European journal of pain : EJP
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This study aims to assess whether the antinociceptive actions of methadone are mediated solely through opioid mechanisms, or whether its reported affinity for NMDA receptors has physiological relevance in vivo. Methadone is a mu-opioid receptor agonist reported to relieve pain unresponsive to other opioids. It is a racemic mixture comprising d- and l-optical isomers; the d-isomer has a lower affinity for opioid receptors, and both also exhibit NMDA receptor binding, likely to indicate antagonist activity. d -Methadone is antinociceptive in behavioural studies via non-opioid mechanisms, which could include functional NMDA receptor-blocking activity. ⋯ The inhibitory effects of both d - and dl -methadone on noxious-evoked activity were naloxone reversible. The naloxone reversibility of d -methadone inhibitions is best interpreted as indicative of a purely opioid mechanism of action. However, the ability of naloxone to reverse the effects of d -methadone may also reflect a degree of synergy between weak NMDA antagonist and opioid agonist activity.
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Clinical Trial
The symptom check-list, SCL-90-R: its use and characteristics in chronic pain patients.
The SCL-90-R is a widely-used questionnaire for self-report of psychological distress and multiple aspects of psychopathology, as part of the evaluation of chronic pain patients and other non-psychiatric populations. The aim of this study is the presentation of clinical results of this multidimensional questionnaire in a convenience sample of 3540 chronic pain patients treated in a multidisciplinary pain centre. ⋯ It is shown that the 9 dimensions postulated by Derogatis et al. (1977 a) cannot at all be distinguished in chronic pain patients. The use of single subscores of the SCL-90-R, often employed as a screening instrument for specific diagnoses, such as depression, is at least questionable in chronic pain patients.
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Clinical Trial
Relationship between mechanical sensitivity and postamputation pain: a prospective study.
Limb amputation is followed by stump and phantom pain in a large proportion of amputees and postamputation pain may be associated with signs of hyperexcitability such as hyperalgesia to mechanical stimulation. The present study examined the possible relationship between mechanical pain threshold of the limb and early (after 1 week) and late (after 6 months) phantom pain. Thirty-five patients scheduled for amputation of the lower limb were examined before, 1 week and 6 months after amputation. ⋯ One week after amputation there was a significant and inverse relationship between mechanical thresholds and phantom pain but no relationship was found after 6 months. The findings suggest that although tenderness of the limb before and after amputation is related to early stump and phantom pain, the relationship is weak. Neuronal sensitization peripherally or centrally may play a role in the development of phantom pain.
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In this study, 54 patients suffering from chronic cervicobrachialgia (mean pain duration 7 years) were treated with radiofrequency lesioning of the cervical spinal dorsal root ganglion (RF-DRG). The aim of the study was to investigate whether psychological variables would be predictive for the changes in pain intensity after medical treatment. ⋯ The level of catastrophizing before treatment appeared to predict 10% of the changes in pain intensity after treatment. Changes in pain intensity after RF-DRG were positively correlated with changes in psychosocial dysfunction and negative self-efficacy.
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To what degree can facial expression scales help children differentiate between the sensory and emotional aspects of the pain experience? This study examined the relationship between children's ratings on the Faces Pain Scale (an intensity measure), the Facial Affective Scale (an affective measure), and a paired mechanical visual analogue (MVAS) method for measuring the intensity and unpleasantness of pain. It was predicted that ratings on the Faces Pain Scale should correlate best with the MVAS measure of pain intensity rather than unpleasantness. Likewise, ratings on the Facial Affective Scale should correlate best with the MVAS measure of pain unpleasantness (assumed to reflect an emotional dimension) rather than intensity. ⋯ No systematic age effects were observed. In conclusion, the Faces Pain Scale and the Facial Affective Scale may partly measure different aspects of the pain experience in children, although it remains to be determined to what degree the obtained differences are clinically meaningful. Copyright 1999 European Federation of Chapters of the International Association for the Study of Pain.