Articles: hyperalgesia.
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For years, physical therapists have been utilizing a variety of modalities, including transcutaneous electrical nerve stimulation (TENS), in an attempt to manage pain associated with inflammation. However, the data on clinical effectiveness is conflicting and the neurophysiological mechanism of action is not known. The purpose of this study was to investigate the effects of high and low frequency TENS on the secondary hyperalgesia that occurs after joint inflammation. ⋯ There was no effect of TENS on spontaneous pain behaviors or joint swelling when compared to controls. Thus, TENS appears to be more effective in reducing referred pain (or secondary hyperalgesia) without affecting guarding or splinting of the affected limb. Thus, clinically, the choice to use TENS may depend on patient symptoms; specifically TENS should be effective in reducing referred or radiating pain.
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The present study examined the effects of intrathecal (i.t.) treatment (twice-daily injections on post-operative (PO) days 0-8) with the metabotropic glutamate receptor (mGluR) compound, (S)-4-carboxyphenylglycine ((S)-4CPG), or the non-competitive N-methyl-D-aspartate (NMDA) antagonist, dizocilipine maleate (MK-801), on mechanical allodynia and cold hyperalgesia associated with chronic constriction injury (CCI) of the sciatic nerve in rats. Also, the effects of early (twice-daily injections on days 0-3) or late (twice-daily injections on days 8-11) (S)-4CPG treatment on the injury-related mechanical allodynia and cold hyperalgesia were assessed in CCI rats. ⋯ However, late treatment with (S)-4CPG did not reduce the nociceptive behaviours in either behavioural task. These data not only confirm that the NMDA receptor plays a role in chronic nociception, but also suggest that Group I mGluRs are more critically involved in the development, and not the maintenance, of mechanical allodynia and cold hyperalgesia associated with CCI in rats.
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The veterinary journal · Jul 1998
The influence of lesion type on the duration of hyperalgesia associated with hindlimb lameness in dairy cattle.
The nociceptive thresholds of 42 sound dairy cattle were compared with 53 animals displaying hind-claw lameness. All animals in the study were lameness scored and nociceptive threshold tested. Each animal then received a routine claw trim while the lame cattle also had the cause of lameness determined and treated. ⋯ The group which were retested on day 28 were subdivided by lesion type: sole ulcer; white line disease and acute digital tissue infection. Each lesion type caused a decreased nociceptive threshold at day 1. At re-evaluation on day 28 only the thresholds of the acute digital tissue infection group were not significantly different from the sound group but thresholds in sole ulcer and white line disease cows were still depressed.
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The current study aimed to assess whether local administration of morphine could block the development of hyperalgesia and allodynia in a rat model of osteotomy or bone damage. ⋯ This study shows that local application of a low dose of morphine effectively blocks the development of hyperalgesia and allodynia in a rat model of bone damage through mu-opioid receptor action. These findings provide further evidence that local application of morphine at the time of orthopedic surgery, bone graft, or bone marrow harvesting may reduce the amount of postoperative pain.
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The influence of midthoracic spinalization on thermally and mechanically induced spinal withdrawal reflex responses was studied in the rat. There were three experimental groups of rats: healthy controls, rats with a spinal nerve ligation-induced unilateral neuropathy, and rats with a carrageenan-induced inflammation of one hindpaw. Tail flick response was induced by radiant heat. ⋯ In contrast, spinal withdrawal responses induced by noxious cold or mechanical stimulation were significantly suppressed following spinalization. The spinalization-induced facilitatory effects as well as inhibitory ones on spinal reflexes were enhanced in inflamed/neuropathic animals. The results indicate that the tonic descending control of spinal nocifensive responses varies depending on the submodality of the test stimulus, the segmental level of the reflex (tail vs. hindlimb), and on the pathophysiological condition.