Metabolism: clinical and experimental
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Intractable pain may require neurosurgical intervention. This review provides a critical update of neurosurgical techniques available to treat this condition. Neurosurgery can affect pain's pathways from the receptor up to the "centers" of its reception and perception, either by destroying or by stimulating them. ⋯ The indications for undertaking an ablative vs a neurostimulative procedure, as well as selection of the anatomical target, depend largely on whether pain is nociceptive or neuropathic, given that most of these indications overlap to some extent. In addition, because the published outcomes are not based on universal criteria, it is difficult for the attending physician to select the type of procedure most suitable to the pain problem. This brief review surveys the various neurosurgical procedures together with their corresponding indications in the hope that the information provided will help practitioners choose (1) the type of neurosurgical therapy most appropriate to their patients' needs and (2) the neurosurgical group best equipped to implement that choice.
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Arthritic pain and disability are at or near the top of the list of reasons adult patients seek medical attention. At least 47.8 million US residents have arthritis. In Europe, the magnitude of the problem is similar, affecting 8 million in the United Kingdom and 108 million across the continent. ⋯ Analysis of joint fluid is mandatory to rule out septic arthritis, which can rapidly become lethal. Because of its special ability to identify and quantitate urate deposits in peripheral tissues, dual-energy computed tomography should prove valuable in the differential diagnosis of gout. Gout mimics a variety of illnesses; for example, spinal gout may masquerade as metastatic cancer, epidural abscess, and nerve compression syndrome.
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Women have a higher prevalence than men of several clinical pain conditions and of inflammation-mediated disorders. There is also increasing evidence for sex differences in sensitivity to experimental pain and in the response to analgesics. Estrogen, progesterone, and other gonadal hormones have a complex role in inflammatory processes and the pain response. ⋯ These nutritional interventions, which influence cytokine, leukotriene, and prostaglandin pathways, may be of particular benefit to women due to their higher prevalence of inflammatory chronic pain disorders. The recent launch of a new large-scale randomized trial of these nutritional supplements provides an opportunity to assess their potential antinociceptive role. Additional research is needed to clarify the mechanisms for sex differences in pain and to develop new treatment modalities that improve pain management for both men and women.
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Review
Fibromyalgia and the complex regional pain syndrome: similarities in pathophysiology and treatment.
Although the pain of fibromyalgia usually is not preceded by an injury to the involved tissue, whereas that of the complex regional pain syndrome usually starts at a site of prior trauma or surgery, both disorders may share a common mechanism-pathologic sensitization of brain mechanisms that integrate nociceptive signals-and both apparently respond to treatment with ketamine, an anesthetic-analgesic agent whose actions include blockade of N-methyl-D-aspartate receptors. Ketamine's widespread illegal use as a recreational agent probably precludes developing it as a general treatment of centrally mediated pain disorders; however, its efficacy suggests that related, to-be-discovered agents could be useful.
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Therapeutic management of chronic pain has not been widely successful owing to a lack of understanding of factors that initiate and maintain the chronic pain condition. Efforts to delineate the mechanisms underlying pain long have focused on neuronal elements of pain pathways, and both opiate- and non-opiate-based therapeutics are thought largely to target neurons. Abnormal neuronal activity at the level of spinal cord "pain centers" in the dorsal horn leads to hypersensitivity or a hyperalgesic response subsequent to the initial painful stimulus. ⋯ Recent evidence even suggests that opioid tolerance and withdrawal hyperalgesia may be initiated and maintained via actions of microglia and astroglia. Together, these recent findings suggest that glia will serve as novel therapeutic targets for the treatment of chronic pain. To fully exploit glia as novel therapeutic targets will require a greater understanding of glial biology, as well as the identification of agents able to control the glial reactions involved in chronic pain, without interfering with beneficial glial functions.