Pain
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We have reviewed our experience with spinal cord stimulation in treating patients with the failed back surgery syndrome and have assessed patient and patient-selection characteristics as predictors of the long-term outcome. Neuroradiological investigations eliminated the possibility of a surgically treatable lesion and electromyogram assessed the chronic radicular suffering in correlation with the complaints and the clinical examination of the patient. Excellent pain relief (75% or more) during 1 week of trial stimulation and no major psychiatric or psychological pathology were criteria of selection. ⋯ Thirty-five patients (55%) continued to experience at least 50% of pain relief at the latest follow-up. Fifty-eight patients (90%) were able to reduce their medication, 39 patients (61%) reported a change in lifestyle, in that their ability to perform daily activities had improved significantly. Fifty-three patients (83%) continued to use their device at the latest follow-up.
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In multiple studies cultural affiliation has been found to have an important influence on perception of and response to experimental and acute pain. Despite that evidence little work has been directed to understanding the cultural dimensions of the chronic pain experience. We present the results of a quantitative study of reported chronic pain perception in 372 chronic pain patients in six ethnic groups, who were under treatment at a multidisciplinary pain-management center. ⋯ This study suggests a biocultural model may be useful in conceptualizing the complex interaction of biological, cultural and psychosocial factors in the process of human pain perception. Although it is likely that intense pain affects attitudes and emotions, it is also very likely that attitudes and emotions influence reported perceptions of pain intensity. Pain intensity variation in this study population is not significantly associated with diagnosis, present medication types, or types of past treatments or surgeries for 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.