Articles: neuralgia.
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Randomized Controlled Trial Comparative Study Clinical Trial
Nortriptyline versus amitriptyline in postherpetic neuralgia: a randomized trial.
OBJECTIVE (BACKGROUND): Amitriptyline (AT) is a standard therapy for postherpetic neuralgia (PHN). Our hypothesis was that nortriptyline (NT), a noradrenergic metabolite of AT, may be more effective. ⋯ We concluded that this study provides a scientific basis for an analgesic action of NT in PHN because pain relief occurred without an antidepressant effect, and that although there were fewer side effects with NT, AT and NT appear to have a similar analgesic action for most individuals.
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Neurobiology of disease · Oct 1998
ReviewPostherpetic neuralgia: irritable nociceptors and deafferentation.
Postherpetic neuralgia (PHN) is a common and often devastatingly painful condition. It is also one of the most extensively investigated of the neuropathic pains. Patients with PHN have been studied using quantitative testing of primary afferent function, skin biopsies, and controlled treatment trials. ⋯ Other deafferentation patients have severe spontaneous pain without hyperalgesia or allodynia and presumably have lost both large and small diameter fibers. In this group the pain is likely due to increased spontaneous activity in deafferented central neurons and/or reorganization of central connections. These three types of mechanism may coexist in individual patients and each offers the possibility for developing new therapeutic interventions.
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We investigated the effect of intravenous magnesium, a N-methyl-D-asparate (NMDA) receptor antagonist, in 8 patients suffering from neuropathic pain (post herpetic neuralgia or causalgia etc.). After the nerve block, magnesium sulphate (0.5 mol.l-1) 5 ml was administered intravenously by bolus infusion taking 5 min, followed by continuous infusion of the same dose for one hour. All patients were treated with this therapy once a week. ⋯ Some patients felt heat sensation immediately after the bolus infusion of Mg, and had a good sleep after this therapy. However, there were not any severe side effects and significant change in HR or BP. We conclude that this therapy with magnesium once a week is safe and effective for relieving neuropathic pain.
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The effect of neuropeptide FF in the periaqueductal gray on pain behaviour was studied in rats with a chronic neuropathy induced by unilateral ligation of two spinal nerves. Neuropeptide FF produced in a non-monotonic fashion a significant attenuation of tactile allodynia. The antiallodynic effect was not significantly modulated by naloxone administered systemically or intracerebrally. ⋯ The results indicate that neuropeptide FF in the periaqueductal gray may produce a selective attenuation of tactile allodynia in neuropathic rats. This antiallodynic effect is at least partly independent of naloxone-sensitive opioid receptors. Furthermore, neuropeptide FF in the periaqueductal gray attenuates antinociception induced by intracerebrally but not systemically administered morphine.
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Recent evidence indicates that neuropathic pain from partial peripheral nerve injury is maintained by electrophysiologically abnormal signals from injured sensory neurons. To gain an insight into the mechanisms underlying this electrophysiological abnormality, we examined the effects of S1 spinal nerve transection on the membrane properties of S1 dorsal root ganglion neurons one to two weeks after injury. This injury produced significant action potential broadening [40% (1 ms) in C-, 149% (1.5 ms) in A delta- and 84% (0.5 ms) in A alpha/beta-cells], which was primarily due to the enhancement of the "shoulder" appearing on the falling phase of the action potential in C- and A delta-cells and the emergence of a shoulder in A alpha/beta-cells, and significant cell-type specific changes in the time-course of the rising phase of the action potential; i.e. an increase in rise time (A delta: 35%, 0.15 ms; A alpha/beta: 13%, 0.04 ms) and a decrease in the maximal rate of rise (A delta: 17%, 77 V/s; A alpha/beta: 13%, 79 V/s). ⋯ The nerve injury-induced reduction of rheobase was not accompanied by related change in input resistance or threshold potential in any of the cell populations. The present results indicate that chronic peripheral axotomy of dorsal root ganglion neurons, which gives rise to neuropathic pain, produces profound changes in the action potential waveform of dorsal root ganglion neurons in a cell type-specific fashion. Furthermore, the results suggest that the axotomy increases the excitability of dorsal root ganglion neurons not by altering input resistance (i.e. leak conductance) or threshold potential, but by increasing apparent input resistance near the resting membrane potential in A-cells and decreasing the resting membrane potential in C-cells.