Pain
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Randomized Controlled Trial Clinical Trial
Effects of intravenous ketamine, alfentanil, or placebo on pain, pinprick hyperalgesia, and allodynia produced by intradermal capsaicin in human subjects.
The importance of N-methyl-D-aspartate (NMDA) receptor-mediated sensitization of central nervous system (CNS) neurons is well established in animal models of acute and chronic pain. A human model of central sensitization would be useful in screening new NMDA antagonists and establishing dose regimens for clinical trials in patients with pain related to sensitization of CNS neurons. We used this model to examine the effects of intravenous infusions of two centrally acting analgesics, the NMDA receptor antagonist ketamine and the morphine-like opioid agonist alfentanil. ⋯ Because the drugs were given systemically and produced side effects in all subjects, we cannot specify the site or sites of action nor conclusively rule out a non-specific 'active placebo' response as the cause for reduction of symptoms. Arguing against an 'active placebo' response, however, was the lack of analgesic effect of intravenous midazolam (mean dose; 3.4 mg, titrated to produce side effects of similar magnitude to ketamine and alfentanil) given at 145 min after capsaicin in 9 subjects who had received saline from 25 to 60 min. The results of this study suggest that neural systems sensitive to NMDA receptor antagonists and opioids participate in capsaicin-evoked pain phenomena, and support the feasibility of pharmacological studies using the intradermal capsaicin model.
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Substantial research has demonstrated that cognitive psychological techniques including distraction can increase pain tolerance. In recent years, there also have been claims that humor and laughter possess unique characteristics for coping with pain and stress. Theoretically, explanations include the release of endorphins, the lowering of tension, as well as the distraction that results from humor. ⋯ The repulsive group yielded the largest increase in pain tolerance although not different from the humor group. Except for sex differences, pain ratings did not show any group effects. Discussion focused on the type of distraction that would be meaningful for increasing pain tolerance and on the place of humor in pain control.
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We have reviewed 293 papers published since 1950 to assess the evidence of effect of ultrasound in the treatment of musculoskeletal disorders. Twenty-two clinical papers describing trials comparing ultrasound treatment with sham-ultrasound treated, non-ultrasound treatment and untreated groups were found. These papers were evaluated with respect to a list of criteria which should be met in this type of trial. ⋯ An analysis of the effect of proper randomisation on the result was not possible because of inadequate description of the methods used. We conclude that the use of ultrasound in treatment of musculoskeletal disorders is based on empirical experience, but is lacking firm evidence from well-designed controlled studies. One question remaining is whether ultrasound treatment can augment an effect of exercise therapy with respect to musculoskeletal disorders.
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The oxygen-15 water bolus positron emission tomography (PET) method was used to image regional brain activity in 4 patients with chronic post-traumatic neuropathic pain confined to one lower limb and in 1 patient with post-herpetic neuralgia. In comparison to 13 normal subjects, scans of the patients disclosed a statistically significant decrease in thalamic activity contralateral to the symptomatic side. Examination of the right/left ratio for all the subjects showed that the values for the patients fell at the extremes of the normal range, according to the side of the affected body part. These initial observations suggest that functional alterations in thalamic pain processing circuits may be an important component of chronic neuropathic pain.
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This paper reports on the experience gained using World Health Organization Guidelines for cancer pain relief over a 10-year period in an anaesthesiology-based pain service associated with a palliative care programme. The course of treatment of 2118 patients was assessed prospectively over a period of 140,478 treatment days. Non-opioid analgesics (WHO step I) were used on 11%, weak opioids (WHO step II) on 31% and strong opioids (WHO step III) on 49% of treatment days. ⋯ During the course of treatment, the latter were the major symptoms on 23% of days, followed by nausea (23%), constipation (23%) and anorexia (20%). Our results emphasise once again the marked efficacy and low rate of complications associated with oral and parenteral analgesic therapy as the mainstay of pain treatment in the palliative care of patients with advanced cancer. Wide dissemination of WHO guidelines among doctors and healthcare workers is thus necessary to effect a clear improvement in the treatment of the many patients suffering from cancer pain in the clinical and home setting.