Pain
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Case Reports Comparative Study
Central post-stroke pain--a study of the mechanisms through analyses of the sensory abnormalities.
The somatosensory abnormalities in 20 men and 7 women (mean age 67 years, range 53-81) with central post-stroke pain (CPSP) have been analysed in detail with traditional neurological tests and quantitative methods. The cerebrovascular lesions were located in the lower brain-stem in 8 patients, involved the thalamus in 9 and in 6 were suprathalamic. In 4 patients the location of the CVL could not be determined. ⋯ The results indicate that all patients with CPSP have lesions that affect the major pathways for temperature and pain sensibility, i.e., the spino-thalamo-cortical pathways. Furthermore it appears that neither the level of the lesion along the neuraxis nor concomitant injury to the medial lemniscal pathways is crucial for the development of CPSP. The results confirm the notion that CPSP is a deafferentation syndrome, but they also provide evidence against the hypothesis that CPSP is a release phenomenon caused by a lesion that removes inhibitory influences of the lemniscal pathways on neurones that evoke pain.
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Fifty-six consecutive patients with pain due to cancer were admitted to a prospective study designed to test a clinical staging system for cancer pain. The system classifies patients in stage 1 (good prognosis) to stage 3 (poor prognosis) according to the mechanism of pain, characteristics of pain, previous narcotic exposure, cognitive function, psychological distress, tolerance and past history of drug addiction or alcoholism. During day 1 patients were staged after being seen by one of the investigators. ⋯ Eighteen of 22 patients in stage 1 achieved good pain control (82%) vs. 2/22 patients in stage 3 (10%; P less than 0.01). Sensitivity, specificity and negative predictive value of the system were 0.75, 0.86 and 0.80, respectively. We conclude that this is a simple and reliable system for clinical staging that can be used for clinical research and management of patients with cancer pain.
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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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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.
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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.