Pain
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Evidence indicates that excitatory amino acids (EAAs) like glutamate and aspartate are important in the processing of nociceptive information in the dorsal horn of the spinal cord. Recently, the role of particular EAA receptors in pain transmission and facilitated pain states has been examined utilizing spinal administration of specific receptor antagonists. Most investigators have studied the involvement of N-methyl-D-aspartate (NMDA) EAA receptors in hyperalgesia and nociception; less is known about the importance of non-NMDA EAA receptors in animal models of persistent pain. ⋯ Intrathecal NBQX also inhibited non-evoked pain behavior. In conclusion, non-NMDA receptor antagonists produced a marked decrease in pain behaviors in this model of postoperative pain. Thus, non-NMDA receptors are important for the maintenance of short-term pain behaviors caused by an incision and drugs blocking these receptors may be useful for the treatment of postoperative pain in patients.
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Psychophysical methods were used to investigate pain in human subjects elicited by controlled freezing of the skin using a novel vortex thermode. When cooling stimuli delivered with a small thermode (7 mm diameter) exceeded the normal cold pain threshold into the sub-zero temperature range (-5 to -11 degrees C), all subjects reported an intense, sharp stinging pain sensation which occurred suddenly and was readily differentiated from normal cold pain. The onset of this stinging 'freezing' pain was closely correlated with a sudden increase in skin temperature beneath the thermode of 4.77+/-0.86 degrees C (+/-SD) associated with the phase transition of supercooled water to ice. ⋯ The changes in thermal sensitivity were not accompanied by consistent changes in mechanical sensitivity. These results indicate that a characteristic sharp, stinging pain is reliably evoked abruptly at the phase transition of supercooled skin water to ice The ensuing brief decrease in cold pain threshold with burning quality, coupled with decreased sensitivity to cold, are speculated to reflect a central disinhibition of C-fiber nociceptor input due to reduced cold fiber activity. These effects may be relevant to frostbite, and distinguish themselves from the more pronounced thermal and mechanical hyperalgesia seen following intense freeze lesion of the skin.
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Gabapentin is an effective option for the treatment of neuropathic pain syndromes because of its efficacy and favorable side-effect profile. A case is presented of a 58 year old man who developed a painful polyneuropathy while being treated with gabapentin.
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Clinical Trial Controlled Clinical Trial
Learning to live with the pain: acceptance of pain predicts adjustment in persons with chronic pain.
When patients find their pain unacceptable they are likely to attempt to avoid it at all costs and seek readily available interventions to reduce or eliminate it. These efforts may not be in their best interest if the consequences include no reductions in pain and many missed opportunities for more satisfying and productive functioning. The purpose of this study was to examine acceptance of pain. ⋯ Regression analyses showed that acceptance of pain predicted better adjustment on all other measures of patient function, independent of perceived pain intensity. These results are preliminary. Further study will be needed to show for whom and under what circumstances, accepting some aspects of the pain experience may be beneficial.
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Myoclonus occasionally occurs in the perioperative setting and in patients on chronic opioid therapy. It appears to be dose-related in a unpredictable manner. Different mechanisms have been proposed to explain the occurrence of a series of neuromuscular disturbances probably sharing final common pathways. ⋯ Adjuvant drugs, such as benzodiazepines or dantrolene may avoid the reduction of the opioid dose while maintaining an acceptable analgesia. Current practice suggests a change in opioid when pain control is not obtained at opioid doses resulting in unacceptable adverse effects, including myoclonus and hyperalgesia. A change in the type of opioid may be useful in patients who develop severe central adverse effects, even if these patients appear to have normal renal function or hydration status.