Pain
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Clinical Trial
Catastrophizing, depression and the sensory, affective and evaluative aspects of chronic pain.
Research has shown that catastrophizing is related to increased depression and chronic pain. However, some researchers have questioned the utility of catastrophizing as a separate construct, suggesting that it may just be a symptom of depression. The present investigation used path analysis to determine if catastrophizing was related to McGill Pain Questionnaire scores when controlling for depression as assessed by the Beck Depression Inventory in a group of 85 chronic pain patients. ⋯ The resulting path coefficients appear to support these predictions. The results suggest that catastrophizing is a separate construct which may impact on pain perception and treatment. The data also provide some support for Field's neurobiological model of the relationship between depression and pain.
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The experimental arthritis of the knee joint used in the present study leads to joint swelling, increased joint temperature, limping, guarding, and a decrease in paw withdrawal latency (PWL) to radiant heat (hyperalgesia) within hours in rats. Unexpectedly, administration of the non-NMDA receptor antagonist, CNQX, in the spinal cord 4 h after initiation of the arthritis significantly reduced the degree of joint inflammation and returned PWL times to baseline. Therefore, the present results indicate that established joint swelling and hyperalgesia can be reduced significantly by CNQX.
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The rat foot withdrawal response to noxious radiant heat has been used as a model of nociception that is particularly useful for measurements of unilateral changes in nociceptive responses. The purpose of these studies was to characterize the foot withdrawal response to graded rates of noxious skin heating. Response latencies and both surface and subsurface temperatures produced by 6 different intensities of radiant heat were measured to determine whether response latency is an appropriate measure of nociceptive threshold. ⋯ These results and published reports of nociceptive afferent recordings which used similar skin heating parameters, indicate that nociceptive foot withdrawal responses occur at about the same skin temperature as the activation of nociceptors. These results also indicate that since constant intensity heating produces linear increases in the subsurface temperature, then response latency can be used as an accurate measure of changes in nociceptive threshold produced by drug treatments. These observations lead to the conclusion that the foot withdrawal response latency is a valid and useful measure of nociceptive threshold in rodents.
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Randomized Controlled Trial Comparative Study Clinical Trial
Relief of post-herpetic neuralgia with the N-methyl-D-aspartic acid receptor antagonist ketamine: a double-blind, cross-over comparison with morphine and placebo.
Pain and sensory thresholds were examined before and after intravenous administration of ketamine (0.15 mg/kg), morphine (0.075 mg/kg) or saline in 8 patients with post-herpetic neuralgia. A randomized, double-blind, cross-over study design was used. Post-herpetic neuralgia was associated with impaired sensory function, as shown by reduced tactile and warm sensation in the affected compared with the contralateral non-affected skin area. ⋯ Side effects were observed in all the 8 patients after injection of ketamine and in 6 patients after injection of morphine. The present results support the hypothesis that the N-methyl-D-aspartic acid (NMDA) receptors are involved in the control of post-herpetic neuralgia including allodynia and wind-up-like pain. The NMDA receptors also may play a role in the modulation of thermal perception.