Articles: hyperalgesia.
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Randomized Controlled Trial
Transcutaneous electrical nerve stimulation reduces pain, fatigue and hyperalgesia while restoring central inhibition in primary fibromyalgia.
Because transcutaneous electrical nerve stimulation (TENS) works by reducing central excitability and activating central inhibition pathways, we tested the hypothesis that TENS would reduce pain and fatigue and improve function and hyperalgesia in people with fibromyalgia who have enhanced central excitability and reduced inhibition. The current study used a double-blinded randomized, placebo-controlled cross-over design to test the effects of a single treatment of TENS with people with fibromyalgia. Three treatments were assessed in random order: active TENS, placebo TENS and no TENS. ⋯ No changes in functional tasks were observed with TENS. Thus, the current study suggests TENS has short-term efficacy in relieving symptoms of fibromyalgia while the stimulator is active. Future clinical trials should examine the effects of repeated daily delivery of TENS, similar to the way in which TENS is used clinically on pain, fatigue, function, and quality of life in individuals with fibromyalgia.
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Randomized Controlled Trial
Repeated intramuscular injections of nerve growth factor induced progressive muscle hyperalgesia, facilitated temporal summation, and expanded pain areas.
Intramuscular injection of nerve growth factor (NGF) is known to induce deep-tissue mechanical hyperalgesia. In this study it was hypothesised that daily intramuscular injections of NGF produce a progressive manifestation of soreness, mechanical hyperalgesia, and temporal summation of pain. In a double-blind placebo-controlled design, 12 healthy subjects were injected on 3 days with NGF into the tibialis anterior muscle and with isotonic saline on the contralateral side. ⋯ Compared with baseline and isotonic saline, the NGF injections caused (P<0.05): (1) progressively increasing soreness scores from 3 hours after the first injection until day 2, after which it remained increased; (2) decreased PPTs at days 1 to 3; (3) facilitated temporal summation of pressure pain at days 1 to 10; and (4) enlarged pressure-induced pain area after the injection on day 1 to day 6. The daily injections of NGF produced a progressive manifestation of muscle soreness, mechanical hyperalgesia, temporal summation of pressure pain, and pressure-induced pain distribution. These data illustrate that the prolonged NGF application affects peripheral and central mechanisms and may reflect process in musculoskeletal pain conditions.
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Randomized Controlled Trial
Acidic saline-induced pain as a model for experimental masseter myalgia in healthy subjects.
Repeated injection of acidic saline into skeletal muscles of the leg in rodents induces a prolonged bilateral mechanical hyperalgesia that persists for up to 30 days and may be useful to model widespread muscle pain conditions. In this study, repeated injection of acidic (pH 3.3) saline solution into the masseter muscle of healthy human subjects was undertaken to determine if these injections are painful and whether they would induce a prolonged period of muscle sensitization to artificial and/or natural mechanical stimulation of the masseter and temporalis muscles. ⋯ These findings indicate that, unlike in some rodent models, repeated injection of low pH solutions into jaw muscles of humans fails to induce a period of prolonged muscle hyperalgesia.
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Randomized Controlled Trial
Evaluation of the effects of a metabotropic glutamate receptor 5-antagonist on electrically induced pain and central sensitization in healthy human volunteers.
This study aimed to investigate the effect of a single dose of the mGluR5-antagonist AZD9272 on electrically induced pain, central sensitization and axon reflex flare. ⋯ Single doses of the centrally acting mGluR5-antagonist AZD9272 did not reduce C-fibre evoked pain, central sensitization or flare reaction.
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Randomized Controlled Trial
Intrathecal lentivirus-mediated transfer of interleukin-10 attenuates chronic constriction injury-induced neuropathic pain through modulation of spinal high-mobility group box 1 in rats.
Neuropathic pain is a complex state of chronic pain that is usually accompanied by peripheral and central nervous system damage or dysfunction. Previous studies have indicated that neuroinflammation in the spinal cord is an important contributor to neuropathological and behavioral abnormalities. A series of early inflammatory markers, such as IL-1, TNF-α, and IFN-γ, and advanced inflammatory markers, such as high-mobility group box 1 (HMGB1), are involved in neuroinflammation. ⋯ Our results indicate that intrathecal lentiviral-mediated transfer of IL-10 attenuates CCI-induced neuropathic pain in rats. The anti-thermal hyperalgesia and anti-mechanical allodynia may be partly attributable to the decreased expression of HMGB1 and inhibition of HMGB1-RAGE pathway.