Pain
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This study was designed to examine the central changes in the receptive field properties of dorsal horn neurones induced by a period of visceral noxious stimulation. The aim of this investigation was to establish whether noxious stimulation of the visceral input to the spinal cord could influence transmission of cutaneous information through dorsal horn neurones. Single-unit electrical activity was recorded in the lower thoracic spinal cord of anaesthetized cats from dorsal horn neurones with a somatic receptive field in the ipsilateral flank. ⋯ The increases were large and lasted for at least 20 min. None of the 9 spinal cord neurones without an input from the gall bladder were affected by the conditioning visceral stimulus even though 7 showed changes in receptive field size when the animals were spinalised. These results show that noxious stimulation of viscera can evoke increases in the somatic receptive fields of spinal cord neurones but only of those neurones which are also driven by the visceral stimulus.
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This paper reports the development and validation of the Pain Beliefs Questionnaire (PBQ). This is a 20-item questionnaire covering beliefs about the cause and treatment of pain. It was administered to 294 subjects, comprising 100 chronic pain patients and 194 controls. ⋯ Secondly, as predicted significant associations were observed between scores on the Organic Beliefs scale and scores on the Chance and Powerful Others scales of the Multidimensional Health Locus of Control (MHLC), and also between the Psychological Beliefs and Internal scales of the MHLC. No relationship, however, emerged between these scales and measures of pain intensity. The implications of these findings for the assessment and management of chronic pain patients, and in the understanding of the development of chronic pain, are discussed.
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Electrical stimulation of the subdiaphragmatic branch of the vagus nerve (SDVAS) inhibits the nociceptive tail flick (TF) reflex. The present experiments examined (1) the central substrates mediating SDVAS-produced inhibition of the TF reflex and (2) the effects of SDVAS on either background or noxious heat-evoked responses of spinal dorsal horn neurons. Microinjections of ibotenic acid in the ipsilateral nucleus tractus solitarius (NTS), nucleus raphe magnus (NRM), or bilateral locus coeruleus/subcoeruleus (LC/SC) significantly increased the intensity of SDVAS required to inhibit the TF reflex in lightly anesthetized rats. ⋯ SDVAS produced a significant rightward, parallel shift in the stimulus response function (SRF) of class-2 neurons to noxious, graded heat stimuli ranging from 40 to 52 degrees C, while SDVAS produced a significant increase in the threshold and a significant reduction in the slope of the SRF of class-3 neurons. These data indicate that SDVAS generally inhibits noxious heat-evoked responses of lumbosacral spinal dorsal horn neurons in the rat, but does not significantly affect background activity of the same neurons. Furthermore, the inhibition of the TF reflex produced by SDVAS depends on central relays in the ipsilateral NTS, NRM, and bilateral LC/SC.
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Randomized Controlled Trial Clinical Trial
The postmastectomy pain syndrome and topical capsaicin: a randomized trial.
This paper describes a randomized parallel trial of topical 0.075% capsaicin versus vehicle (placebo) in the postmastectomy pain syndrome (PMPS). The study was double-blind in design; however, this was compromised by the burning sensation induced by capsaicin. ⋯ Five of 13 patients on capsaicin were categorized as good-to-excellent responses with 8 (62%) having 50% or greater improvement. Only 1 of 10 cases had a good response to vehicle with 3 rated as 50% or better.
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Differences in the use of coping strategies have been hypothesized to explain some of the variation in adaptation among chronic pain patients. Investigators often assess coping using composite indices of different coping strategies. Although the use of composite measures has advantages, it may obscure the importance of specific coping strategies as they relate to functioning. ⋯ The scales and ratings of the CSQ were factor analyzed to create composite measures, and the ability of the composite scores and individual scales to predict adjustment was compared. The results indicated that the individual scales provided more information than the composite measures regarding the relationship between coping and adjustment to chronic pain. The results also suggested that individual scale scores may be more useful than composite scores in identifying the conditions under which coping efforts have their greatest effects on adjustment.