Pain
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Long-term outcomes for 300 chronic back pain patients were assessed retrospectively by a telephone follow-up 4-6 years after the patients were evaluated by a multi-disciplinary rehabilitative program. A Perception of Disability scale, developed to rate subjective disability, was used along with objective measures of functioning. On objective measures, 56% of patients reported themselves working or work ready, 58% no longer received compensation, 62% were taking no prescription medications and 65% had no or brief medical treatment since evaluations. ⋯ There was a strong relationship between perceived disability and objective circumstances with 63% of the patients unable to work and 61% still on disability payments reporting their disability as increasing. Of the 48 patients reporting back surgery at some point after evaluation only 17% perceived themselves as improved while 58% considered themselves worse. These results are discussed in the context of the development of pain focussed lifestyles.
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Comparative Study
The dimensions of pain: a multidimensional scaling comparison of cancer patients and healthy volunteers.
This paper presents a new approach to the measurement and understanding of clinical pain. A multidimensional scaling (MDS) procedure was used to analyze pairwise similarity judgments made to 9 pain descriptors by 24 cancer pain patients and 24 healthy volunteers. The question was whether the dimensions of the global pain space differed between the 2 groups. ⋯ The subject weight space revealed that the Pain Intensity dimension was the most important dimension for the patients, while Emotional Quality was more salient for the volunteers. Wide differences were found in the salience of the various dimensions to different individuals; this information may prove useful for tailoring patient treatment. The study demonstrates that MDS procedures such as INDSCAL, in which the subjects (rather than the researcher) determine the number and characteristics of the global pain dimensions, will improve our understanding and treatment of pain.
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Case Reports
An unusual case of causalgia. Relevance to recent hypothesis on mechanism of causalgia.
Intravenous regional sympathetic block with guanethidine caused only limited improvement in a patient with longstanding causalgia. Lumbar sympathetic block with phenol also had little direct effect on the pain but completely abolished associated allodynia and vasomotor signs. ⋯ This improvement persisted even after 8 months when there was some return of the previous allodynia and vasomotor signs (to involve a smaller area than previously). The case would appear to have implications for a recently proposed hypothesis concerning the mechanism of pain in causalgia.
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In the first part of the study 20 subjects (11 headache, 9 normals) free-sorted descriptors from the intensity and affect scales of the Tursky pain perception profile (PPP) into groups on the basis of similar meaning. In part 2 they made similarity ratings of all pairs of words within the intensity and affect scales. In the third part of the study subjects completed a cross-modal matching task to scale the intensity and affect words. ⋯ An MDS analysis showed that the groups could be located in 2-dimensional space in which the dimensions of intensity and affective distress could be easily discerned. When the descriptors from the intensity and affect scales were rated within each scale, a second MDS analysis showed that, whereas the intensity descriptors could be fitted by a 1-dimensional representation, the affect descriptors required a 3-dimensional model. There was evidence that subjects with extensive pain experience placed greater weight on the second and third affective dimensions compared with relatively pain-free subjects.
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Intrathecal administration of glycine (strychnine) or GABA (bicuculline) but not opioid (naloxone), adrenergic (phentolamine) or serotonin (methysergide) receptor antagonists resulted in a dose-dependent organized agitation response to light tactile stimulation. This effect was maximally evoked by oscillating but not continuous stimulation applied to a dermatome corresponding to the levels of spinal cord acted upon by the intrathecal antagonist. Similar results were observed in chloralose-urethane anesthetized rats in which tactile stimulation evoked hypertensive responses following local tactile stimuli. ⋯ At doses below those which produced motor dysfunction, however, these agents had no effects on the hot-plate response latency. These data emphasize that low threshold afferent input is likely subject to an ongoing modulation, the loss of which results in a miscoding of the afferent stimulus yielding a pain relevant message. The lack of effect of agents having a powerful effect on somatic pain stimuli and the converse effects of glutamate receptor antagonists on the strychnine hyperesthesia at doses which do not affect the somatic pain response indicate discriminable processing systems, the characteristics of which resemble the clinical phenomenon observed in patients suffering from sensory dysesthesia following central and peripheral horn injury.