Articles: hyperalgesia.
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Chronic pain is often associated with sensorimotor dysfunction but little is known about the early impact of limb fracture on sensory and motor performance. This exploratory study sought to assess these changes in patients with recent wrist and ankle fractures. A secondary aim was to determine the incidence of Complex Regional Pain Syndrome (CRPS) and its clinical features. ⋯ Limb fracture is associated with changes in pain perceptions, motor planning, and disruption to body perception. Signs and symptoms of CRPS, ongoing pain and delayed recovery post-fracture are common. WHAT DOES THIS STUDY ADD?: In the immediate post-fracture period: Body perception disturbance is reported in the fractured limb. Imagined movements of the fractured limb are less vivid and associated with pain This study contributes to the incidence literature on CRPS.
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The aim of this study was to assess differences in the levels of hyperalgesia and cutaneous allodynia (CA) among women with migraine, temporomandibular disorders (TMD), or both. ⋯ More pronounced levels of hyperalgesia and CA were found in patients with both TMD and migraine. Thus, it is suggested that the concomitant presence of TMD and migraine may be related to intensification of central sensitization.
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Aims Migraine and depression have a strong association. We aimed to determine whether this relationship was particularly evident in migraineurs with allodynia. Methods A cross-sectional study was carried out of 98 consecutive patients with episodic migraine presenting for their first evaluation in an outpatient clinic. ⋯ An increased severity of allodynia correlated with higher depression scores ( r = 0.224; p = 0.027). Conclusion Anxious and depressive symptoms are more common in migraineurs with allodynia than in those without allodynia. Further studies are necessary to clarify the relationship between depressive symptoms and allodynia, as well as its therapeutic implications in migraine.
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Macrophages play a role in innate immunity within the body, are located in muscle tissue, and can release inflammatory cytokines that sensitize local nociceptors. In this study we investigate the role of resident macrophages in the noninflammatory muscle pain model induced by 2 pH 4.0 preservative-free sterile saline (pH 4.0) injections 5 days apart in the gastrocnemius muscle. We showed that injecting 2 pH 4.0 injections into the gastrocnemius muscle increased the number of local muscle macrophages, and depleting muscle macrophages with clodronate liposomes before acid injections attenuated the hyperalgesia produced by this model. To further examine the contribution of local macrophages to this hyperalgesia, we injected mice intramuscularly with C34, a toll-like receptor 4 (TLR4) antagonist. When given before the first pH 4.0 injection, C34 attenuated the muscle and tactile hyperalgesia produced by the model. However, when given before the second injection C34 had no effect on the development of hyperalgesia. Then to test whether activation of local macrophages sensitizes nociceptors to normally non-nociceptive stimuli we replaced either the first or second acid injection with the immune cell activator lipopolysaccharide, or the inflammatory cytokine interleukin (IL)-6. Injecting LPS or IL-6 instead of the either the first or second pH 4.0 injection resulted in a dose-dependent increase in paw withdrawal responses and decrease in muscle withdrawal thresholds. The highest doses of LPS and IL-6 resulted in development of hyperalgesia bilaterally. The present study showed that resident macrophages in muscle are key to development of chronic muscle pain. ⋯ This article presents evidence for the role of macrophages in the development of chronic muscle pain using a mouse model. These data suggest that macrophages could be a potential therapeutic target to prevent transition of acute to chronic muscle pain particularly in tissue acidosis conditions.
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Endogenous opioid system dysfunction potentially contributes to chronic pain in fibromyalgia (FM), but it is unknown if this dysfunction is related to established neurobiological markers of hyperalgesia. We previously reported that µ-opioid receptor (MOR) availability was reduced in patients with FM as compared with healthy controls in several pain-processing brain regions. In the present study, we compared pain-evoked functional magnetic resonance imaging with endogenous MOR binding and clinical pain ratings in female opioid-naive patients with FM (n = 18) using whole-brain analyses and regions of interest from our previous research. ⋯ These findings are the first to link endogenous opioid system tone to regional pain-evoked brain activity in a clinical pain population. Our data suggest that dysregulation of the endogenous opioid system in FM could lead to less excitation in antinociceptive brain regions by incoming noxious stimulation, resulting in the hyperalgesia and allodynia commonly observed in this population. We propose a conceptual model of affective pain dysregulation in FM.