Pain
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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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Chronic low back pain (CLBP) patients with pain and symptomatology incongruent with physical pathology have been found to have a poorer outcome to medical treatment and rehabilitation, and to use health care resources excessively. To examine possible psychological and behavioral bases for this pattern, this investigation contrasted 40 CLBP patients who displayed non-organic physical signs, inappropriate symptoms, and/or anatomically incongruent pain drawings with 40 'control' CLBP patients without incongruent pain criteria. Multivariate analyses revealed that the incongruent CLBP group reported greater pain intensity and depression, received higher observer ratings of pain, displayed more ambulatory/postural pain behavior, and reported more dysfunctional cognitions during pain. ⋯ Incongruent CLBP patients still displayed more maladaptive and dysfunctional cognitions. These findings indicate that incongruent CLBP patients may be conceptualized as ineffective and overwhelmed in their attempts to cope and as more physically disabled as a result of their pain. The role of cognitive factors, reasons for failure of physically based interventions, and implications for patient management are discussed.
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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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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.