The journal of pain : official journal of the American Pain Society
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The objective of this article is to provide an overview of the natural history and treatment of herpes zoster, with a focus on pain management. Herpes zoster has the highest incidence of all neurological diseases, occurring annually in approximately 1 million people in the United States. A basic feature of herpes zoster is a marked increase in incidence with aging and with diseases and drugs that impair cellular immunity. Herpes zoster begins with reactivation of varicella zoster virus in dorsal root or cranial nerve ganglia, which is often accompanied by a prodrome of dermatomal pain or abnormal sensations. Varicella zoster virus spreads in the affected primary afferent nerve to the skin and produces a characteristic dermatomal maculopapular and vesicular rash and pain. Herpes zoster acute pain lowers quality of life and interferes with activities of daily living. Antiviral therapy and scheduled analgesics form the pharmacotherapeutic foundation for herpes zoster acute pain reduction. If moderate to severe herpes zoster pain is not adequately relieved by antiviral agents in combination with oral analgesic medications, then corticosteroids, anticonvulsants (eg, gabapentin or pregabalin), tricyclic antidepressants (eg, nortriptyline or desipramine), or neural blockade can be considered. ⋯ This article presents information on the clinical features and treatment of herpes zoster. This information will help clinicians diagnose and manage herpes zoster pain.
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The heat pain threshold was assessed in 32 healthy participants after a mild burn on the dorsal surface of each hand, after injection of an opioid antagonist (80 microg naloxone) or vehicle alone (0.2 mL saline) into the burnt skin of 1 hand, and after repeated painful immersion of this hand in cold water for up to 180 seconds. We hypothesized that sensitivity to heat would decrease at the burn-injured site after the immersions, due to local release of opioids into the burnt skin. Naloxone augmented cold-induced pain during the immersions in participants who tolerated the longest immersions, implying that release of endogenous opioids suppressed cold-pain. After the immersions, sensitivity to heat decreased at the burn-injured site in the immersed hand, but naloxone did not block this effect. Instead, naloxone altered sensitivity to heat in unburnt skin, implying that thermal hyperalgesia at sites of burn injury masked the modulatory effects of opioids. In particular, naloxone blocked a decrease in sensitivity to heat at an unburnt site on the contralateral hand of participants who tolerated the longest immersions, consistent with central or systemic opioid release. Naloxone reduced sensitivity to heat at unburnt sites in participants who tolerated medium-length immersions, suggesting that an increase in systemic or central opioid activity evoked thermal hyperalgesia in this group. In addition, in a small group of participants who tolerated only brief immersions, naloxone blocked decreases in sensitivity to heat at an unburnt site in the immersed hand. These findings suggest that repeated painful immersions trigger local opioid release in participants who tolerate only brief immersions, and elicit central or systemic opioid release in participants who tolerate longer immersions. ⋯ This article demonstrates that repeated immersion of the hand in painfully cold water increases opioid activity and that the increase in opioid activity exerts multiple opposing effects on sensitivity to heat. Individual differences in the response to opioids might contribute to individual differences in pain tolerance.
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Hypogonadotrophic hypogonadism is characteristically induced in men by intrathecal, transdermal, or sustained-action opioids. Although women receiving intrathecal opioids have similar changes, often accompanied by amenorrhea, hypogonadotrophic hypogonadism has not been documented in women receiving sustained-action, transdermal, or oral opioids. Dehydroepiandrosterone sulfate deficiency, indicating adrenal inhibition, is present in most men and women chronically consuming sustained-action oral or transdermal opioids. We recorded menstrual histories and measured gonadotrophin, androgen, and estradiol levels in 47 women ages 30 to 75 years who were consuming sustained-action oral or transdermal opioids for control of nonmalignant pain and in 68 non-opioid-consuming control subjects. Testosterone, estradiol, and dehydroepiandrosterone sulfate values were 48% to 57% lower in opioid-consuming women with intact ovarian tissue than in control subjects (P < .01-.05). Luteinizing hormone and follicle-stimulating hormone values averaged 30% lower in premenopausal and 70% lower in postmenopausal opioid consumers (P < .001). Among oophorectomized women not consuming estrogen, free testosterone levels were 39% lower in opioid consumers (P < .05), indicating impaired adrenal androgen production. Additional lowering of free testosterone levels was associated independently with oral estrogen replacement and low body mass index. Menses had often ceased soon after beginning sustained-action opioid therapy. Our observations document hypogonadotrophic hypogonadism plus decreased adrenal androgen production in most women consuming sustained-action oral or transdermal opioids. ⋯ These observations demonstrate profound inhibition of ovarian sex hormone and adrenal androgen production among women chronically consuming sustained-action opioids. Related consequences include altered menstrual flow, probable reduced fertility, and possible contributions to opioid-associated depression, osteoporosis, and hyperalgesia. Measurements of bone density, estradiol, and free testosterone may guide appropriate therapy.
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Opiate analgesic tolerance is defined as a need for higher doses of opiates to maintain pain relief after prolonged opiate exposure. Though changes in the opioid receptor undoubtedly occur during conditions of opiate tolerance, there is increasing evidence that opiate analgesic tolerance is also caused by pronociceptive adaptations in the spinal cord. We have previously observed increased glutamate release in the spinal cord dorsal horn of neonatal rats made tolerant to the opiate morphine. In this study, we investigate whether spinal substance P (SP) and its receptor, the neurokinin 1 (NK1) receptor, are also modulated by prolonged morphine exposure. Immunocytochemical studies show decreased SP- and NK1-immunoreactivity in the dorsal horn of morphine-treated rats, whereas SP mRNA in the dorsal root ganglia is not changed. Electrophysiological studies show that SP fails to activate the NK1 receptor in the morphine-treated rat. Taken together, the data indicate that chronic morphine treatment in the neonatal rat is characterized by a loss of SP effects on the NK1 receptor in lamina I of the neonatal spinal cord dorsal horn. The results are discussed in terms of compensatory spinal cord processes that may contribute to opiate analgesic tolerance. ⋯ This article describes anatomical and physiological changes that occur in the spinal cord dorsal horn of neonatal rats after chronic morphine treatment. These changes may represent an additional compensatory process of morphine tolerance and may represent an additional therapeutic target for the retention and restoration of pain relief with prolonged morphine treatment.
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Comment Letter Case Reports
Complex regional pain syndrome-a multifaceted disorder requiring multidimensional care: case study.