Pain
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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.
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Dorsal horn neurons that respond to noxious cold also respond to noxious heat, suggesting the hypothesis that pain evoked by temperature extremes, whether hot or cold, may be processed similarly in the CNS. In this study, we tested perceptual consequences of this hypothesis by comparing characteristics of heat and cold pain, as well as of innocuous warm and cool. Eight healthy subjects performed psychophysical tasks involving hot and cold cutaneous stimuli. ⋯ Perceived stimulus intensity was compared to temperature recordings from intradermal and skin surface thermocouples. Heat pain, cool and warmth appeared to depend on surface temperature, whereas cold pain was related to subcutaneous temperature, suggesting different receptors for noxious heat and noxious cold. These data, combined with results of human brain imaging and primate electrophysiological studies, suggest that the unpleasantness associated with both heat pain and cold pain is processed similarly in the CNS, whereas differential information about stimulus quality is preserved in the cerebral cortex.
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Randomized Controlled Trial Clinical Trial
Infiltration of morphine into an abnormal wound; effects on pain relief and endocrine/immune response.
We wanted to evaluate pain relief and endocrine/immune response after local administration of morphine into an abdominal wound. In a randomised double blind design 29 patients undergoing hysterectomy received two blinded injections of morphine and saline. Before surgery the patients in the control group (n = 15) got 10 mg of subcutaneous morphine into an arm and at skin incision 30 ml of saline was infiltrated directly into the wound. ⋯ High doses of i.v. morphine reduced cortisol and IL-6 levels in the early hours after surgery. The injection of morphine into the wound did not improve pain relief or reduce the consumption of i.v. morphine after surgery. The endocrine stress response to trauma was modified by preoperative administration of morphine.
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Comparative Study Clinical Trial Controlled Clinical Trial
Pain processing during three levels of noxious stimulation produces differential patterns of central activity.
Previous functional imaging studies have demonstrated a number of discrete brain structures that increase activity with noxious stimulation. Of the commonly identified central structures, only the anterior cingulate cortex shows a consistent response during the experience of pain. The insula and thalamus demonstrate reasonable consistency while all other regions, including the lentiform nucleus, somatosensory cortex and prefrontal cortex, are active in no more than half the current studies. ⋯ Decreased rCBF was observed in the amygdala region. These responses were interpreted with respect to their contribution to the multidimensional aspects of pain including fear avoidance, affect, sensation and motivation or motor initiation. It is suggested that future studies examine the precise roles of each particular region during the central processing of pain.