Pain
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Randomized Controlled Trial Clinical Trial
Blockade of nocebo hyperalgesia by the cholecystokinin antagonist proglumide.
In patients who reported mild postoperative pain, we evoked a nocebo response, a phenomenon equal but opposite to placebo. Patients who gave informed consent to increase their pain for 30 min received a substance known to be non-hyperalgesic (saline solution) and were told that it produced a pain increase. A nocebo effect was observed when saline was administered. ⋯ The blockade of the nocebo hyperalgesic response was not reversed by 10 mg of naloxone. These results suggest that cholecystokinin mediates pain increase in the nocebo response and that proglumide blocks nocebo through mechanisms not involving opioids. Since the nocebo procedure represents an anxiogenic stimulus and previous studies showed a role for cholecystokinin in anxiety, we suggest that nocebo hyperalgesia may be due to a cholecystokinin-dependent increase of anxiety.
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Review
Pain relief from intra-articular morphine after knee surgery: a qualitative systematic review.
Reduction of postoperative pain by injecting opioid into the knee joint is believed to support the hypothesis of peripheral opioid receptor activation in inflammation. The study design consisted of a systematic review of randomised controlled trials (RCTs). Main outcomes were pain intensity and the use of supplementary analgesics. ⋯ We conclude that intra-articular morphine may have some effect in reducing postoperative pain intensity and consumption of analgesics. These studies had significant problems in design, data collection, statistical analysis and reporting. Trials of better methodological quality are needed for a conclusive answer that intra-articular morphine is analgesic, and that any analgesia produced is clinically useful.
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Randomized Controlled Trial Clinical Trial
Characterisation of capsaicin-induced mechanical hyperalgesia as a marker for altered nociceptive processing in patients with rheumatoid arthritis.
Rheumatoid arthritis (RA) is characterised by pain and tenderness not only over inflamed or damaged joints, but also over apparently normal tissues. Experimental models suggest that these features results from changes of sensitivity within both peripheral and central neurones, but direct evidence from human disease is lacking. At present, most clinical studies have evaluated overall pain experience rather than activity within components of the nociceptive pathway. ⋯ Peripheral sensory activity over the forearms of rheumatoid patients has previously been shown to be normal and the results suggest the presence of enhanced central mechanisms in this disorder. The correlation between capsaicin-induced hyperalgesia and joint tenderness in the RA patients implies that joint symptoms arise partially as a result of central, and not exclusively peripheral, factors. The study supports the use of capsaicin-based techniques to explore nociceptive mechanisms in clinical disorders characterised by chronic pain.
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Randomized Controlled Trial Clinical Trial
The Chronic Pain Grade questionnaire: validation and reliability in postal research.
The Chronic Pain Grade questionnaire has been proposed as an interview-administered, multi-dimensional measure of chronic pain severity in selected populations with chronic pain in the United States of America. It has not previously been tested in the United Kingdom, in self-completion form or in an unselected general population. We undertook a postal survey to assess its reliability, validity and acceptability in these circumstances, using a general practice population in Scotland, with a practice population of 11202 patients. ⋯ Construct validity was confirmed by testing scores against duration of pain and treatment sought for pain. We concluded that the Chronic Pain Grade questionnaire is a useful, reliable and valid measure of severity of chronic pain. It translates well into UK English and is acceptable in general population postal research.
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Pain symptoms of many disorders are reported to vary with menstrual stage. This study investigated how pain thresholds to electrical stimulation of the skin, subcutis and muscle tissue varied with menstrual stage in normal women and compared these variations with those in women with dysmenorrhea and in healthy men at matched intervals. Thresholds of the three tissues were measured four times during the course of one menstrual cycle at four sites. ⋯ The amount of abdominal muscle hyperalgesia correlated significantly with the amount of spontaneous menstrual pain. Only minor sex differences were observed for pain thresholds of the arm and leg, but there was a unanimous refusal by men, but not by women, to be tested at abdominal sites. These results indicate that menstrual phase, dysmenorrhea status, segmental site, tissue depth and sex all have unique interacting effects on pain thresholds, thus adding more items to the lengthy and still-growing list of biological factors that enter into an individual's judgment of whether or not a stimulus is painful.