Pain
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Comparative Study
Effect of ketamine, an NMDA receptor inhibitor, in acute and chronic orofacial pain.
We examined the analgesic effect of racemic ketamine and its 2 enantiomers in 16 female patients (age: 20-29 years) suffering acute pain after oral surgery and in 7 female patients (age: 42-79 years) suffering chronic neuropathic orofacial pain. All 3 forms of ketamine consistently relieved postoperative pain, (S)-ketamine being 4 times more potent than (R)-ketamine. The analgesic effect was maximal 5 min after i.m. injection and lasted for about 30 min. ⋯ Relative to the analgesic effect (S)-ketamine caused more disturbing side effects than did (R)-ketamine. The mean serum concentration of each form of ketamine at the time of maximal effect was close to the approximate Kd value for PCP site occupancy by that particular form. This is in concert with the hypothesis that the effect of ketamine on acute nociceptive pain is due to N-methyl-D-aspartate (NMDA) receptor inhibition and adds to the evidence that NMDA receptors are important for the perception of acute, nociceptive pain in humans.(ABSTRACT TRUNCATED AT 250 WORDS)
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Improved methods for pain measurement have both theoretical and clinical importance. This study evaluated the Descriptor Differential Scale (DDS) of Pain Intensity, a recent methodology designed for assessing pain reports in clinical samples. Experiment 1 evaluated the sensitivity of the measure to small changes in electrocutaneous stimulation relative to a traditional visual analogue scale (VAS) of pain intensity. ⋯ Experiment 2 evaluated the performance of the measure in both experimental and clinical pain samples, as well as the similarity of item-response patterns in each of these samples. Results indicate that the DDS of Pain Intensity is sensitive to small changes in electrocutaneous stimulation, has consistent ratio-scale properties across two different psychophysical methods, and demonstrates similar item-response patterns across divergent experimental and clinical samples. The results support the validity of the sensory DDS as a measure of pain intensity.
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Spinal cord stimulation (SCS) is efficacious for pain due to injury of peripheral nerves, and therefore models of mononeuropathy appear to be particularly suitable for an experimental approach to the study of mechanisms underlying the clinical effect of this mode of treatment in chronic neuropathic pain. Virtually all previous experimental studies on SCS have utilized acute and nociceptive types of peripheral pain stimuli to explore the attenuating effects of SCS. In the present study we made use of the two models of supposedly painful neuropathy developed by Bennett and Xie (1988) and Seltzer et al. (1990) to explore the effect of SCS applied with stimulus parameters similar to those used in clinical practice. ⋯ The late, C fibre-mediated component was not influenced by SCS. The first component of the flexor reflex is conceivably mediated by A beta-fibre activation and it presumably corresponds to the withdrawal response induced by innocuous mechanical stimuli. The lack of effect of SCS on the late reflex component indicates that it selectively influences transmission of A-fibre activity. (ABSTRACT TRUNCATED AT 400 WORDS)
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Prolonged and severe diarrhoea after alcohol celiac plexus block is a rare, but life-threatening, complication if not recognized. This type of diarrhoea may be considered an autonomic neuropathy due to sympathetic denervation. ⋯ This drug was maintained at the same dosage and was well tolerated for 4 months until death. Octreotide, an analogue of somatostatin, reduces diarrhoea by suppression of intestinal motility and secretion and offers a useful option in the treatment of this complication of celiac plexus block.
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The patient with a history of current opioid consumption presenting in the acute postoperative setting presents a challenge for pain management. Standard treatment dosages and strategies are often ineffective in providing pain relief. This retrospective case-control study reviews 4 years' experience of the Acute Pain Service (APS) at our institution providing care for 202 chronic pain and opioid-consuming (CPOC) patients, 6.6% of 3058 patients undergoing urologic, gynecologic, orthopedic and general surgical procedures. ⋯ EOA and B/F case studies showed similar results. Moderate sedation was experienced by 50% of CPOC patients receiving PCA. Differences in opioid usage, side effects, pain scores, sedation and prescribed treatment with anxiolytics were shown between CPOC patients and matched controls.(ABSTRACT TRUNCATED AT 250 WORDS)