Pain
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Case Reports Comparative Study
Spinal cord lesion after long-term intrathecal clonidine and bupivacaine treatment for the management of intractable pain.
Long-term intrathecal drug administration using implanted pumps is increasingly used in the treatment of chronic refractory pain [Anderson and Burchiel 1999, Neurosurgery 44 (1999) 289; Krames 2002, Best Pract Res Clin Anaesthesiol 16 (2002) 619; Wallace 2002, Neurology 59 (2002) S18]. Extensive clinical experience over the last 15 years suggests that in selected cases the technique is safe, although infections, system malfunction and drug-related complications have been reported. In most cases, drug-related spinal cord injuries have resulted from the compression of a spinal inflammatory mass or abcess rather than from a direct neurotoxic effect. We report on a case of toxic spinal cord lesion occurring after more than 3 years of uneventful continuous infusion of a mixture of bupivacaine and clonidine.
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Comparative Study
Sex differences in temporal summation of pain and aftersensations following repetitive noxious mechanical stimulation.
Several studies demonstrate that women are more sensitive to experimental pain than men. In addition, women exhibit greater temporal summation of heat and mechanically evoked pain. Since temporal summation of pain is centrally mediated, its greater expression in women suggests a central nociceptive hyperexcitability relative to men. ⋯ Temporal summation of pain intensity and unpleasantness ratings were more pronounced in women than men (P<0.0001). In addition, significant temporal summation occurred only with 2 s interstimulus interval for men (P<0.0005) but with 2 and 5 s interstimulus interval for women (P<0.0001). Moreover, women provided greater ratings for the intensity and the unpleasantness of aftersensations (P<0.0005) and reported painful aftersensations at greater frequency (P<0.05) Greater temporal summation of pain and aftersensations in women suggests that their central processing of nociceptive input may be more easily upregulated into pathological hyperexcitability, possibly accounting for the higher prevalence of various chronic pain conditions among women.
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Comparative Study
Lessons learned from a multiple-dose post-operative analgesic trial.
Patients undergoing major surgery often require several days of post-operative analgesic management. However, little data are available on the course of post-operative pain during this period. Such data would be extremely helpful in planning treatment, formulating pain management guidelines, and determining how to construct multiple-dose post-operative analgesic clinical trials. ⋯ Only 9% of patients reported experiencing moderate-to-severe pain approximately 2 weeks later, at the end of the study. Describing pain as mild, moderate, or severe could be a simple, meaningful clinical trial outcome measure. Because most patients experience only mild pain 6 days after surgery, long-term clinical trials of post-operative pain control may be more efficient and cost-effective if they focus on the subset of patients with persistent moderate or severe pain.
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This experiment tested whether meaning influences the experience of pain. Thirty-one healthy students participated in a study on evaluations of various stimuli placed against the neck. ⋯ Confirming the hypothesis that tissue-damaging meaning influences the experience of pain, participants who were told that the bar was hot rated it as more painful than participants who were told that it was cold. Damage interpretations mediated the effect of information on pain intensity scores, which supported the theory that tissue-damage is a crucial aspect of meaning to influence the subjective intensity of pain.
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Comparative Study
Taxol-induced sensory disturbance is characterized by preferential impairment of myelinated fiber function in cancer patients.
Taxol produces neuropathic pain with three distinct zones of involvement in the extremities. Most distally is an area of on-going pain and proximal to this is a zone of sensory disturbance but not overt pain. These two areas were confined in all but one case to the glabrous skin of the hands and/or feet. ⋯ In contrast to mechanical sensibility, thermal thresholds for warm and heat pain detection were normal throughout. Finally, chemotherapy patients showed paradoxical burning pain to skin cooling that was most pronounced in proximal areas of skin thought to be unaffected by the patients, intermediate in the border zone of altered sensibility and least pronounced in areas of on-going pain. These data suggest that taxol produces a neuropathy characterized by pronounced impairment of function in A-beta myelinated fibers, intermediate impairment of A-delta myelinated fibers, and a relative sparing of C-fibers.