Current pain and headache reports
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Curr Pain Headache Rep · Feb 2003
ReviewOpioid resistance in chronic daily headache: a synthesis of ideas from the bench and bedside.
Chronic daily headache is a complex pain disorder that encompasses many diagnostic and therapeutic challenges. Our understanding of the pathophysiologic processes of intermittent migraine has improved over the past decade, but the biologic basis of chronic daily headache remains obscure. ⋯ Current concepts of the pathophysiologic basis of chronic pain and associated neural plasticity may elucidate a biologic basis for the general inefficacy of opioids in the management of chronic daily headache. This article explores the models of pathophysiology for migraine and chronic daily headache, the concept of chronic daily headache as a neuropathic pain syndrome, neural plasticity in the context of neuropathic pain states, the physiologic basis for opioid tolerance and opioid-induced hyperalgesia, and how each of these conditions interact to provoke the general lack of opioid efficacy often observed in the management of chronic daily headache.
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Curr Pain Headache Rep · Feb 2003
Review Comparative StudyAntidepressants for chronic neuropathic pain.
Tricyclic antidepressants have been used to manage pain for several decades, and are superior treatments for some patients suffering from neuropathic pain. Unfortunately, older antidepressants have dose-limiting side effects that can lead to drug intolerance. The most common are anticholinergic side effects, although some patients experience sexual dysfunction. ⋯ Taking an overdose of tricyclic antidepressants can be lethal in overdose. Several weeks of therapy may be required before antinociception occurs, but tricyclic antidepressants in optimal doses appear to be the most effective treatment for neuropathic pain; this is supported by systematic reviews comparing them with other agents. Newer medications such as atypical antidepressants and anticonvulsants may be overtaking older antidepressants, but they should not be overlooked as important options for the management of pain.
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Antidepressants, particularly tricyclic antidepressants, have been a mainstay in the prophylactic therapy of migraine. The tricyclic antidepressants amitriptyline, nortriptyline, and doxepin have been the major agents for prophylactic treatment of migraine. ⋯ The high-affinity selective serotonin reuptake inhibitors and other newer antidepressants have been disappointing and much less effective in the treatment of migraine. In patients who are depressed with severe migraine, a tricyclic antidepressant may treat both conditions; however, the addition of a newer atypical antidepressant may be needed.
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A greater understanding of the mechanisms that produce chronic pain states has led to a search for novel agents with the potential to produce analgesia by directly modulating specific processes involved in the transduction, transmission, modulation, perception, and encoding of pain. It is hoped that compounds directed at these specific targets will produce better analgesics with an improved side-effect profile. ⋯ In addition, these compounds have demonstrated the ability to prevent the development of tolerance to opioid analgesic therapy. This has led to investigations of therapies that combine an opioid agonist with an N-methyl-D-aspartate receptor antagonist.