Articles: chronic-pain.
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Disregarding pain resulting from vitamin deficiency, an analgesic effect seems to be exerted only by vitamin B1 (thiamine), vitamin B6 (pyridoxines), and vitamin B12 (cobalamine), particularly when the three are given in combination. The analgesic effect is attributed to an increased availability and/or effectiveness of noradrenaline and 5-hydroxytryptamine acting as inhibitory transmitters in the nociceptive system. In animal experiments, high doses of these vitamins administered alone or in combination inhibited nociceptive behavior and depressed the nociceptive activity evoked in single neurons of the dorsal horn of the spinal cord and in the thalamus. ⋯ The use of high doses of vitamin B6 may be limited by a neurotoxic effect. The effectiveness of B vitamins in depressing chronic pain has not been established. It would be interesting to know if the B vitamins are of use as adjuvants in the treatment of tumor pain.
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Epidural spinal cord stimulation (SCS) has gained a secure place in the armamentarium of the surgeon treating chronic pain conditions (1, 2). The complexity of the intraspinal structures and their different susceptibility to electrical signals, however, has made it difficult to characterize the effects of the stimulation, Some important recent work has helped shed light on the electrical properties of the intraspinal structures and on the electrical field potentials generated with epidural spinal cord stimulation. This work, initially pioneered by Sin and Coburn, has successfully been expanded and perfected by Holsheimer and Strujik at the University of Twente, The Netherlands (3-8). ⋯ The model can simulate the effects of epidural stimulation with different electrode geometries and configurations (8). The data generated from the model were then validated by comparing them to a large number of data collected by the author in implanted subjects (9-12). The author also conducted a detailed analysis of the clinical properties of the activation of the intraspinal structures at various electrode positions in the spine (13, 14).
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Objective. In addition to treatment of refractory chronic pain in patients with peripheral vascular disease, dorsal spinal cord stimulation (DCS) increases cutaneous blood flow to the extremities and may have a limb-saving effect. The purpose of this study was to examine the role of the sympathetic nervous system in the cutaneous vasodilation due to DCS. ⋯ Propranolol (5 mg/kg, i.v.), a nonselective beta-adrenergic receptor antagonist, attenuated the DCS response while adrenal demedullation did not. Conclusion. Overall, our results show that DCS-induced vasodilation can occur through mechanisms that are independent of sympathetic outflow.
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The transdermal therapeutic system (TTS) for fentanyl is a drug-delivery system for use in patients with chronic pain who require an opioid analgesic. A multicentre, randomized, double-blind, placebo-controlled study was performed to evaluate the efficacy and safety of TTS-fentanyl as an analgesic for chronic cancer pain. One hundred and thirty-eight patients entered a 15-day dose-titration period, followed by a 9-day double-blind period (95 patients) with TTS-fentanyl or placebo. ⋯ Due to an unexpectedly high placebo response it was not possible to demonstrate fentanyl to be statistically superior to placebo. This may reflect the practical difficulties of performing clinical trials in cancer patients with great inter-individual variability. Copyright 1998 European Federation of Chapters of the International Association for the Study of Pain.
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Peripheral nerve injury may lead to neuropathic pain that has been considered unresponsive to opioids. In animal models of neuropathic pain, there are previous data of both increased and decreased effect of opioids, but only limited information of the long-term effects of opioid treatment on the development of the symptoms of neuropathy. The possibility of preventing the development of signs of neuropathy with either a single pre-injury injection or chronic postinjury administration of morphine was studied in rats with unilateral peripheral neuropathy due to tight ligation of the L5 and L6 spinal nerves. ⋯ No autotomy, signs of distress, altered social behaviour or morphine withdrawal was seen in any of the rats. The fact that neuropathic pain-like symptoms were not attenuated by any of the treatments studied could indicate that neither premedication nor postoperative pain management with systemic morphine is effective in preventing postoperative neuropathic pain. Copyright 1998 European Federation of Chapters of the International Association for the Study of Pain.