Articles: neuralgia.
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Post-herpetic neuralgia (PHN) is the most common complication of herpes zoster (HZ, shingles), particularly in the elderly and those with severe acute phase symptoms. Unless or until varicella vaccination reduces the incidence of HZ and attenuates the risk and/or severity of complications, PHN will continue to result in patient suffering and remain a significant cause of healthcare and social support resource consumption. There have been useful advances in PHN management (e.g. use of the anticonvulsant gabapentin and topical local anaesthetic patches), but some cases remain intractable. ⋯ Other acute interventions require further evaluation (nerve blocks, acute phase use of tricyclic antidepressants or anticonvulsants). As prevention of PHN requires early recognition and prompt management of at-risk patients presenting with acute HZ, public education and provision of information to relevant healthcare personnel are important. This article discusses issues relevant to PHN management and prevention, and provides a review of the pertinent literature.
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An altered glutamatergic transmission within the central nervous system is supposed to be involved in the generation and propagation of neuropathic pain. Results from experimental studies with animal models of neuropathic pain demonstrate that glutamate antagonists have a positive effect on various parameters. Clinical studies with the NMDA-receptor antagonists ketamine, amantadine, memantine and dextromethorphan and with the antiepileptics gabapentin and lamotrigine, which reduce presynaptic release of glutamate,have been performed. ⋯ Important side effects of the NMDA receptor antagonists are hallucination and agitation, whereas tiredness and dizziness are the ones of the antiepileptics. Till now, glutamate antagonists are not drugs of first choice for the treatment of neuropathic pain. However, they are an effective alternative in case the established drugs are not helpful or are not tolerated well.
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There have been 4 recent major advances in the treatment of postherpetic neuralgia (PHN) that are based on the results of randomized, controlled trials. These advances are the demonstrations that gabapentin, the lidocaine patch 5%, and opioid analgesics are efficacious in patients with PHN, and the report that nortriptyline and amitriptyline provide equivalent analgesic benefits for patients with PHN but that nortriptyline is better tolerated. ⋯ Despite these treatment advances, many patients remain refractory to current therapy, and the prevention of PHN has therefore become an important focus of current research. Research on administration of the varicella-zoster vaccine to prevent herpes zoster and on treatment of patients who have herpes zoster with combined antiviral and analgesic therapy to prevent PHN is discussed.