 mg/kg atipamezole did not significantly alter the paw withdrawal latency to noxious mechanical stimulation, nor pain behavior in the formalin test. Responses to nociceptive spinal dorsal horn neurons were not modulated by atipamezole (1 mg/kg) in anesthetized spinalized rats. The results indicate that an alpha2-adrenoceptor antagonist may have variable effects in behavioral pain tests, depending on habituation of the experimental animals to the testing conditions, the dose of the drug, the type of behavioral response and the submodality or the intensity of the noxious test stimulus. The atipamezole-induced changes in pain behavior observed in this study may rather be explained due to action on motor expression of pain than due to modulation of nociception.

  1. Osteoarthritis pain mechanisms: Basic studies in animal models

    PubMed Central

    Zhang, Rui-Xin; Ren, Ke; Dubner, Ronald

    2013-01-01

    Osteoarthritis (OA) is a complex and painful disease of the whole joint. At present there are no satisfying agents for treating OA. The current standard of care mainly involves managing and alleviating its symptoms. Mechanisms of OA pain have been studied in rodent knee OA models produced by intra-knee injection of the chondrocyte glycolytic inhibitor mono-iodoacetate, surgery, or spontaneous development in some species. These models are clinically relevant in terms of histological damage and functional changes, and are used to study mechanisms underlying mechanical, thermal, ambulatory, body weight supporting-evoked, and ongoing OA pain. Recent peripheral, spinal, and supraspinal biochemical and electrophysiological studies in these models suggest that peripheral pro-inflammatory mediators and neuropeptides sensitize knee nociceptors. Spinal cytokines and neuropeptides promote OA-associated pain, and peripheral and spinal cannabinoids inhibit OA pain respectively through cannabinoid-1 (CB1) and CB1/CB2 receptors. TRPV1 and metalloproteinases contribute and supraspinal descending facilitation of 5-HT/5-HT 3 receptors may also contribute to OA pain. Conditioned place preference tests demonstrate that OA pain induces aversive behaviors suggesting brain involvement in OA pain. During OA, brain functional connectivity is enhanced, but at present it is unclear how this change is related to OA pain. PMID:23973145

  2. Early signaling, referral, and treatment of adolescent chronic pain: a study protocol

    PubMed Central

    2012-01-01

    Background Chronic pain is prevalent among young people and negatively influences their quality of life. Furthermore, chronic pain in adolescence may persist into adulthood. Therefore, it is important early on to promote the self-management skills of adolescents with chronic pain by improving signaling, referral, and treatment of these youngsters. In this study protocol we describe the designs of two complementary studies: a signaling study and an intervention study. Methods and design The signaling study evaluates the Pain Barometer, a self-assessed signaling instrument for chronic pain in adolescents. To evaluate the feasibility of the Pain Barometer, the experiences of youth-health care nurses will be evaluated in semi-structured interviews. Also, we will explore the frequencies of referral per health-care provider. The intervention study evaluates Move It Now, a guided self-help intervention via the Internet for teenagers with chronic pain. This intervention uses cognitive behavioural techniques, including relaxation exercises and positive thinking. The objective of the intervention is to improve the ability of adolescents to cope with pain. The efficacy of Move It Now will be examined in a randomized controlled trial, in which 60 adolescents will be randomly assigned to an experimental condition or a waiting list control condition. Discussion If the Pain Barometer is proven to be feasible and Move It Now appears to be efficacious, a health care pathway can be created to provide the best tailored treatment promptly to adolescents with chronic pain. Move It Now can be easily implemented throughout the Netherlands, as the intervention is Internet based. Trial registration Dutch Trial Register NTR1926 PMID:22686133

  3. Influence of Murraya koenigii on experimental model of diabetes and progression of neuropathic pain

    PubMed Central

    Tembhurne, S.V.; Sakarkar, D.M.

    2010-01-01

    The aim of the present study was to evaluate the effect of ethanolic extract of Murraya koenigii leaves (MKL) on blood glucose level and in prevention or management of diabetic neuropathy. In the present study the diabetic neuropathy was developed 9 weeks after single injection of streptozotocin (STZ, 70 mg/kg i.v.) in rat. The treatment with MKL (300 and 500 mg/kg p.o.) was started after stabilization of blood glucose level (13 days after STZ) and evaluated for determination of glycemic level, glycated haemoglobin, grip strength, pain sensitivity and threshold. The result showed that the treatment with MKL possessed hypoglycemic effect in diabetic treated animals. The results also indicated that the decreases in the grip strength in diabetic animals represented the induction of neuropathy 9 weeks after STZ treatment. Prior treatments with MKL increased the grip strength of diabetic rats. The results of pain sensitivity indicated the loss of pain perception in diabetic animals because of nerve damage. While prior treatment with MKL upto 9 week in diabetic animals resulted in the increase in the licking time and withdrawal latency in hot plate and tail flick tests, respectively, which indicates the presence of pain perception and prevention of nerve damage due to protective effect of MKL in progression of diabetic neuropathic pain. Therefore, the present study concludes that the chronic treatment with MKL significantly decreased the glycemic level as well as it protected the animals against development of diabetic neuropathy. PMID:21589767

  4. Characteristics of highly impaired children with severe chronic pain: a 5-year retrospective study on 2249 pediatric pain patients

    PubMed Central

    2012-01-01

    Background Prevalence of pain as a recurrent symptom in children is known to be high, but little is known about children with high impairment from chronic pain seeking specialized treatment. The purpose of this study was the precise description of children with high impairment from chronic pain referred to the German Paediatric Pain Centre over a 5-year period. Methods Demographic variables, pain characteristics and psychometric measures were assessed at the first evaluation. Subgroup analysis for sex, age and pain location was conducted and multivariate logistic regression applied to identify parameters associated with extremely high impairment. Results The retrospective study consisted of 2249 children assessed at the first evaluation. Tension type headache (48%), migraine (43%) and functional abdominal pain (11%) were the most common diagnoses with a high rate of co-occurrence; 18% had some form of musculoskeletal pain disease. Irrespective of pain location, chronic pain disorder with somatic and psychological factors was diagnosed frequently (43%). 55% of the children suffered from more than one distinct pain diagnosis. Clinically significant depression and general anxiety scores were expressed by 24% and 19% of the patients, respectively. Girls over the age of 13 were more likely to seek tertiary treatment compared to boys. Nearly half of children suffered from daily or constant pain with a mean pain value of 6/10. Extremely high pain-related impairment, operationalized as a comprehensive measure of pain duration, frequency, intensity, pain-related school absence and disability, was associated with older age, multiple locations of pain, increased depression and prior hospital stays. 43% of the children taking analgesics had no indication for pharmacological treatment. Conclusion Children with chronic pain are a diagnostic and therapeutic challenge as they often have two or more different pain diagnoses, are prone to misuse of analgesics and are severely

  5. Characteristics of highly impaired children with severe chronic pain: a 5-year retrospective study on 2249 pediatric pain patients.

    PubMed

    Zernikow, Boris; Wager, Julia; Hechler, Tanja; Hasan, Carola; Rohr, Uta; Dobe, Michael; Meyer, Adrian; Hübner-Möhler, Bettina; Wamsler, Christine; Blankenburg, Markus

    2012-05-16

    Prevalence of pain as a recurrent symptom in children is known to be high, but little is known about children with high impairment from chronic pain seeking specialized treatment. The purpose of this study was the precise description of children with high impairment from chronic pain referred to the German Paediatric Pain Centre over a 5-year period. Demographic variables, pain characteristics and psychometric measures were assessed at the first evaluation. Subgroup analysis for sex, age and pain location was conducted and multivariate logistic regression applied to identify parameters associated with extremely high impairment. The retrospective study consisted of 2249 children assessed at the first evaluation. Tension type headache (48%), migraine (43%) and functional abdominal pain (11%) were the most common diagnoses with a high rate of co-occurrence; 18% had some form of musculoskeletal pain disease. Irrespective of pain location, chronic pain disorder with somatic and psychological factors was diagnosed frequently (43%). 55% of the children suffered from more than one distinct pain diagnosis. Clinically significant depression and general anxiety scores were expressed by 24% and 19% of the patients, respectively. Girls over the age of 13 were more likely to seek tertiary treatment compared to boys. Nearly half of children suffered from daily or constant pain with a mean pain value of 6/10. Extremely high pain-related impairment, operationalized as a comprehensive measure of pain duration, frequency, intensity, pain-related school absence and disability, was associated with older age, multiple locations of pain, increased depression and prior hospital stays. 43% of the children taking analgesics had no indication for pharmacological treatment. Children with chronic pain are a diagnostic and therapeutic challenge as they often have two or more different pain diagnoses, are prone to misuse of analgesics and are severely impaired. They are at increased risk for

  6. Hypnosis for reduction of background pain and pain anxiety in men with burns: A blinded, randomised, placebo-controlled study.

    PubMed

    Jafarizadeh, Hossein; Lotfi, Mojgan; Ajoudani, Fardin; Kiani, Arezou; Alinejad, Vahid

    2017-08-08

    'Background pain' and 'pain anxiety' are among the numerous problems of patients with burns. Non-pharmacological and pharmacological interventions have been used to reduce background pain and pain anxiety. This study compared the effectiveness of hypnosis and 'neutral hypnosis' (as a placebo in the control group) in decreasing the background burn pain and pain anxiety of adult male survivors with burns. This is a blinded, randomised, placebo-controlled study. Sixty men with burns were included in the minimisation method (30 individuals in the intervention group and 30 individuals in the control group). Four hypnotherapy sessions were performed every other day for each participant in the intervention group. Four neutral hypnosis sessions were performed every other day in the control group. Burn pain and pain anxiety of the patients in both groups were measured at the end of the second and fourth sessions. Repeated measures ANOVA was used for data analysis. There was no significant difference between the groups in the reduction in background pain intensity. There was a significant reduction in background pain quality and pain anxiety in the intervention group during the four hypnosis sessions. After two hypnotherapy sessions, a significant reduction was observed in the level of background pain quality and pain anxiety of participants. Hypnosis is effective in reducing background pain quality and pain anxiety of men with burns. Copyright © 2017 Elsevier Ltd and ISBI. All rights reserved.

  7. Retrospective study to identify trigeminal-cervical ocular referred pain as a new causative entity of ocular pain.

    PubMed

    Tseng, Scheffer Cg; Cheng, Anny Ms; Fu, Yao

    2017-01-01

    To determine the prevalence and clinical characteristics of trigeminal-cervical (TC) ocular referred pain. A retrospective study of 1,680 patients seen during 2002-2010 was performed in an ocular surface specialty center to identify patients with or without TC pain defined as ocular pain with ipsilateral trigger points located at the occipital region. Patients with refractory TC pain despite topical anesthetics and conventional treatments received interventional injection to each trigger point. A total of 81 (4.8%) patients (study group) with TC pain and 241 patients (control group) without TC pain were identified out of the 1,680 patients over an 8 year period. There was no difference in age, gender, prior surgeries, medications, non-pain symptoms, pain laterality, and concomitant ocular diseases between the 2 groups. Multivariate regression analysis showed that patients with TC pain had a significant correlation with persistent deep ocular pain, ipsilateral trigger points (f(2)=99, p<0.001) but not headaches (f(2)=0.09, p=0.5). Injection at the trigger points achieved complete or partial pain resolution with a low recurrence rate in 43 of 45 (96%) patients with TC pain. TC pain defined herein may be a different entity of ocular pain and can indeed be differentiated from other ocular pain by the referral character so that one may avoid mislabeling it as undetermined or as a reason to unnecessarily overtreat concomitant ocular diseases.

  8. Retrospective study to identify trigeminal–cervical ocular referred pain as a new causative entity of ocular pain

    PubMed Central

    Tseng, Scheffer CG; Cheng, Anny MS; Fu, Yao

    2017-01-01

    Purpose To determine the prevalence and clinical characteristics of trigeminal–cervical (TC) ocular referred pain. Methods A retrospective study of 1,680 patients seen during 2002–2010 was performed in an ocular surface specialty center to identify patients with or without TC pain defined as ocular pain with ipsilateral trigger points located at the occipital region. Patients with refractory TC pain despite topical anesthetics and conventional treatments received interventional injection to each trigger point. Results A total of 81 (4.8%) patients (study group) with TC pain and 241 patients (control group) without TC pain were identified out of the 1,680 patients over an 8 year period. There was no difference in age, gender, prior surgeries, medications, non-pain symptoms, pain laterality, and concomitant ocular diseases between the 2 groups. Multivariate regression analysis showed that patients with TC pain had a significant correlation with persistent deep ocular pain, ipsilateral trigger points (f2=99, p<0.001) but not headaches (f2=0.09, p=0.5). Injection at the trigger points achieved complete or partial pain resolution with a low recurrence rate in 43 of 45 (96%) patients with TC pain. Conclusion TC pain defined herein may be a different entity of ocular pain and can indeed be differentiated from other ocular pain by the referral character so that one may avoid mislabeling it as undetermined or as a reason to unnecessarily overtreat concomitant ocular diseases. PMID:28794654

  9. Child attention to pain and pain tolerance are dependent upon anxiety and attention control: An eye-tracking study.

    PubMed

    Heathcote, L C; Lau, J Y F; Mueller, S C; Eccleston, C; Fox, E; Bosmans, M; Vervoort, T

    2017-02-01

    Pain is common and can be debilitating in childhood. Theoretical models propose that attention to pain plays a key role in pain outcomes, however, very little research has investigated this in youth. This study examined how anxiety-related variables and attention control interacted to predict children's attention to pain cues using eye-tracking methodology, and their pain tolerance on the cold pressor test (CPT). Children aged 8-17 years had their eye-gaze tracked whilst they viewed photographs of other children displaying painful facial expressions during the CPT, before completing the CPT themselves. Children also completed self-report measures of anxiety and attention control. Findings indicated that anxiety and attention control did not impact children's initial fixations on pain or neutral faces, but did impact how long they dwelled on pain versus neutral faces. For children reporting low levels of attention control, higher anxiety was associated with less dwell time on pain faces as opposed to neutral faces, and the opposite pattern was observed for children with high attention control. Anxiety and attention control also interacted to predict pain outcomes. For children with low attention control, increasing anxiety was associated with anticipating more pain and tolerating pain for less time. This is the first study to examine children's attention to pain cues using eye-tracking technology in the context of a salient painful experience. Data suggest that attention control is an important moderator of anxiety on multiple outcomes relevant to young people's pain experiences. This study uses eye tracking to study attention to pain cues in children. Attention control is an important moderator of anxiety on attention bias to pain and tolerance of cold pressor pain in youth. © 2016 European Pain Federation - EFIC®.

  10. Efficacy and safety of PPC-5650 on experimental rectal pain in patients with irritable bowel syndrome.

    PubMed

    Nielsen, Lecia Møller; Olesen, Anne Estrup; Andresen, Trine; Simrén, Magnus; Törnblom, Hans; Drewes, Asbjørn Mohr

    2015-02-01

    PPC-5650 is a new pharmacological agent that can modulate acid-sensing ion channel activity, leading to a reduction in the pain signal under up-regulated conditions. The non-clinical programme for PPC-5650 supported a role for this novel agent in the treatment of pain in patients with irritable bowel syndrome (IBS). In patients with IBS, the aims of the study were: (1) to assess the efficacy of a single bolus of PPC-5650 locally applied in the rectum using multi-modal stimulations of the recto sigmoid and (2) to assess the safety profile of PPC-5650. The study was a randomized, double-blind, placebo-controlled, cross-over trial in patients with IBS, excluding females of child-bearing potential. The study consisted of a training visit, study visit 1 and 2 and a follow-up visit. Rectosigmoid electrical, thermal and mechanical stimulations were performed, pain perception was rated on a pain intensity scale and referred pain areas were assessed. All adverse events were registered. Twenty-five patients with IBS were enrolled and completed the study (9 women and 16 men; mean age 50.4 ± 12.7 years). No effects of the study drug were found on any of the rectal stimulations or for referred pain areas (all p > 0.05). No significant or clinically relevant treatment-related differences were seen for the laboratory safety variables or any other reported adverse event. In conclusion, in patients with IBS on rectal sensitivity to multi-modal stimulations, PPC-5650 did not produce efficacy relative to placebo. The overall safety and tolerability of PPC-5650 was acceptable.

  11. A pilot study investigating the effects of fast left prefrontal rTMS on chronic neuropathic pain

    PubMed Central

    Borckardt, Jeffrey J.; Smith, Arthur R.; Reeves, Scott T.; Madan, Alok; Shelley, Neal; Branham, Richard; Nahas, Ziad; George, Mark S.

    2010-01-01

    Objective Stimulating the human cortex using transcranial magnetic stimulation (TMS) temporarily reduces clinical and experimental pain, however, it is unclear which cortical targets are the most effective. The motor cortex has been a popular target for managing neuropathic pain, while the prefrontal cortex has been investigated for an array of nociceptive pain conditions. It is unclear whether the motor cortex is the only effective cortical target for managing neuropathic pain, and no published studies to date have investigated the effects of prefrontal stimulation on neuropathic pain. Design This preliminary pilot trial employed a sham-controlled, within-subject, cross-over design to evaluate clinical pain as well as laboratory pain thresholds among four patients with chronic neuropathic pain. Each participant underwent three real and three sham 20-minute sessions of 10Hz left prefrontal rTMS. Daily pain diaries were collected for 3-weeks before and after each treatment phase along with a battery of self-report pain and mood questionnaires. Results Time-series analysis at the individual patient level indicated that real TMS was associated with significant improvements in average daily pain in 3 of the 4 participants. These effects were independent of changes in mood in 2 of the participants. At the group level, a decrease of 19% in daily pain on average, pain at its worst, and pain at its least was observed while controlling for changes in mood, activity-level and sleep. The effects of real TMS were significantly greater than sham. Real TMS was associated with increases in thermal and mechanical pain thresholds whereas sham was not. No statistically significant effects were observed across the questionnaire data. Conclusions The prefrontal cortex may be an important TMS cortical target for managing certain types of pain, including certain neuropathic pain syndromes. PMID:19594842

  12. A Clinical Experimental Model to Evaluate Analgesic Effect of Remote Ischemic Preconditioning in Acute Postoperative Pain

    PubMed Central

    Pereira, Francisco Elano Carvalho; Mello, Irene Lopes; Pimenta, Fernando Heladio de Oliveira Medeiros; Costa, Debora Maia; Wong, Deysi Viviana Tenazoa; Fernandes, Claudia Regina; Lima Junior, Roberto César; Gomes, Josenília M. Alves

    2016-01-01

    This study aims to evaluate the viability of a clinical model of remote ischemic preconditioning (RIPC) and its analgesic effects. It is a prospective study with twenty (20) patients randomly divided into two groups: control group and RIPC group. The opioid analgesics consumption in the postoperative period, the presence of secondary mechanical hyperalgesia, the scores of postoperative pain by visual analog scale, and the plasma levels interleukins (IL-6) were evaluated. The tourniquet applying after spinal anesthetic block was safe, producing no pain for all patients in the tourniquet group. The total dose of morphine consumption in 24 hours was significantly lower in RIPC group than in the control group (p = 0.0156). The intensity analysis of rest pain, pain during coughing and pain in deep breathing, showed that visual analogue scale (VAS) scores were significantly lower in RIPC group compared to the control group: p = 0.0087, 0.0119, and 0.0015, respectively. There were no differences between groups in the analysis of presence or absence of mechanical hyperalgesia (p = 0.0704) and in the serum levels of IL-6 dosage over time (p < 0.0001). This clinical model of remote ischemic preconditioning promoted satisfactory analgesia in patients undergoing conventional cholecystectomy, without changing serum levels of IL-6. PMID:27446611

  13. Toll-like Receptor 4 and Comorbid Pain in Interstitial Cystitis/Bladder Pain Syndrome: A Multidisciplinary Approach to the Study of Chronic Pelvic Pain Research Network Study

    PubMed Central

    Schrepf, Andrew; Bradley, Catherine S.; O'Donnell, Michael; Luo, Yi; Harte, Steven E.; Kreder, Karl; Lutgendorf, Susan

    2015-01-01

    Background Interstitial Cystitis/Bladder Pain