Pain
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Exposure to sauna heat during sauna bathing raises the skin temperature of the bather near the hot pain perception threshold and enhances sympathetic activity. Self-reports provided by regular bathers of changes in intensity of their ongoing pain might, therefore, add novel information on the effect of intense heat on various pain conditions. We interviewed consecutive patients attending our pain clinic over a period of 1 year about their pain-related responses to sauna bathing and controlled the results by quantitated somatosensory tests. ⋯ By contrast, mechanical allodynia was present in 48% of patients with peripheral neuropathic pain and in 54% of patients with central pain. The results speak against an important role for C-afferent or sympathetic postganglionic fibres in most subclasses of neuropathic pain. Animal models of neuropathic pain should be critically viewed against this finding.
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The local anesthetic lidocaine was injected into the dentate gyrus (DG) of alert, unrestrained rats 10 min prior to investigation within the formalin test. Regional anesthesia of the DG resulted in a reduction of pain scores when administered contralateral to the site of subcutaneous formalin injection. The analgesic effect was evident 30-50 min after central infusion. These results provide evidence of the involvement of the hippocampal formation (HF) in pain perception.