Pain
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A method to measure cutaneous hyperalgesia to thermal stimulation in unrestrained animals is described. The testing paradigm uses an automated detection of the behavioral end-point; repeated testing does not contribute to the development of the observed hyperalgesia. ⋯ Both the thermal method and the Randall-Selitto mechanical method detected dose-related hyperalgesia and its blockade by either morphine or indomethacin. However, the thermal method showed greater bioassay sensitivity and allowed for the measurement of other behavioral parameters in addition to the nociceptive threshold.
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Pain to light touching of the skin is a hallmark sign of causalgia. The purpose of this study was to determine whether myelinated or unmyelinated afferent fibers signal this hyperalgesia. Sensory testing was performed in 17 patients with long-standing hyperalgesia after nerve injury. ⋯ The mean latency for detection of pain in the hyperalgesic region was 414 +/- 18 msec, compared to 458 +/- 16 msec for the detection of touch to the same stimuli applied to the opposite normal foot. These 3 lines of evidence indicate that myelinated primary afferents, perhaps A beta fibers, signal the hyperalgesic pain in causalgia. These fibers may be sensitized A beta nociceptors or low-threshold mechanoreceptors.
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The reflex sympathetic dystrophy syndrome (RSDS) consists of a triad of pain, edema and sympathetic dysfunction of an extremity following trauma, peripheral nerve injury or central nervous system disorder. Reflex sympathetic dystrophy syndrome is a difficult and costly pain syndrome to treat. One of the difficulties in evaluating treatment efficacy is the objectification and quantification of patient findings. ⋯ Skin temperature was not predictive of changes in joint pain score, AROM, limb volume or subjective pain measures. However, there was internal consistency between volumetric and AROM measures and joint pain indices. This protocol is recommended for use in therapeutic trials for the treatment of the RSDS.
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Recordings were made from dorsal horn neurones in the spinal cord and trigeminal nucleus caudalis of intact anaesthetized rats. These rats had been rendered polyarthritic by s.c. injection of Mycobacterium butyricum suspended in oil into the base of the tail. The experiments were carried out during the acute phase of the illness (3-4 weeks post inoculation) during which hyperalgesia occurred. ⋯ The activity of non-noxious neurones was never modified by any heterotopically applied stimuli. By contrast, all convergent neurones were inhibited by heterotopic stimuli, noxious (52 degrees C, pinch) or non-noxious (light and mild pressure), applied to inflamed areas. While the inhibition triggered by noxious stimuli was reminiscent of that observed in healthy rats, the inhibition triggered by non-noxious mechanical stimuli was related to the inflammatory state of the part of the body stimulated, the most sensitive areas being the hind paws.(ABSTRACT TRUNCATED AT 400 WORDS)
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Epidural administration of opiates as a long-term treatment of cancer pain, even for out-patients, is now well established. Most reports describe intermittent injections given several times a day, which may have technical and personal disadvantages. ⋯ This report describes 16 patients who were treated with epidural opiates delivered by plastic infusion pumps. Pain relief was effective, the equipment was inexpensive and home treatment was easily accomplished.