Neuroscience letters
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Neuroscience letters · Dec 2001
Contact heat evoked potentials as a valid means to study nociceptive pathways in human subjects.
Contact heat evoked potentials (CHEPs) have been difficult to elicit due to slow temperature rise times. A recently developed heat-foil technology was used to elicit pain and CHEPs. Two groups of subjects were separately stimulated at the left arm with contact heat via one fast-acting (70 degrees C/s) heat-foil thermode. ⋯ Consistent statistical values in the peak latencies and amplitudes were noted between consecutive investigations. The correlation between the pain intensity ratings and the major Cz/P750 amplitudes was highly significant in each study. Our validity tests suggested CHEPs to be useful for research and clinical applications in studying human pain activation related to thermal and nociceptive pathways.
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Neuroscience letters · Nov 2001
Shock wave application to rat skin induces degeneration and reinnervation of sensory nerve fibres.
There have been several reports on the use of extracorporeal shock waves in the treatment of pseudarthrosis, calcifying tendinitis, and tendinopathies of the elbow. However, the pathomechanism of pain relief has not been clarified. To investigate the analgesic properties of shock wave application, we analyzed whether it produces morphologic changes in cutaneous nerve fibres. ⋯ There was nearly complete degeneration of epidermal nerve fibres in the shock wave-treated skin, as indicated by the loss of immunoreactivity for PGP 9.5 or CGRP. Reinnervation of the epidermis occurred 2 weeks after treatment. These data show that relief of pain after shock wave application to the skin results from rapid degeneration of the intracutaneous nerve fibres.
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Neuroscience letters · Oct 2001
Prefrontal cortical hyperactivity in patients with sympathetically mediated chronic pain.
Chronic pain continues to impose a large burden of suffering, yet its neural correlates remain poorly understood. In sympathetically mediated chronic pain (SMP), peripheral sympathetic blockade temporarily relieves this pain, so that related neural activity can be studied without perturbing sensory inputs. ⋯ Ineffective sympathetic blocks, i.e. blocks that did not diminish the SMP pain, did not change the cortical responses to the painful thermal stimulus; while effective placebo resulted in similar responses to those of effective blocks. These findings provide evidence for abnormal brain responses to pain in patients with chronic SMP, which engages prefrontal/limbic networks more extensively than in acute pain-states.
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Neuroscience letters · Oct 2001
Conduction velocity of the spinothalamic tract in humans as assessed by CO(2) laser stimulation of C-fibers.
We measured the conduction velocity (CV) of C-fibers in the spinothalamic tract (STT) following stimulation with a CO(2) laser using a new method. We delivered non-painful laser pulses to tiny areas of the skin overlying the vertebral spinous processes at different levels from the 7(th) cervical (C7) to the 12(th) thoracic (T12), and recorded cerebral evoked potentials in 11 healthy men. ⋯ The mean CV of C-fibers in the STT was 2.2+/-0.6 m/s, which was significantly lower than the CV of the Adelta-fibers (10.0+/-4.5 m/s). This technique is novel and simple, and should be useful as a diagnostic tool for assessing the level of spinal cord lesions.
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Neuroscience letters · Sep 2001
Combined epineurial therapy with neutralizing antibodies to tumor necrosis factor-alpha and interleukin-1 receptor has an additive effect in reducing neuropathic pain in mice.
Monotherapy with antibodies to tumor necrosis factor-alpha (TNF) or interleukin-1 receptor 1 (IL-1R1) reduces hyperalgesia in an animal model of painful neuropathy. Here we investigated whether combined therapy with epineurial anti-TNF and anti-IL-1R1 antibodies produces a further advantage. ⋯ There were no detectable differences in IL-1beta and TNF endoneurial protein expression between animals with monotherapy and combined treatment. We conclude that combined anti-cytokine therapy may be a useful strategy in the treatment of neuropathic pain.