Pain
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Comparative Study
Focused analgesia in waking and hypnosis: effects on pain, memory, and somatosensory event-related potentials.
Somatosensory event-related potentials (SERPs) to painful electric standard stimuli under an odd-ball paradigm were analyzed in 12 high hypnotizable (HH), 12 medium hypnotizable (MH), and 12 low hypnotizable (LH) subjects during waking, hypnosis, and a cued eyes-open posthypnotic condition. In each of these conditions subjects were suggested to produce an obstructive imagery of stimulus perception as a treatment for pain reduction. A No-Analgesia treatment served as a control in waking and hypnosis conditions. ⋯ No significant SERP differences were observed for these subjects between treatments in waking condition and between hypnotic and posthypnotic analgesic treatments. For the MH and LH subjects no significant N140 and P200 amplitude changes were observed among analgesic conditions as compared to control conditions. These amplitude findings are seen as indicating that hypnotic analgesia can affect earlier and later stages of stimulus processing.
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We assessed whether intrathecal administration of the uncompetitive and competitive NMDA receptor antagonists ketamine and (+/-)CPP, respectively, could produce differential modulation on chemical and mechanical nociception in normal and monoarthritic rats. In addition, the antinociceptive interaction of ketamine and (+/-)CPP on monoarthritic pain was also studied using isobolographic analysis. Monoarthritis was produced by intra-articular injection of complete Freund's adjuvant into the tibio-tarsal joint. ⋯ Irrespective of the nociceptive test employed, both antagonists showed greater antinociceptive activity in monoarthritic than in healthy rats. Combinations produced synergy of a supra-additive nature in the capsaicin test, but only additive antinociception in paw pressure testing. The efficacy of the drugs, alone or combined, is likely to depend on the differential sensitivity of tonic versus phasic pain and/or chemical versus mechanical pain to NMDA antagonists.