Articles: neuropathic-pain.
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To review the pathophysiology of fibromyalgia syndrome. ⋯ Multiple abnormal findings in fibromyalgia patients strongly indicate a neuropathic pain syndrome, reminiscent of complex regional pain syndrome or postherpetic neuralgia. In addition, fibromyalgia syndrome seems to share similar characteristics with these neuropathic pain syndromes, including ineffective response to many analgesics.
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Mexilitine is an anti-arrhythmic agent used to treat neuropathic pain. The drug has a low side-effect profile with gastritis as the predominant complaint. The following two cases suggest that mexilitine can potentially cause persistent ophthalmic changes and should be used with caution in chronic pain patients with preexisting ocular disease.
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Pain may begin in the periphery with activation of nociceptor transducers. The present article reviews the pharmacology of drug action at the level of the primary afferent by discussing the following: [1] agents which block transduction processes (vanilloids, sodium ion channel blockers, antiserotonergic agents, antipurinergic agents); [2] agents inhibiting the transducer site (opioids, cannabinoids, alpha adrenergic agents); [3] agents blocking transducer-based modulation processes (anti-inflammatories, antikinin agents, antitachykinins); and [4] agents which block primary afferent-related modification processes (antineurotrophins). There is a clear role for many of these agents in the treatment of inflammatory pain and they have potential benefits for neuropathic pain with peripheral triggers.
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This case study describes the therapeutic result of intrathecal administration of ziconotide, a new synthetic neurotoxin derived from the venom of the Philippine marine snail, Conus Magus, to a 48-year-old male with chronic, and previously untreatable, neuropathic pain of an undeterminable etiology. The patient suffered tactile allodynia and reported his baseline pain intensity to be 80 mm on the 100 mm Visual Analog Scale for Pain Intensity. ⋯ Currently, the patient rates his pain at 16 mm and enjoys an improved quality of life. This result suggests that treatment with ziconotide may provide outstanding relief to patients with chronic pain while sparing them the unpleasant side effects associated with other treatments.
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Chronic-constriction injury (CCI) of the sciatic nerve causes mechanical and heat hyperalgesia and mechanical allodynia in the plantar surface of the hindpaw. The underlying mechanism thought to account for these phenomena include central sensitization induced by peripheral nerve injury, ie, the increase in neuronal activity of spinal dorsal horn neurons. As a marker of neuronal activation of the central nervous system, Fos expression has been used widely to monitor the change in neuronal activity evoked by peripheral input. ⋯ The number of noxious stimulus-evoked Fos-labeled neurons in both the superficial and deep laminae of the dorsal horn in the CCI rats was increased significantly compared with those in sham-operated rats, suggesting an increased excitability of dorsal horn neurons to noxious stimuli. Concurrent EA treatment to the Zusanli point with the pinch stimulus suppressed the increase in the number of Fos-labeled cells in the spinal dorsal horn in the CCI rats. The present results show that EA treatment has antinociceptive effects on both pain behavior and neuronal activation of the spinal dorsal horn neurons in CCI rats.