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Showing papers in "Pain in 2002"


Journal ArticleDOI
01 Feb 2002-Pain
TL;DR: This paper compares the modulatory influences of two principal cognitive variables, attention and emotion, on pain perception and addresses possible neural mechanisms underlying each of these influences.
Abstract: There have been anecdotal accounts for centuries of people apparently experiencing little or no pain in situations that most of us would find excruciating. Yet, western medicine has given little credence to a patient’s ability to modify pain. Instead, we focus on the pharmacological control of pain. For this reason, the vast majority of research on pain control has concentrated on peripheral and spinal cord mechanisms of opioid and anti-inflammatory analgesic therapy. Nevertheless, researchers are beginning to recognize that a variety of pain modulatory mechanisms exist in the nervous system, and these modulatory systems can be accessed either pharmacologically or through contextual and/or cognitive manipulation (Fields, 2000). Variables such as attentional state, emotional context, hypnotic suggestions, attitudes, expectations or anesthesia-induced changes in consciousness now have been shown to alter both pain perception and forebrain pain transmission in humans. These techniques, at times, preferentially alter sensory and/or affective aspects of pain perception, and the associated modulation of pain-evoked neural activity occurs in limbic and/or sensory brain regions, suggesting multiple endogenous pain-modulatory systems. This paper compares the modulatory influences of two principal cognitive variables, attention and emotion, on pain perception and addresses possible neural mechanisms underlying each of these influences.

611 citations


Journal ArticleDOI
01 Apr 2002-Pain
TL;DR: It was found that this model could be considered as invariant across three samples (pain‐free students, chronic low back pain patients, and fibromyalgia patients) and across gender, indicating that the same processes are measured in different subgroups.
Abstract: This study examined the factor structure of the Pain Catastrophizing Scale in three different Dutch-speaking samples: 550 pain-free students, 162 chronic low back pain patients, and 100 fibromyalgia patients. Confirmatory factor analyses were used to compare three different models of pain catastrophizing (one factor, two oblique factors, three oblique factors), and to investigate the invariance of the factor structure across the three different samples. The results indicated that a three-factor oblique model with a four-item rumination factor, a three-item magnification factor, and a six-item helplessness factor provided the best fit to the data in the three samples. Furthermore, it was found that this model could be considered as invariant across three samples (pain-free students, chronic low back pain patients, and fibromyalgia patients) and across gender, indicating that the same processes are measured in different subgroups.

509 citations


Journal ArticleDOI
01 Jan 2002-Pain
TL;DR: It is shown that intrathecal administration of specific antisense oligodeoxynucleotides (ODN) to the peripheral tetrodotoxin (TTX)‐resistant sodium channel, NaV1.8, resulted in a time‐dependent uptake of the ODN by dorsal root ganglion (DRG) neurons, and a selective ‘knock‐down’ of the expression of NaV 1.8 which reversed neuropathic pain induced by spinal nerve injury.
Abstract: Neuropathic pain is a debilitating chronic syndrome that often arises from injuries to peripheral nerves. Such pain has been hypothesized to be the result of an aberrant expression and function of sodium channels at the site of injury. Here, we show that intrathecal administration of specific antisense oligodeoxynucleotides (ODN) to the peripheral tetrodotoxin (TTX)-resistant sodium channel, NaV1.8, resulted in a time-dependent uptake of the ODN by dorsal root ganglion (DRG) neurons, a selective "knock-down" of the expression of NaV1.8, and a reduction in the slow-inactivating, TTX-resistant sodium current in the DRG cells. The ODN treatment also reversed neuropathic pain induced by spinal nerve injury, without affecting non-noxious sensation or response to acute pain. These data provide direct evidence linking NaV1.8 to neuropathic pain. As NaV1.8 expression is restricted to sensory neurons, this channel offers a highly specific and effective molecular target for the treatment of neuropathic pain.

452 citations


Journal ArticleDOI
Jianren Mao1
01 Dec 2002-Pain
TL;DR: The current evidence suggests that opioid-induced pain sensitivity may be preventable by interrupting the cellular and molecular changes associated with the development of opioid tolerance, and these issues will be discussed in the article with the emphasis on their clinical implications.
Abstract: Opioids produce analgesic effects through their modulatory role in nociceptive transmission. Under many circumstances opioids are the most efficacious analgesics commonly used in the clinical management of moderate to severe pain. Besides the known side effects, opioid treatment is associated with the development of tolerance to and dependence on opioid analgesics. A notable feature of opioid dependence is that hyperalgesic responses may occur both in animals and human subjects during a precipitated opioid withdrawal. This observation suggests that a pronociceptive process may have developed during opioid treatment, which may be unmasked following an opioid withdrawal. Over the last several years, compelling evidence has accumulated indicating that abnormal pain sensitivity including hyperalgesia and allodynia occurs in animals receiving opioid administration even in the absence of overt, precipitated opioid withdrawal. This paradoxical opioid-induced pain sensitivity may be contributory to the behavioral manifestation of apparent opioid tolerance, a need for a dose increase to maintain the same analgesic efficacy. Similar changes in pain sensitivity have been observed in pain patients with opioid therapy and in former opioid addicts maintained on methadone treatment. Moreover, a growing body of evidence suggests that the development of opioid-induced pain sensitivity is mediated through neural mechanisms that involve cellular changes and neural circuits and that interact with the mechanisms underlying the development of pathological pain. The current evidence also suggests that opioid-induced pain sensitivity may be preventable by interrupting the cellular and molecular changes associated with the development of opioid tolerance. These issues will be discussed in the article with the emphasis on their clinical implications. 2. Preclinical evidence of opioid-induced pain sensitivity

438 citations


Journal ArticleDOI
01 Nov 2002-Pain
TL;DR: This review will discuss recent conceptual advances in the understanding of descending modulation and its role in persistent pain, and the existence of bidirectional descending control, and molecular mechanisms of activity-dependent plasticity in descending modulatory circuitry.
Abstract: Our knowledge of the existence of endogenous descending pain modulatory systems spans at least three decades and we now know that brain stem descending pathways constitute a major mechanism in the control of pain transmission (for comprehensive reviews, see Fields and Basbaum, 1999; Millan, 2002). The basis for an endogenous descending pain modulatory circuit linking the periaqueductal gray (PAG), the rostral ventromedial medulla (RVM) and the spinal cord, has now been well established (Gebhart, 1986; Fields et al., 1991; Fields and Basbaum, 1999; Millan, 2002 for reviews). Recent studies indicate that hyperalgesia in animal models of inflammatory and neuropathic pain is closely linked to activation of descending modulatory circuits involving both inhibition and facilitation. This review will discuss recent conceptual advances in our understanding of descending modulation and its role in persistent pain. The following issues will be described below: (1) the existence of bidirectional descending control; (2) descending modulatory influences after tissue and nerve injury; (3) dynamic shifts in descending modulation after injury; and (4) molecular mechanisms of activity-dependent plasticity in descending modulatory circuitry. The clinical implications of the findings will then be discussed.

421 citations


Journal ArticleDOI
01 Mar 2002-Pain
TL;DR: In this paper, the authors evaluated the effectiveness of corticosteroid injections in the treatment of lateral epicondylitis (tennis elbow) by systematic review of the available randomized clinical trials.
Abstract: BACKGROUND: Lateral epicondylitis (tennis elbow) is a common complaint, for which corticosteroid injections are a frequently applied therapy. However, there were no up-to-date reviews available that systematically addressed the effectiveness and adverse effects, including questions concerning optimal timing of injections and composition of the injection fluid. AIM: The aim of the study was to assess the effectiveness of corticosteroid injections in the treatment of lateral epicondylitis (tennis elbow) by systematic review of the available randomized clinical trials. DATA SOURCES: The data sources used were randomized clinical trials identified by literature searches of the MedLine (1966-1994) and Embase (Exerpta Medica) (1980-1994) databases for the keywords epicondylitis, tendinitis and elbow, injection. References given in relevant publications were further examined. STUDY SELECTION: The criteria for selecting studies were as follows: randomized clinical trials (treatment allocation in random or alternate order); one of the treatments to include one or more corticosteroid injections (additional interventions were allowed); participants suffering from lateral epicondylitis; and publication in English, German or Dutch. Abstracts and unpublished studies were not included. DATA SYNTHESIS: Methodological quality was assessed by means of a standardized criteria list (range 1-100 points). The extracted outcomes were the general conclusion drawn by the authors of the reports on the trials, and the success rates at the various follow-up points as (re)calculated by us. The success rates were subsequently graphically displayed and statistically pooled. Separate stratified analyses were conducted according to a predetermined analysis plan. RESULTS: Twelve randomized clinical trials were identified. The median methodological score was 40 points, indicating an overall poor to moderate quality. The pooled analysis indicated short-term effectiveness (2-6 weeks): pooled odds ratio (OR) = 0.15 [95% confidence interval (CI) 0.10-0.23], chi 2 [degrees of freedom (df = 5) = 13.3], indicating statistical heterogeneity. At longer term follow-up, no difference could be detected. The studies of better methodological quality indicated more favourable results than those of lesser methodological quality. The most suitable corticosteroid to use as well as dosage, injection interval and injection volume could not be derived from the various trials. CONCLUSION: The existing evidence on corticosteroid injections for the treatment of tennis elbow is not conclusive. Many trials were conducted in a secondary care setting and clearly had serious methodological flaws, and there was statistical heterogeneity among the trials. Corticosteroid injections appear to be relatively safe and seem to be effective in the short term (2-6 weeks). Although the treatment seems to be suitable for application in general practice, further trials in this setting are needed. As yet, questions regarding the optimal timing, dosage, injection technique and injection volume remain unanswered.

401 citations


Journal ArticleDOI
01 Oct 2002-Pain
TL;DR: It is suggested that placebo analgesic effects are most optimally conceptualized in terms of perception of the placebo agent, and therefore a new definition of placebo response is proposed.
Abstract: A previous meta-analysis of clinical analgesic trial studies showed generally low magnitudes of placebo analgesia (N Engl J Med 344 (2001) 1594) However, as studies included in their analysis used only placebo as a control condition, we conducted two meta-analyses, one in which 23 studies used only placebo as a control condition, and one in which 14 studies investigated placebo analgesic mechanisms Magnitudes of placebo analgesic effects were much higher in the latter (mean effect size=095) as compared to the former (mean effect size=015) and were significantly different (P=0003) This difference as well as differences in effect sizes within studies of placebo mechanisms may be parsimoniously explained by differences in expected pain levels produced by placebo suggestions and by conditioning Furthermore, some of the studies of placebo analgesic mechanisms indicate that the magnitude of placebo analgesia is higher when the placebo analgesic effect is induced via suggestion combined with conditioning than via suggestion alone or conditioning alone Based on these findings, we suggest that placebo analgesic effects are most optimally conceptualized in terms of perception of the placebo agent, and therefore a new definition of placebo response is proposed

399 citations


Journal ArticleDOI
01 Oct 2002-Pain
TL;DR: This study shows that gabapentin reduces pain and improves some quality‐of‐life measures in patients with a wide range of neuropathic pain syndromes.
Abstract: A double-blind, randomised, placebo-controlled 8-week study was conducted to evaluate the efficacy and safety of gabapentin in the treatment of neuropathic pain, using doses up to 2400 mg/day. The study used a novel design that was symptom- rather than syndrome-based; an approach that aimed to reflect the realities of clinical practice. Participants had a wide range of neuropathic pain syndromes, with at least two of the following symptoms: allodynia, burning pain, shooting pain, or hyperalgesia. Patients were randomised to gabapentin (n=153) or placebo (n=152). Gabapentin was given in three divided doses, initially titrated to 900 mg/day over 3 days, followed by two further increases, to a maximum of 2400 mg/day if required by the end of week 5. The primary outcome measure was changed in average daily pain diary score (baseline versus final week). Over the 8 week study, this score decreased (i.e. improved) by 1.5 (21%) in gabapentin treated patients and by 1.0 (14%) in placebo treated patients (P=0.048, rank-based analysis of covariance). Significant differences were shown in favour of gabapentin (P<0.05) for the Clinician and Patient Global Impression of Change, and some domains of the Short Form-McGill Pain Questionnaire. Improvements were also shown in patient-reported outcomes in quality of life, as seen by significant differences in favour of gabapentin in several domains of the Short-Form-36 Health Survey. Gabapentin was well tolerated and the majority of patients completed the study (79 versus 73% for placebo). The most common adverse events were mild to moderate dizziness and somnolence, most of which were transient and occurred during the titration phase. This study shows that gabapentin reduces pain and improves some quality-of-life measures in patients with a wide range of neuropathic pain syndromes.

393 citations


Journal ArticleDOI
01 Sep 2002-Pain
TL;DR: Chronic pain is a common, persistent problem in the community with relatively high incidence and low recovery rates, and the lack of association between onset or recovery from chronic pain and most traditional socio‐demographic factors highlights the need to broaden the range of factors included in studies of chronic pain aetiology.
Abstract: Little is known about the course of chronic pain in the community. Such information is needed for the prevention and management of chronic pain. We undertook a 4-year follow-up study of 2184 individuals living in Grampian, UK to describe patterns and predictors of change in chronic pain over time. In October 2000, participants completed a postal questionnaire including case definition questions, the chronic pain grade questionnaire, the SF-36 and socio-demographic questions. Information from this questionnaire was compared to information collected from a similar questionnaire in 1996. A response rate of 83% was achieved for the follow-up study. The overall prevalence of chronic pain (pain or discomfort present either all the time or on and off for 3 months or longer) increased from 45.5% at baseline to 53.8% at follow-up. Seventy-nine percent of those with chronic pain at baseline still had it at follow-up. The average annual incidence was 8.3% and the average annual recovery rate was 5.4%. Individuals in the study samples who are in lowest quartile of SF-36 domains--physical functioning, social functioning and bodily pain at baseline--were more likely to develop chronic pain at follow-up, and respondents who were retired were less likely to develop chronic pain. Individuals in the study samples in the lowest quartile of SF-36 domains, bodily pain and general health at baseline, were less likely to recover from their chronic pain, as were those aged 45-74 compared with those aged 25-34. We concluded that chronic pain is a common, persistent problem in the community with relatively high incidence and low recovery rates. The lack of association between onset or recovery from chronic pain and most traditional socio-demographic factors, highlights the need to broaden the range of factors included in studies of chronic pain aetiology.

356 citations


Journal ArticleDOI
01 Aug 2002-Pain
TL;DR: Six patients suffering from complex regional pain syndrome of the upper limb were examined and reactivity of the 20‐Hz motor cortex rhythm to tactile stimuli was altered in the CRPS patients, suggesting modified inhibition of the motor cortex.
Abstract: Alterations in tactile sensitivity are common in patients with chronic pain. Recent brain imaging studies have indicated that brain areas activated by acute experimental pain partly overlap with areas processing innocuous tactile stimuli. However, the possible effect of chronic pain on central tactile processing has remained unclear. We have examined, both clinically and with whole-head magnetoencephalography, six patients suffering from complex regional pain syndrome (CRPS) of the upper limb. The cortical somatosensory responses were elicited by tactile stimuli applied to the fingertips and the reactivity of spontaneous brain oscillations was monitored as well. Tactile stimulation of the index finger elicited an initial activation at 65 ms in the contralateral SI cortex, followed by activation of the ipsi- and contralateral SII cortices at about 130 ms. The SI responses were 25-55% stronger to stimulation of the painful than the healthy side. The distance between SI representations of thumb and little finger was significantly shorter in the hemisphere contralateral than ipsilateral to the painful upper limb. In addition, reactivity of the 20-Hz motor cortex rhythm to tactile stimuli was altered in the CRPS patients, suggesting modified inhibition of the motor cortex. These results imply that chronic pain may alter central tactile and motor processing.

351 citations


Journal ArticleDOI
01 May 2002-Pain
TL;DR: The aim of this study was to determine the prevalence and important symptom characteristics of low back pain such as duration, periodicity, intensity, disability and health seeking behaviour at young ages in the North‐West of England.
Abstract: Low back pain in adolescents is perceived to be uncommon in the clinic setting. However, previous studies have suggested that it may be an important and increasing problem in this age-group. The aim of this study was to determine the prevalence and important symptom characteristics of low back pain such as duration, periodicity, intensity, disability and health seeking behaviour at young ages. A population-based cross-sectional study was conducted including 1446 children aged 11-14 years in the North-West of England. A self-complete questionnaire was used to assess low back pain prevalence, symptom characteristics, associated disability and health seeking behaviour. An additional self-complete questionnaire amongst parents sought to validate pain reporting. The 1-month period prevalence of low back pain was 24%. It was higher in girls than boys (29 vs. 19%; 2=14.7, P<0.001) and increased with age in both sexes (P<0.001). Of those reporting low back pain, 94% experienced some disability, with the most common reports being of difficulty carrying school bags. Despite this high rate of disability, few sought medical attention. Adolescent low back pain is common although medical attention is rarely sought. Such symptoms in childhood, particularly as they are so common, may have important consequences for chronic low back pain in adulthood.

Journal ArticleDOI
01 Sep 2002-Pain
TL;DR: The results indirectly suggest that temporal summation of second pain (windup) contributes to processes underlying hyperalgesia and persistent pain states, and these processes can be centrally modulated in FMS patients by endogenous and exogenous analgesic manipulations.
Abstract: We have previously shown that fibromyalgia (FMS) patients have enhanced temporal summation (windup) and prolonged decay of heat-induced second pain in comparison to control subjects, consistent with central sensitization. It has been hypothesized that sensory abnormalities of FMS patients are related to deficient pain modulatory mechanisms. Therefore, we conducted several analyses to further characterize enhanced windup in FMS patients and to determine whether it can be centrally modulated by placebo, naloxone, or fentanyl. Pre-drug baseline ratings of FMS and normal control (NC) groups were compared with determine whether FMS had higher pain sensitivity in response to several types of thermal tests used to predominantly activate A-delta heat, C heat, or cold nociceptors. Our results confirmed and extended our earlier study in showing that FMS patients had larger magnitudes of heat tap as well as cold tap-induced windup when compared with age- and sex-matched NC subjects. The groups differed less in their ratings of sensory tests that rely predominantly on A-delta-nociceptive afferent input. Heat and cold-induced windup were attenuated by saline placebo injections and by fentanyl (0.75 and 1.5 microg/kg). However, naloxone injection had the same magnitudes of effect on first or second pain as that produced by placebo injection. Hypoalgesic effects of saline placebo and fentanyl on windup were at least as large in FMS as compared to NC subjects and therefore do not support the hypothesis that pain modulatory mechanisms are deficient in FMS. To the extent that temporal summation of second pain (windup) contributes to processes underlying hyperalgesia and persistent pain states, these results indirectly suggest that these processes can be centrally modulated in FMS patients by endogenous and exogenous analgesic manipulations.

Journal ArticleDOI
01 Jul 2002-Pain
TL;DR: Catastrophizing, but not any other single pain coping strategy, was consistently strongly and independently associated with the outcome measures and potentially, the assessment and treatment of catastrophizing may reduce psychological distress and pain‐related disability among individuals with chronic pain and SCI.
Abstract: Little research has examined the role of patient cognitive and behavioral responses, including catastrophizing, in adjustment to chronic pain associated with spinal cord injury (SCI). The objective of this study was to examine the associations of catastrophizing and specific pain coping strategies with pain intensity, psychological distress, and pain-related disability among individuals with chronic pain and SCI, after controlling for important demographic and SCI-related variables that might affect outcomes. Participants in this study were 174 community residents with SCI and chronic pain who completed a mailed questionnaire that included the SF-36 Mental Health scale, Coping Strategies Questionnaire, and Graded Chronic Pain Scale. The pain coping and catastrophizing measures explained an additional 29% of the variance in pain intensity after adjusting for the demographic and SCI variables (P<0.001). The coping and catastrophizing scales accounted for an additional 30% of the variance in psychological distress (P<0.001) and 11% of the variance in pain-related disability (P<0.001), after controlling for pain intensity and demographic and SCI variables. Catastrophizing, but not any other single pain coping strategy, was consistently strongly and independently associated with the outcome measures. Potentially, the assessment and treatment of catastrophizing may reduce psychological distress and pain-related disability among individuals with chronic pain and SCI.

Journal ArticleDOI
01 Apr 2002-Pain
TL;DR: It appears that GREP do play a part in determining an individual's pain report and may be contributing to the sex differences in the laboratory setting.
Abstract: The primary purpose of this study was to investigate the influence of an individual's Gender Role Expectations of Pain (GREP) on experimental pain report. One hundred and forty-eight subjects (87 females and 61 males) subjects underwent thermal testing and were asked to report pain threshold, pain tolerance, VAS ratings of pain intensity and unpleasantness, and a computerized visual analogue scales (VAS) rating of pain intensity during the procedure. Subjects completed the GREP questionnaire to assess sex-related stereotypic attributions of pain sensitivity, pain endurance, and willingness to report pain. Consistent with previous research, significant sex differences emerged for measures of pain threshold, pain tolerance, and pain unpleasantness. After statistically controlling for age, GREP scores were significant predictors of threshold, tolerance, and pain unpleasantness, accounting for an additional 7, 11, and 21% of the variance, respectively. Sex remained a significant predictor of pain tolerance in hierarchical regression analyses after controlling for GREP scores. Results provide support for two competing but not mutually exclusive hypotheses related to the sex differences in experimental pain. Both psychosocial factors and first-order, biological sex differences remain as viable explanations for differences in experimental pain report between the sexes. It appears that GREP do play a part in determining an individual's pain report and may be contributing to the sex differences in the laboratory setting.

Journal ArticleDOI
01 Mar 2002-Pain
TL;DR: The induction of bone cancer in the rat by the syngeneic MRMT‐1 mammary tumour cell line provides a valid pre‐clinical model for pain associated with bone metastases and suggests a reasonable time window for evaluation of anti‐nociceptive agents between day 14 and 20 after cancer cell inoculation in this model.
Abstract: This study describes the first known model of bone cancer pain in the rat Sprague-Dawley rats receiving intra-tibial injections of syngeneic MRMT-1 rat mammary gland carcinoma cells developed behavioural signs indicative of pain, including: mechanical allodynia, difference of weight bearing between hind paws and mechanical hyperalgesia The development of the bone tumour and structural damage to the bone was monitored by radiological analysis, quantitative measurement of mineral content and histology Intra-tibial injections of 3 x 10(3) or 3 x 10(4) syngeneic MRMT-1 cells produced a rapidly expanding tumour within the boundaries of the tibia, causing severe remodelling of the bone Radiographs showed extensive damage to the cortical bone and the trabeculae by day 10-14 after inoculation of 3 x 10(3) MRMT-1 cells, and by day 20, the damage was threatening the integrity of the tibial bone While both mineral content and mineral density decreased significantly in the cancerous bone, osteoclast numbers in the peritumoural compact bone remained unchanged However, tartarate-resistant acid phosphatase staining revealed a large number of polykariotic cells, resembling those of osteoclasts within the tumour No tumour growth was observed after the injection of heat-killed MRMT-1 cells Intra-tibial injections of 3 x 10(3) or 3 x 10(4) MRMT-1 cells, heat-killed cells or vehicle did not show changes in body weight and core temperature over 19-20 days The general activity of animals after injection with live or heat-killed MRMT-1 cells was higher than that of the control group, however, the activity of the MRMT-1 treated group declined during the progress of the disease Rats receiving intra-tibial injections of MRMT-1 cells displayed the gradual development of mechanical allodynia and mechanical hyperalgesia/reduced weight bearing on the affected limb, beginning on day 12-14 or 10-12 following injection of 3 x 10(3) or 3 x 10(4) cells, respectively These symptoms were not observed in rats receiving heat-killed cells or vehicle Behavioural data suggest a reasonable time window for evaluation of anti-nociceptive agents between day 14 and 20 after cancer cell inoculation in this model Acute treatment with morphine (1-3mg/kg, subcutanously (sc)) produced a dose-dependent reduction in the response frequency of hind paw withdrawal to von Frey filament stimulation 17 or 19 days following intra-tibial injections of 3 x 10(3) MRMT-1 cells A significant reduction in the difference in hind limb weight bearing was also observed Acute treatment with celebrex (10-30 mg/kg, sc) did not affect mechanical allodynia or difference in weight bearing in rats 20 days following treatment with 3 x 10(3) MRMT-1 cells Although the pathophysiology of cancer pain is largely unknown, significant enhancement of glial fibrillary acidic protein (GFAP) staining in the corresponding segments of the ipsilateral spinal cord highlights the possible involvement of astrocytes In summary, the induction of bone cancer in the rat by the syngeneic MRMT-1 mammary tumour cell line provides a valid pre-clinical model for pain associated with bone metastases Significant mechanical hyperalgesia and allodynia develops in association with the progression of the tumour in the bone marrow cavity, while the general condition of the animal remains satisfactory While acute treatment with morphine has some analgesic effect on hind limb sparing the selective COX-2 inhibitor, celebrex, has no influence on the pain-related behavioural changes in this model

Journal ArticleDOI
01 Oct 2002-Pain
TL;DR: The results suggest that fear‐avoidance beliefs and catastrophizing may play an active part in the transition from acute to chronic pain and clinical implications include screening and early intervention.
Abstract: Fear-avoidance beliefs and catastrophizing have been shown to be powerful cognitions in the process of developing chronic pain problems and there is a need for increased knowledge in early stages of pain. The objectives of this study were therefore, firstly, to examine the occurrence of fear-avoidance beliefs and catastrophizing in groups with different degrees of non-chronic spinal pain in a general population, and secondly to assess if fear-avoidance beliefs and catastrophizing were related to current ratings of pain and activities of daily living (ADL). The study was a part of a population based back pain project and the study sample consisted of 917 men and women, 35-45 years old, either pain-free or with non-chronic spinal pain. The results showed that fear-avoidance beliefs as well as catastrophizing occur in this general population of non-patients. The levels were moderate and in catastrophizing a 'dose-response' pattern was seen, such that more the catastrophizing was, the more was pain. The study showed two relationships, which were between fear-avoidance and ADL as well as between catastrophizing and pain intensity. Logistic regression analyses were performed with 95% confidence intervals and the odds ratio for fear-avoidance beliefs and ADL was 2.5 and for catastrophizing and pain 1.8, both with confidence interval above unity. The results suggest that fear-avoidance beliefs and catastrophizing may play an active part in the transition from acute to chronic pain and clinical implications include screening and early intervention.

Journal ArticleDOI
01 Jan 2002-Pain
TL;DR: This study induced painful perception in patients with phantom-limb pain using hypnotic suggestion that the missing limb was in a painful position and was able to show that when subjects solved the maze task and the authors induced a painful stimulation they perceived less pain as compared with when there was no competition for attentional space.
Abstract: The intensity and unpleasantness of a painful experience is often described as correlating well with the degree of noxious stimulation. However, the perception of pain is not a linear phenomenon, reflecting the signal from the peripheral neuron. Rather, the noxious input may be modulated at every level of the neural axis. One of the most potent sources of modulation is the brain—although these mechanisms have only sparsely been studied. The supraspinal modulatory influences involve both lower order automatic response schemata and higher order dynamic cognitive mechanisms. This organizational pattern has developed as an evolutionary driven adaptation, in which both fast hardwired responses and slower dynamic responses increased the chance for survival. In line with this hypothesis, it has been suggested that the brain is initially processing noxious input in the brainstem supporting the demand for a fast response (Petrovic et al., 2000a; Price, 2000). Apart from autonomic changes and a wide range of defense reactions, the brainstem may induce powerful analgesia in direct response to noxious stimuli (Fanselow, 1994). At a higher level, cognitive processes may dramatically modulate the perception of pain (Melzack and Casey, 1968; Weisenberg et al., 1996). Recently, functional imaging tools, such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI), have described some of the possible underlying mechanisms that are involved in cognitive modulation of pain perception. Several functional imaging studies have indicated that pain processing may be modulated by cognitive mechanisms (Bantick et al., 2001; Longe et al., 2001; Petrovic et al., 2001a,b; Rainville et al., 1997, 1999; Willoch et al., 2000). Rainville and colleagues used hypnotic suggestion to modulate the perception of unpleasantness during noxious stimulation. When the subjects were suggested to perceive the noxious stimulation as highly unpleasant there was a concomitant increase in the activity in the anterior cingulate cortex (ACC) significantly more than when the subjects were suggested to perceive the same stimulation as less unpleasant (Rainville et al., 1997). However, the activity in the somatosensory areas was unaltered. Since lesion studies and animal studies have indicated that the ACC is involved in processing pain unpleasantness (Vogt et al., 1993) this finding indicates that cognitive mechanisms may specifically modulate sub-systems of the pain network. We used a different but classical approach in order to show that pain networks may be modulated by cognitive demands (Petrovic et al., 2000b). Most people have probably experienced that pain perception can decrease and even disappear when actively engaging the mind in a distracting task. We tested this mechanism by involving the subjects in a highly attention demanding task (computerized perceptual maze test) during noxious stimulation. We were able to show that when subjects solved the maze task and we induced a painful stimulation they perceived less pain as compared with when there was no competition for attentional space. At a neural level, activity was significantly attenuated in somatosensory regions and the PAG in this condition. Recently, it has been shown that cognitive distraction also may attenuate the pain-evoked activity in the ACC, the insula and the thalamus (Bantick et al., 2001; Longe et al., 2001). One intriguing study has demonstrated the opposite cognitive modulation in which the pain network was activated without any noxious stimulation being given (Willoch et al., 2000). In this study, painful perception was induced in patients with phantom-limb pain using hypnotic suggestion that the missing limb was in a painful position. All the regions discussed above are involved in pain processing, and modulation in their activity coincides with the changes in a pain perception. Apart from attention dependent changes in the network processing the perception, another distinct set of structures may act as sources for Pain 95 (2002) 1–5

Journal ArticleDOI
01 Sep 2002-Pain
TL;DR: Qualitative sensory tests (QST) in addition to the blink reflex (BR) recordings are used in order to gain further insight into the neural mechanisms of BMS pain.
Abstract: Our preliminary observations on a small group of burning mouth syndrome (BMS) patients indicated a change in the non-nociceptive, tactile sensory function in BMS and provided evidence for the hypothesis of a neuropathic etiology of BMS. In the present clinical study on a group of 52 BMS patients, we used quantitative sensory tests (QST) in addition to the blink reflex (BR) recordings in order to gain further insight into the neural mechanisms of BMS pain. Based on electrophysiologic findings, the BMS patients could be grouped into four different categories: (1) The results of the BR were suggestive of brainstem pathology or peripheral trigeminal neuropathy in ten (19%) patients. In most of the cases, the abnormalities in the BR seemed to represent subclinical changes of the trigeminal system. (2) Increased excitability of the BR was found in the form of deficient habituation of the R2 component of the BR in 11 (21%) of the patients. Two of these patients also showed signs of warm allodynia in QST. (3) One or more of the sensory thresholds were abnormal indicating thin fiber dysfunction in altogether 35 patients (76%) out of the 46 tested with QST. Thirty-three of these patients showed signs of hypoesthesia. (4) There were only five patients with normal findings in both tests. The present findings with strong evidence for neuropathic background in BMS will hopefully provide insights for new therapeutic strategies.

Journal ArticleDOI
01 Oct 2002-Pain
TL;DR: The results indicated that patients with cancer had higher mean scores on the Barriers Questionnaire‐II than did nurses trained in pain management, and the BQ‐II is a reliable and valid measure of patient‐related barriers to cancer pain management.
Abstract: Patients' beliefs can act as barriers to optimal management of cancer pain. The Barriers Questionnaire (BQ) is a tool used to evaluate such barriers. Here, the BQ has been revised to reflect changes in pain management practices, resulting in the Barriers Questionnaire-II (BQ-II), a 27-item, self report instrument. This paper presents the results from two studies where the psychometric properties of the BQ-II were evaluated. In the first study, the responses of 27 nurses trained in pain management were compared to responses of a convenience sample of 12 patients with cancer. The results indicated that patients with cancer had higher mean scores on the BQ-II than did nurses trained in pain management. In the second study, a convenience sample of 172 patients with cancer responded to the BQ-II and a set of pain and quality of life (QOL) measures. A factor analysis supported four factors. Factor one, physiological effects, consists of 12 items addressing the beliefs that side effects of analgesics are inevitable and unmanageable, concerns about tolerance, and concerns about not being able to monitor changes in one's body when taking strong pain medications. Factor two, Fatalism, consists of three items addressing fatalistic beliefs about cancer pain and its management. Factor three, Communication, consists of six items addressing the concern that reports of pain distract the physician from treating the underlying disease, and the belief that 'good' patients do not complain of pain. The fourth and final factor, harmful effects, consists of six items addressing fear of becoming addicted to pain medication and the belief that pain medications harm the immune system. The BQ-II total had an internal consistency of 0.89, and alpha for the subscales ranged from 0.75 to 0.85. Mean (SD) scores on the total scale was 1.52 (0.73). BQ-II scores were related to measures of pain intensity and duration, mood, and QOL. Patients who used adequate analgesics for their levels of pain had lower scores on the BQ-II than did patients who used inadequate analgesics. The BQ-II is a reliable and valid measure of patient-related barriers to cancer pain management.

Journal ArticleDOI
01 Jan 2002-Pain
TL;DR: If cytosol provides a rapid nociceptive signal from damaged tissue, then ATP is a critical messenger and P2X receptors are its sensor, and ion channels that are activated by extracellular ATP are recorded.
Abstract: The release of cytosol from damaged cells has been proposed to be a chemical trigger for nociception. K(+), H(+), adenosine triphosphate (ATP), and glutamate are algogenic agents within cytosol that might contribute to such an effect. To examine which, if any, compounds in cytosol activate ion channels on nociceptors, we recorded currents in dissociated nociceptors when nearby skin cells were damaged. Skin cell damage caused action potential firing and inward currents in nociceptors. Extracts of fibroblast cytosol did the same. Virtually all response to extract and cell killing was eliminated by enzymatic degradation of ATP or desensitization or blockade of P2X receptors, ion channels that are activated by extracellular ATP. Thus, if cytosol provides a rapid nociceptive signal from damaged tissue, then ATP is a critical messenger and P2X receptors are its sensor.

Journal ArticleDOI
01 Jan 2002-Pain
TL;DR: Overall, these results are consistent with limited previous work that argues against three sequential stages of CRPS, but several distinct CRPS subtypes are suggested, and these could ultimately have utility in targeting treatment more effectively.
Abstract: This study tested for evidence supporting the clinical lore of three sequential stages of complex regional pain syndrome (CRPS) and examined the characteristics of possible CRPS subtypes. A series of 113 patients meeting IASP criteria for CRPS underwent standardized history and physical examinations to assess CRPS signs and symptoms in four domains identified in previous research: pain/sensory abnormalities, vasomotor dysfunction, edema/sudomotor dysfunction, and motor/trophic changes. K-Means cluster analysis was used to derive three relatively homogeneous CRPS patient subgroups based on similarity of sign/symptom patterns in these domains. The resulting CRPS subgroups did not differ significantly regarding pain duration as might be expected in a sequential staging model. However, the derived subgroups were statistically-distinct, and suggested three possible CRPS subtypes: (1) a relatively limited syndrome with vasomotor signs predominating, (2) a relatively limited syndrome with neuropathic pain/sensory abnormalities predominating, and (3) a florid CRPS syndrome similar to "classic RSD" descriptions. Subtype 3 showed the highest levels of motor/trophic signs and possible disuse-related changes (osteopenia) on bone scan, despite having directionally the briefest pain duration of the three groups. EMG/NCV testing suggests that Subtype 2 may reflect CRPS-Type 2 (causalgia). Overall, these results are consistent with limited previous work that argues against three sequential stages of CRPS. However, several distinct CRPS subtypes are suggested, and these could ultimately have utility in targeting treatment more effectively.

Journal ArticleDOI
01 Apr 2002-Pain
TL;DR: The ES with a newly developed needle electrode was a very convenient method for the selective stimulation of the A&dgr; fibers, since it was very simple, not requiring any special apparatus, did not cause bleeding or burns and caused minimum uncomfortable feeling.
Abstract: We recorded evoked potentials (EPs) induced by conventional transcutaneous electrical stimulation (TS), laser stimulation (LS) and epidermal electrical stimulation (ES) using a specially made needle electrode. We evaluated the activated fibers by epidermal stimulation by assessing the conduction velocity (CV) of the peripheral nerves. The EPs were recorded from Cz electrode (vertex) of the International 10-20 system in 12 healthy subjects. For the ES, the tip of a stainless steel needle electrode was inserted in the epidermis of the skin (0.2 mm in depth). Distal and proximal sites of the upper limb were stimulated by the LS and ES with an intensity which induced a definite pain sensation. Similar sites were stimulated by TS with an intensity of two times the sensory threshold. A major EP positive response (P1) was obtained by stimulation by all three types of stimuli. The P1 latency for the TS (245+/-22 ms) was significantly shorter than that for the ES (302+/-17 ms, P<0.0001) and LS (341+/-21 ms, P<0.0001) and the peak latency P1 by the LS was also significantly longer, approximately 40 ms, than that by the ES (P<0.0001). The CVs were 15.1, 15.3 and 44.1 m/s obtained by ES, LS and TS, respectively. The CV indicated that the fibers activated by the ES were mainly A fibers, which corresponded to the fibers stimulated by the LS. We considered that the ES with our newly developed needle electrode was a very convenient method for the selective stimulation of the A fibers, since it was very simple, not requiring any special apparatus, did not cause bleeding or burns and caused minimum uncomfortable feeling.

Journal ArticleDOI
01 Sep 2002-Pain
TL;DR: A systematic review and subset meta‐analysis of published randomised controlled trials of psychological therapies for children and adolescents with chronic pain indicates that the psychological treatments examined are effective in reducing the pain of headache.
Abstract: A systematic review and subset meta-analysis of published randomised controlled trials of psychological therapies for children and adolescents with chronic pain is reported. A search of four computerised abstracting services recovered 123 papers from which 28 potential trials were identified. Eighteen met the criteria for inclusion in the review. The majority of these papers reported brief behavioural and cognitive behavioural interventions for children with headache and many were conducted in community (i.e. school) settings. Meta-analysis was applicable for 12 headache trials and one trial of recurrent abdominal pain using the Pain Index. The odds-ratio for a 50% reduction in pain was 9.62 and the number needed to treat was 2.32, indicating that the psychological treatments examined are effective in reducing the pain of headache. The quality of the 18 trials retrieved is narratively reviewed and suggestions for the development of trials in this field are made.

Journal ArticleDOI
01 Mar 2002-Pain
TL;DR: The data imply that VVS may reflect a specific pathological process in the vestibular region, superimposed on systemic hypersensitivity to tactile and pain stimuli.
Abstract: Vulvar vestibulitis syndrome (VVS) is a common cause of dyspareunia in pre-menopausal women. Little is known about sensory function in the vulvar vestibule, despite Kinsey's assertion that it is important for sexual sensation. We examined punctate tactile and pain thresholds to modified von Frey filaments in the genital region of women with VVS and age- and contraceptive-matched pain-free controls. Women with VVS had lower tactile and pain thresholds around the vulvar vestibule and on the labium minus than controls, and these results were reliable over time. Women with VVS also had lower tactile, punctate pain, and pressure-pain tolerance over the deltoid muscle on the upper arm, suggesting that generalized systemic hypersensitivity may contribute to VVS in some women. In testing tactile thresholds, 20% of trials were blank, and there was no group difference in the false positive rate, indicating that response bias cannot account for the lower thresholds. Women with VVS reported significantly more catastrophizing thoughts related to intercourse pain, but there was no difference between groups in catastrophizing for unrelated pains. Pain intensity ratings for stimuli above the pain threshold increased in a parallel fashion with log stimulus intensity in both groups, but the ratings of distress were substantially greater in the VVS group than in controls at equivalent levels of pain intensity. The data imply that VVS may reflect a specific pathological process in the vestibular region, superimposed on systemic hypersensitivity to tactile and pain stimuli.

Journal ArticleDOI
01 Sep 2002-Pain
TL;DR: It is suggested that several attentional processes can modify nociceptive processing in the brain at different stages, and LEP activities in the time‐range of N1 and N2 showed evidence of processes modulated by the direction of spatial attention.
Abstract: Laser evoked potentials (LEPs) are brain responses to activation of skin nociceptors by laser heat stimuli. LEPs consist of three components: N1, N2, and P2. Previous reports have suggested that in contrast to earlier activities (N1), LEPs responses after 230-250 ms (N2-P2) are modulated by attention to painful laser stimuli. However, the experimental paradigms used were not designed to specify the attentional processes involved in these LEP modulations. We investigated the effects of selective spatial attention and oddball tasks on LEPs. CO(2) laser stimuli of two different intensities were delivered on the dorsum of both hands of ten subjects. One intensity was frequently presented, and the other rarely. Subjects were asked to pay attention to stimuli delivered on one hand and to count rare stimuli, while ignoring stimuli on the other hand. Frequent and rare attended stimuli evoked enhanced N160 (N1) and N230 (N2) components in comparison to LEPs from unattended stimuli. Both components showed scalp distribution contralateral to the stimulus location. The vertex P400 (P2) was unaffected by spatial attention and stimulus location, but its amplitude increased after rare stimuli, whether attended or unattended. An additional parietal P600 component was induced by the attended rare stimuli. It is suggested that several attentional processes can modify nociceptive processing in the brain at different stages. LEP activities in the time-range of N1 and N2 (120-270 ms) showed evidence of processes modulated by the direction of spatial attention. Conversely, processes underlying P2 (400 ms) were not affected by spatial attention, but by the probability of the stimulus. This probability effect was not due to P3b-related processes that were observed at a later latency (600 ms). Indeed, P600 could be seen as a P3b evoked by conscious detection of rare targets.

Journal ArticleDOI
01 Sep 2002-Pain
TL;DR: Evidence is provided of the psychometric properties of a revised NCCPC (NCCPC‐R) with a larger cohort of children and Receiver operating characteristic curves suggest a score of 7 or greater on the NCCpc‐R as indicative of pain in children with cognitive impairments, with 84% sensitivity and up to 77% specificity.
Abstract: The non-communicating children's pain checklist (NCCPC) has displayed preliminary validity and reliability for measuring pain in children with severe cognitive impairments (Dev Med Child Neurol 42 (2000) 609). This study provides evidence of the psychometric properties of a revised NCCPC (NCCPC-R) with a larger cohort of children. Caregivers of 71 children with severe cognitive impairments (aged 3-18) conducted observations of their children using the NCCPC-R during a time of pain and a time without pain. Fifty-five caregivers completed a second set of observations. The score results on the NCCPC-R were: internally consistent, significantly related to pain intensity ratings provided by caregivers, consistent over time, sensitive to pain, and specific to pain. Analyses of children's individual scores indicated up to 95% of their scores were consistent. Receiver operating characteristic curves suggest a score of 7 or greater on the NCCPC-R as indicative of pain in children with cognitive impairments, with 84% sensitivity and up to 77% specificity. These results provide evidence of NCCPC-R having excellent psychometric properties.

Journal ArticleDOI
01 Nov 2002-Pain
TL;DR: Results indicate the effectiveness of tailor‐made CBT for patients at risk in relatively early RA, and supply preliminary support for the idea that customizing treatments to patient characteristics may be a way to optimize CBT effectiveness in RA patients.
Abstract: Recent developments in chronic pain research suggest that effectiveness of cognitive-behavioral therapy (CBT) may be optimized when applying early, customized treatments to patients at risk. For this purpose, a randomized, controlled trial with tailor-made treatment modules was conducted among patients with relatively early rheumatoid arthritis (RA disease duration of <8 years), who had been screened for psychosocial risk profiles. All participants received standard medical care from a rheumatologist and rheumatology nurse consultant. Patients in the CBT condition additionally received an individual CBT treatment with two out of four possible treatment modules. Choice of treatment modules was determined on the basis of patient priorities, which resulted in most frequent application of the fatigue module, followed by the negative mood, social relationships and pain and functional disability modules. Analyses of completers and of intention-to-treat revealed beneficial effects of CBT on physical, psychological and social functioning. Specifically, fatigue and depression were significantly reduced at post-treatment and at the 6-month follow-up in the CBT condition in comparison to the control condition, while perceived support increased at follow-up assessment. In addition, helplessness decreased at post-treatment and follow-up assessment, active coping with stress increased at post-treatment, and compliance with medication increased at follow-up assessment in the CBT condition in comparison to the control condition. Results indicate the effectiveness of tailor-made CBT for patients at risk in relatively early RA, and supply preliminary support for the idea that customizing treatments to patient characteristics may be a way to optimize CBT effectiveness in RA patients.

Journal ArticleDOI
01 Jul 2002-Pain
TL;DR: These calculations demonstrate that the interaction index can be measured by either an isobolar or an alternate method that is illustrated here, and do so with comparable precision.
Abstract: Two drugs used in combination may produce enhanced or reduced effects. The degree of enhancement or reduction is measured from the interaction index (gamma), a quantity that indicates the changed potency of the combination. The index is therefore a quantitative marker for the drug combination and effect metric used. Methodology for measuring the interaction index utilizes the combination and individual drug dose-effect data suitably modeled by regression techniques that most often produce linear plots of effect on log dose from which isobolar analysis is employed. The isobologram provides a simple and convenient graphical assessment of the interaction index but an independent statistical analysis is needed to assess its precision. In some cases, the relative potency of the constituent drugs is the same at all effect levels. When this is so, it is shown that the interaction index can be measured by either an isobolar or an alternate method that is illustrated here. These calculations demonstrate that these different methods of analysis yield the same value of gamma, and do so with comparable precision.

Journal ArticleDOI
01 Jan 2002-Pain
TL;DR: The findings suggest that treating and controlling pain may significantly enhance the subjective health and well‐being of community‐dwelling older adults.
Abstract: This study examined the impact of pain on self-rated health status in the community-dwelling older adults using the 1993 public release data of the Asset and Health Dynamics Among the Oldest Old (AHEAD). AHEAD is a population-based household survey designed to examine the dynamic interactions between health, family, and economic variables among US older adults. Results showed that 33% of the older adults reported frequent pain and 20% reported significant pain resulting in activity limitation. Controlling for clinical health status, socio-demographic characteristics, and access to medical care, logistic regression analyses showed that those who often have pain were more than twice as likely (odds ratio (OR)=2.63; confidence interval (CI)=2.35, 2.95; P=<0.0001) to perceive their health status to be "poor". Other predictors (P<0.01) include functional impairment (OR=2.78), chronic diseases (OR=1.89), minority status (OR=1.88), education (OR=1.77), and physician visits (OR=1.64). This study documents the adverse impact of pain on self-rated health as well as the fact that the experience of pain and poor subjective health and well-being is greatest among the most socially disadvantaged older adults (minorities and those with the least education). The findings suggest that treating and controlling pain may significantly enhance the subjective health and well-being of community-dwelling older adults.

Journal ArticleDOI
01 Jun 2002-Pain
TL;DR: Compared to females, males exhibited less negative pain responses when focusing on the sensory component of pain (i.e. increased threshold, tolerance and lower sensory pain), and emotional focusing was found to increase the affective pain experience of females.
Abstract: Research consistently indicates that gender differences exist in pain perception, with females typically reporting more negative responses to pain than males. It also seems as if males and females use and benefit from different coping strategies when under stress; females seem to prefer emotion-focused coping, whereas males prefer sensory-focused coping. Unfortunately, experimental research that examines such differences in the context of pain has not yet been adequately investigated. The aim of the current study was, therefore, to determine whether gender differences would be found in the effect that sensory-focused and emotion-focused coping instructions have on cold pressor pain experiences. Participants consisted of 24 male and 26 female healthy adults, all of whom reported no current pain. A consistent pattern of effects was found, over both behavioural and self-report measures of pain. Compared to females, males exhibited less negative pain responses when focusing on the sensory component of pain (i.e. increased threshold, tolerance and lower sensory pain). Furthermore, compared to sensory focusing, emotional focusing was found to increase the affective pain experience of females. Together these results confirm that important differences exist between men and women in the effects pain coping instructions have on the experience of pain. The implications of such findings for research and practice are discussed.