Pain
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The Faces Pain Scale (FPS; Bieri et al., Pain 41 (1990) 139) is a self-report measure used to assess the intensity of children's pain. Three studies were carried out to revise the original scale and validate the adapted version. In the first phase, the FPS was revised from its original seven faces to six, while maintaining its desirable psychometric properties, in order to make it compatible in scoring with other self-rating and observational scales which use a common metric (0-5 or 0-10). ⋯ There were no significant differences between the means on the FPS-R and either of the analogue scales. The FPS-R is shown to be appropriate for use in assessment of the intensity of children's acute pain from age 4 or 5 onward. It has the advantage of being suitable for use with the most widely used metric for scoring (0-10), and conforms closely to a linear interval scale.
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Clinical Trial Controlled Clinical Trial
Osteoarthritis and its association with muscle hyperalgesia: an experimental controlled study.
Hypertonic saline effectively excites muscle nociceptors. Muscle hyperalgesia was assessed in osteoarthritis (OA) by intramuscular infusion of 0.5 ml hypertonic saline (6%) into the tibialis anterior muscle in humans. Patients (n=14) with OA in the lower extremities were compared with an equal number of age- and sex-matched healthy controls. ⋯ OA patients had increased pain intensity VAS after the infusion in the right leg compared with controls (P<0.05). Referred and radiating pain areas at 2 min post-infusion increased in OA patients and not in controls as compared with the local pain areas (P<0.05). It is concluded that muscle hyperalgesia and extended pain areas might be due to central sensitization caused by painful osteoarthritis.
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Clinical Trial
Methadone maintenance patients are cross-tolerant to the antinociceptive effects of morphine.
We have previously shown that methadone maintenance patients are hyperalgesic. Very little is known about the antinociceptive effects of additional opioids in these patients. This study (1) compared the intensity and duration of antinociceptive responses, at two pseudo-steady-state plasma morphine concentrations (C(SS1) and C(SS2)), between four patients on stable, once daily, doses of methadone and four matched control subjects; and (2) determined, in methadone patients, whether the antinociceptive effects of morphine are affected by changes in plasma R(-)-methadone concentration that occur during an inter-dosing interval. ⋯ The fluctuations that occurred in plasma R(-)-methadone concentration during an inter-dosing interval had little effect on patients' responses to morphine. Our findings suggest that methadone patients are cross-tolerant to the antinociceptive effects of morphine, and conventional doses of morphine are likely to be ineffective in managing episodes of acute pain amongst this patient group. Further research is needed to determine whether other drugs are more effective than morphine in managing acute pain in this patient population.
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In order to analyze the pathophysiology behind the clinical similarity acutely after limb trauma and in acute stages of complex regional pain syndrome (CRPS), 20 patients with external fixation after distal radius fracture (3.5 days after surgery) without signs of CRPS and 24 patients suffering from acute CRPS I (without nerve lesion; duration, 5 weeks) were investigated. Hyperalgesia to heat was tested by a feedback-controlled thermode, and to mechanical stimuli by an impact stimulator. The sympathetic nervous system was examined by measuring skin temperature (infra-red thermography), testing different sympathetic vasoconstrictor reflexes (laser-Doppler flowmetry) and quantitative sudometry after thermal load (thermoregulatory sweat test). ⋯ Our results indicate that pain and vasomotor disturbances may be generated by different mechanisms acutely after trauma and in acute CRPS. Despite the clinical similarity, additional changes in the peripheral or central nervous system are required for CRPS. In the light of our observations, it seems unlikely that CRPS is a simple exaggeration of post-traumatic inflammation.
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Comparative Study
Effect of gabapentin and lamotrigine on mechanical allodynia-like behaviour in a rat model of trigeminal neuropathic pain.
Injury to the trigeminal nervous system may induce severe pain states. This study examined the antinociceptive effect of the novel anticonvulsants, gabapentin and lamotrigine, in a rat model of trigeminal neuropathic pain produced by chronic constriction of one infraorbital nerve. Responsiveness to von Frey filament stimulation of the vibrissal pad was evaluated 2 weeks post-operation. ⋯ Repeated (30 and 50 mg/kg), but not single (30-100 mg/kg) injections of i.p. gabapentin partially alleviated the mechanical allodynia-like behaviour. Repeated injections of gabapentin at 50 but not at 30 mg/kg produced motor deficits. The results indicate that gabapentin rather than lamotrigine may be a better therapeutic approach for the clinical management of some trigeminal neuropathic pain disorders.