Articles: hyperalgesia.
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J Pain Palliat Care Pharmacother · Jan 2011
ReviewChronic pain and surgery: a review of new insights from sensory testing.
Chronic pain is increasingly recognized as an undesirable outcome after surgery. Predicting risk of postoperative chronic pain, as well as chronic pain prevention or treatment, requires understanding of the processes underlying its development. Quantitative sensory testing research over the last decade has made it possible to start understanding the alterations in central pain processing associated with chronic pain and its development. ⋯ Preoperatively, hyperalgesia and poor descending inhibitory modulation appear to increase the risk of subsequent chronic pain. Postoperatively, abnormal persistence and spread of hyperalgesia, compatible with rostral neuraxial spread of central sensitization, are increasingly linked to the development and progression of chronic pain. These findings, which need further confirmation, suggest that perioperative quantitative sensory testing of pain sensitivity and pain modulation has the potential to become a valuable clinical tool for assessing risk of chronic pain development and for managing its prevention and treatment.
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Fibromyalgia syndrome (FM) is a highly prevalent musculoskeletal disorder that is often accompanied by somatic hyperalgesia (enhanced pain from noxious stimuli). Neural mechanisms of somatic hyperalgesia have been analyzed via quantitative sensory testing of FM patients. ⋯ FM pain is likely to be at least partially maintained by peripheral impulse input from deep tissues. This conclusion is supported by results of several studies showing that injection of local anesthetics into painful muscles normalizes somatic hyperalgesia in FM patients.
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Opioids are the most potent drugs for treatment of acute and chronic pain. However, accumulating evidence suggests that opioids may paradoxically also enhance pain, often referred to as opioid-induced hyperalgesia. Opioid-induced hyperalgesia is defined as an increased sensitivity to pain or a decreased pain threshold in response to opioid therapy. ⋯ However, it remains unclear whether opioid-induced hyperalgesia develops during continuous chronic application of opioids or on their withdrawal. This review provides a comprehensive summary of clinical research concerning opioid-induced hyperalgesia and the molecular mechanisms of opioid withdrawal and opioid tolerance and other potential mechanisms which might induce hyperalgesia during opioid therapy will be discussed. The status quo of our knowledge will be summarized and the clinical relevance of opioid-induced hyperalgesia will be discussed.
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Opioids are commonly used for pain control; however, they can cause hyperalgesia. The reason why this can happen is not known. The objective of this review was to describe the mechanisms, factors implicated, and drug modulation. ⋯ This is a very complex subject, which involves a series of pathophysiological mechanisms that could contribute for OIH and patient discomfort, bringing disastrous consequences.
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To review mechanisms that might contribute to sensory disturbances and sympathetically-maintained pain in complex regional pain syndrome (CRPS). ⋯ Sympathetic neural activity might contribute to pain and sensory disturbances in CRPS by feeding into nociceptive circuits at the site of injury or elsewhere in the CRPS-affected limb, within the dorsal horn, or via thalamo-cortical projections.