Pain
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Touch evoked agitation (allodynia) can be induced by spinal delivery of strychnine and this effect is antagonized by intrathecal NMDA and non-NMDA receptor antagonists, but not by mu-opiate receptor agonists. In this study, we sought to characterize the effect of focal glycine-receptor inhibition on spontaneous and evoked activity in dorsal horn neurons of the chloralose-anesthetized cat. Strychnine (1 mM) applied near the neurons through a dialysis fiber caused an enhanced response to hair deflection, enlargement of the low threshold receptive fields and in some cells, an increase in afterdischarge. ⋯ Consistent with these data is the contention that under normal circumstances, afferent hair follicle input onto convergent neurons is regulated by a tonic glycinergic circuit. Removal of this regulatory influence leads to a magnification of low threshold tactile throughput in dorsal horn. This model may help to provide pharmacological insights into more efficacious treatments for such pain states that are relatively refractory to opioid therapies.
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Clinical Trial Controlled Clinical Trial
Development and preliminary validation of a postoperative pain measure for parents.
Parents are now primarily responsible for the at home assessment and treatment of their children's pain following minor surgery. Although some research has suggested that parents underestimate their children's pain following surgery, no behavioral measure exists to assist parents in pain assessment. The Postoperative Pain Measure for Parents was developed based on cues parents reported using to assess their children's pain (e.g. changes in appetite, activity level). ⋯ This study provides preliminary evidence for the use of the Postoperative Pain Measure for Parents as a valid assessment tool with children between the ages of 7-12 years following day surgery. It is internally consistent and strongly related to child-rated pain. Future research should explore the use of this measure with a younger sample and children with developmental delays.
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Clinical Trial Controlled Clinical Trial
Effect of present pain and mood on the memory of past postoperative pain in women treated surgically for breast cancer.
In our recent retrospective study on breast cancer patients, the intensity of the past postoperative pain was a primary factor in predisposing the development of chronic post-treatment pain. The present prospective study was designed to find out if the remembered intensity of postoperative pain (RIPP) after breast surgery was influenced by the development of chronic pain and if the RIPP had any correlation with the development of depression or anxiety. The patient's estimation of the severity of the RIPP was determined three times in the year after surgery. ⋯ Their depression remained at a higher level during the first year after surgery. The results suggest that the amount of postoperative pain may play a role in the development of chronic pain. However, the development of chronic pain is connected to a tendency to overestimate previous pain and to higher levels of depression.
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Compounds related to capsaicin and its ultrapotent analog, resiniferatoxin (RTX), collectively referred to as vanilloids, interact at a specific membrane recognition site (vanilloid receptor), expressed almost exclusively by primary sensory neurons involved in nociception and neurogenic inflammation. Desensitization to vanilloids is a promising therapeutic approach to mitigate neuropathic pain and pathological conditions (e.g. vasomotor rhinitis) in which neuropeptides released from primary sensory neurons play a major role. Capsaicin-containing preparations are already commercially available for these purposes. ⋯ We further focus on ligand-induced messenger plasticity, a recently discovered mechanism underlying the analgesic actions of vanilloids. Lastly, we give a brief overview of the current clinical uses of vanilloids and their future therapeutic potential. The possibility is raised that vanilloid receptor subtype-specific drugs may be synthesized, devoid of the undesirable side-effects of capsaicin.