Pain
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The present study investigated the effect of the child's pain catastrophizing and self-reported pain upon the child's facial expression of pain and parental inferences of their child's pain. School children (n=62) experienced pain by taking part in a cold water procedure. Analyses revealed that more intense pain was associated with higher levels of facial pain expression in children who reported a low frequency of catastrophizing. ⋯ A similar pattern was obtained for the pain inferences by the parent: pain intensity as reported by the child was positively related to pain inferences by the parent in children who reported a low frequency of catastrophizing, but such relationship was not significant for children with high catastrophizers. Further analyses revealed that when pain intensity was low, parents of high catastrophizing children judged the pain of their child to be higher than parents of low catastrophizing children. The implications of the findings are discussed in terms of the importance of assessing different dimensions of pain encoded in expression, different types of pain expression, and its differential effects upon others.
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Many studies have investigated the highly relevant association between pain and disability in clinical groups using the Pain Disability Index (PDI). To interpret these results, knowledge of disability in the general population is crucial. Moreover, to investigate criterion validity of the PDI, the influence on health care utilisation (HCU) is of special interest. ⋯ The PDI is an economical, reliable and valid self-rating instrument for assessing disability caused by physical symptoms. HCU in the general population is determined by the number and severity of somatic complaints and also by disability. Symptoms and disability play a crucial but somewhat independent role.
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Randomized Controlled Trial
The effect of attentional re-training and threat expectancy in response to acute pain.
This study aimed to investigate the efficacy of implicit attention re-training (AR) on pain ratings, threshold and tolerance during the cold-pressor task and to determine whether the effectiveness of AR was affected by threat expectancy. One hundred and four undergraduate psychology students were randomly assigned to receive either threat-alleviating or threat-inducing information about the task. Participants were then re-randomized to receive an AR that either trained them to implicitly attend to neutral and ignore pain-related stimuli (neutral training) or to attend towards pain-related stimuli (pain training). ⋯ For initial pain ratings, there was an interaction that closely approached significance (p=0.053). These results show that AR affects individual's perceptions of and their responses to pain during an experimental task in a similar way to increasing the threat expectancy of the task. Future research should trial AR in real-life settings to determine whether these results can be generalized.
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Repetitive transcranial magnetic stimulation (rTMS) has had partly incongruous effects on cutaneous sensibility, and there are no systematic studies on the effects of rTMS on facial sensory function. We assessed modulation of thermal sensitivity of facial skin in healthy subjects by navigated rTMS (10 Hz), enabling accurate localization of predefined cortical targets: right primary motor cortex (M1) of facial muscles, primary somatosensory cortex (S1) representing the cheek, dorsolateral prefrontal cortex (DLPFC), and secondary somatosensory cortex (S2); the control site was occipital cortex (OCC). Applying signal detection theory, we investigated whether the rTMS-induced changes in heat-pain threshold (HPT) relate to an alteration in the subject's discriminative capacity (sensory factor) or response criterion (non-sensory factor). ⋯ Stimulation of M1 decreased capacity to discriminate painful heat without influencing HPT; there was large interindividual variation in rTMS effects in the M1/S1 areas. Detection threshold for innocuous warming rose similarly after rTMS of M1, S1, DLPFC, S2 and OCC, whereas sensibility to innocuous cooling transiently improved after rTMS of S1. The results indicate that rTMS applied anatomically accurately to S2 may produce analgesia in the face via multiple mechanisms, partly depending on gender, and involving decreased discriminative capacity and increased response criterion.
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Relatively little is known on pain-induced neurotransmitter release in the human cerebral cortex. We used proton magnetic resonance spectroscopy (1H-MRS) during tonic painful heat stimulation to test the hypothesis of increases in both glutamate and GABA, two neurotransmitters with a key role in pain processing. Using a 3T MR scanner, we acquired spectra from the rostral anterior cingulate cortex (rACC) in 13 healthy right-handed subjects at rest and during painful heat stimulation. ⋯ No changes in glutamate concentrations were detected during noxious stimulation. This study provides the first evidence that GABA is released in the human cerebral cortex during painful stimulation. The results are in line with animal findings on the role of GABA in pain processing and with studies in humans showing analgesic efficacy of GABA-related drugs in clinical pain conditions.