Pain
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Based upon a tripartite theoretical model of pain, the Pain Rating Index (PRI) of the McGill Pain Questionnaire (MPQ) continues to be one of the most frequently used instruments to measure clinical pain. Although a number of exploratory factor analytic studies have failed to consistently support the theoretical structure of the instrument, one previous confirmatory factor analytic study of chronic pain did statistically support the a priori model. Because it has been suggested that acute pain may not involve the same dimensions as chronic pain, this study provided a direct test of the theoretical structure of the MPQ through multi-sample confirmatory factor analysis (CFA) using data provided by women experiencing pain during labor (n = 185) and women experiencing acute postoperative pain (n = 192). Results of the LISREL CFA analysis indicated that the a priori, 3-factor, oblique model originally proposed by Melzack provided the most parsimonious representation of the data across the 2 samples of acute pain.
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Fibromyalgia syndrome (FS) is a chronic pain disorder characterized by diffuse musculoskeletal soreness, stiffness, non-restorative sleep and psychological disturbance. At present, much about the etiology, pathological mechanisms and course of FS are unknown. Indeed, standardized diagnostic criteria have only been recently agreed upon. ⋯ The present paper describes the clinical presentation of FS and historical conceptualizations of the disorder. Available research on pathophysiological mechanisms in FS is then presented. In this section we have included literature concerning histology of muscle, sleep architecture, neurotransmitter anomalies and neuropeptide involvement in FS symptomatology.
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This study examined the extent to which measures of anxiety could predict pain and the length of hospitalization following surgery in 111 patients with gallstones over and above what could be predicted on the basis of biographical and medical status variables. Self-reported pain on the third day postoperative could hardly be explained by the variables measured. ⋯ Over and above these variables. A-state on the third postoperative day and also A-state and specific anxiety measured 1 day before surgery exerted a significant increase on the values of prediction of the length of postoperative hospitalization.
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Comparative Study
Comparison of human pain sensation and flexion withdrawal evoked by noxious radiant heat.
The purpose of this study was to determine the reliability of flexion withdrawal magnitude as an indicator of pain sensation. In 10 healthy human volunteers, we compared the magnitude and latency of integrated biceps EMG with the subjects' rating of pain, using a visual analog scale, elicited by noxious radiant heat stimuli applied to the dorsal forearm. ⋯ The pain intensity and withdrawal magnitude for each stimulus were poorly correlated. Under the conditions of this experiment, mean pain intensity and mean withdrawal magnitude were both well correlated with stimulus temperature, but the magnitude of withdrawal did not reliably reflect the intensity of pain sensation.
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The objective of this work was to simultaneously measure pain-related spinal and supraspinal physiological responses in humans. The sural nerve compound action potential (CAP), the spinal withdrawal reflex (RIII), the somatosensory evoked potential (SEP) and subjective magnitude ratings were elicited by electrical stimulation of the sural nerve in 10 healthy subjects. The sural nerve CAP was used to normalize the evoking stimulus current and to help identify the peripheral nerve afferent types contributing to the physiological and psychophysical responses. ⋯ Although the amplitudes of the P200 and P300 peaks of the SEP were significantly related to stimulation at noxious levels, both were also affected by stimulation at innocuous levels. This result implies that these peaks receive contributions from both noxious and innocuous somatosensory processes. Clearly, the non-pain-related components of these SEP peaks must be identified and isolated before their potential in measuring supraspinal nociceptive processes can be fully realized.