Articles: hyperalgesia.
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To determine the presence of widespread pressure hyperalgesia in multiple sclerosis (MS) patients with and without pain and its association with pain and fatigue. ⋯ Our study found widespread pressure pain hyperalgesia in individuals with MS as compared with pain-free controls. No differences existed between MS patients with pain and those without pain in the presence of widespread pressure sensitivity. Current results suggest that MS is associated with sensory hyperexcitability of the central nervous system or dysfunction in endogenous pain modulatory systems.
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Randomized Controlled Trial
Failure of intrathecal ketorolac to reduce remifentanil-induced postinfusion hyperalgesia in humans.
In rodents, acute exposure to opioids results in transient antinociception followed by longer lasting hypersensitivity to tactile or thermal stimuli, a phenomenon termed opioid-induced hyperalgesia. This hypersensitivity can be blocked or reversed by intrathecally administered cyclooxygenase inhibitors, including ketorolac, suggesting a role for spinal prostaglandins. In surgical patients, the dose of intraoperative opioid, particularly the short-acting drug, remifentanil, is directly related to increased pain and opioid requirements for many hours postoperatively. ⋯ The primary outcome measure, area of capsaicin-induced hypersensitivity after stopping remifentanil, showed a similar increase in those receiving ketorolac as in those receiving saline. Cerebrospinal fluid prostaglandin E2 concentrations did not increase during postinfusion hyperalgesia compared with those during infusion, and they were not increased during infusion compared with those in historical controls. These data fail to support the hypothesis that acute opioid-induced hyperalgesia reflects spinal cyclooxygenase activation causing central sensitization.
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Fibromyalgia (FMS) and high frequency episodic/chronic migraine (M) very frequently co-occur, suggesting common pathophysiological mechanisms; both conditions display generalized somatic hyperalgesia. In FMS-M comorbidity we assessed if: a different level of hyperalgesia is present compared to one condition only; hyperalgesia is a function of migraine frequency; migraine attacks trigger FMS symptoms. ⋯ Co-morbidity between fibromyalgia and migraine involves heightened somatic hyperalgesia compared to one condition only. Increased migraine frequency - with shift towards chronicity - enhances both hyperalgesia and spontaneous FMS pain, which is reversed by effective migraine prophylaxis. These results suggest different levels of central sensitization in patients with migraine, fibromyalgia or both conditions and a role for migraine as a triggering factor for FMS.
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Spinal nerve L5/L6 ligation (SNL) in rats has become the standard for mechanistic studies of peripheral neuropathy and screening for novel analgesics. Conventional SNL in our hybrid mice resulted in a wide range of allodynia. Anatomical evaluation indicated that a variable number of lumbar vertebrae existed, resulting in L4/L5 or L5/L6 being ligated. ⋯ Ligation of mouse L4 and L5 spinal nerves produces consistent, robust neuropathic pain behaviors and is suitable as a model for investigating mechanisms of neuropathic pain and for testing of novel analgesics. Gabapentin, used as a validation drug in neuropathic pain models and as a reference compound for novel analgesics, significantly reduced allodynia in the mice tested (L4/L5 ligations). Given the ease of surgery, robust allodynia, and larger von Frey sensitive area, we conclude that combined ligation of spinal nerves L4 and L5 optimizes the SNL model in mice.
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Chronic pain is the most common and disabling feature of endometriosis. Surgical excision of endometriosis lesions provides relief but pain relapse is common. Studies in a preclinical model of endometriosis might help to unravel the role of the ectopic lesions as the source of pain. Thus, we evaluated the impact of lesion excision on mechanical hyperalgesia in a preclinical model of endometriosis pain. ⋯ In this preclinical model, we demonstrate that endometriosis pain is alleviated by surgical excision of the ectopic lesion or drainage of its cysts, providing support for the clinical observation that endometriosis pain is dependent upon the ongoing presence of the lesions.