Pain
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This is the first neural imaging study to use regional cerebral blood flow (rCBF) in an animal model to identify the patterns of forebrain nociceptive processing that occur during the early and late phase of the formalin test. We measured normalized rCBF increases by an autoradiographic method using the radiotracer [99mTc]exametazime. Noxious formalin consistently produced detectable, well-localized and typically bilateral increases in rCBF within multiple forebrain structures, as well as the interpeduncular nucleus (Activation Index, AI = 66) and the midbrain periaqueductal gray (AI = 20). ⋯ The hindlimb region of somatosensory cortex was significantly activated (AI = 31), and blood flow increases in VPL (AI = 8.7) and the medial thalamus (AI = 9.0) exhibited a tendency to be greater in the late phase as compared to the early phase of the formalin test. The spatial pattern and intensity of activation varied as a function of the time following the noxious formalin stimulus. The results highlight the important role of the limbic forebrain in the neural mechanisms of prolonged persistent pain and provide evidence for a forebrain network for pain.
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The compatibility of ketamine and morphine mixture was studied. In addition, pH adjustment to minimise local tissue irritation led to no change in stability of the mixture up to pH 5.9. It appears that ketamine and morphine mixtures are stable over a 24 h period.
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Randomized Controlled Trial Clinical Trial
The NMDA receptor antagonist amantadine reduces surgical neuropathic pain in cancer patients: a double blind, randomized, placebo controlled trial.
Neuropathic pain is often severe, persistent, and responds poorly to analgesic medications. Recent evidence suggests that N-methyl-D-aspartate (NMDA) receptor antagonists may be effective in the treatment of neuropathic pain. The present trial was designed to test the efficacy of acute administration of the NMDA receptor antagonist amantadine in relieving surgical neuropathic pain in patients with cancer. ⋯ Amantadine, but not the placebo, also reduced 'wind up' like pain (caused by repeated pinpricking) in four patients. We conclude that amantadine infusion is a safe and effective acute treatment for surgical neuropathic pain in cancer patients. Further trials with long-term oral or parenteral amantadine treatment should be conducted.
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Randomized Controlled Trial Clinical Trial
Patient-controlled versus staff-controlled analgesia with pethidine after allogeneic bone marrow transplantation.
Patients treated by allogeneic bone marrow transplantation (aBMT) suffer prolonged oropharyngeal mucositis pain. The aim of this study was to prospectively compare patient-controlled analgesia (PCA) with an established regimen of staff-controlled analgesia using pethidine (meperidine). Twenty patients undergoing aBMT for haematologic neoplasias or malignant lymphomas randomly received pethidine intravenously either continuously plus supplemental bolus doses on request through the transplant unit staff or by PCA. ⋯ This observation is discussed as a possible Hawthorne effect. Previous studies using morphine demonstrated that PCA diminishes opioid requirement compared to continuous or staff-controlled application in bone marrow recipients. In contrast to these studies, PCA additionally improved pain relief in the present investigation.
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A prospective observational study of cohorts of patients undergoing hip replacement (30), knee replacement (31), and spinal nerve root decompressive surgery (30) were interviewed pre-operatively to identify factors which might correlate with and potentially predict severe post-operative pain and dissatisfaction with analgesic management. The hip patients comprised 33% females and averaged 64 years, while the knee patients were 45% female and older (mean 71 years) and the spinal patients were 43% female and averaged 50 years. The three groups were similar with respect to all other pre-operative variables. ⋯ Significant (P < or = 0.01) multivariate correlates of severe post-operative pain assessed by logistic regression analysis of 11 variables were female gender, high pre-operative pain severity, and younger age. Significant (P < or = 0.01) multivariate correlates of both worse than expected pain experience and low satisfaction were female gender, high pre-operative pain severity, high anxiety about risks and problems, low expected pain severity, age (younger) and high willingness to report pain. These variables may reasonably be tested in further studies as potential predictors of adverse post-operative pain experience.