The journal of pain : official journal of the American Pain Society
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Clinical Trial
Altering gender role expectations: effects on pain tolerance, pain threshold, and pain ratings.
The literature demonstrating sex differences in pain is sizable. Most explanations for these differences have focused on biologic mechanisms, and only a few studies have examined social learning. The purpose of this study was to examine the contribution of gender-role stereotypes to sex differences in pain. ⋯ Women had briefer tolerance times and higher post-cold pressor ratings than men. When given gender-specific tolerance expectations, men and women did not differ in their pain tolerance, pain threshold, or pain ratings. This is the first empirical study to show that manipulation of expectations alters sex differences in laboratory pain.
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Case Reports
Severe intraoperative hypertension and opioid-resistant postoperative pain in a methadone-treated patient.
Patients who are treated with methadone present challenges for the anesthesiologist. We report the untoward effects of rapid preoperative methadone tapering on the operative and perioperative course of a patient who required emergency surgery. The patient's exaggerated stress response to surgery and severe intractable postoperative pain might have resulted from unrecognized methadone withdrawal. Continuation of methadone treatment in patients who have surgery may prevent exaggerated intraoperative hemodynamic responses to surgical stimuli and unnecessary postoperative suffering.
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This study measured mechanical sensation and pain thresholds in the cutaneous field overlying the knee joints of rheumatoid arthritis (RA; N = 27) and osteoarthritis (OA; N = 28) patients, compared with age- and weight-matched normal control subjects (Norm; N = 27) by using graded von Frey monofilaments. A visual analog scale (VASpain), cutaneous joint temperature and circumference were measured for subjective ongoing pain and inflammation. ⋯ The highest scores in average mechanical sensation mapped to the same grid region as the lowest scores in average pain thresholds in RA and OA patients. The simultaneous hypoesthesia and allodynia, with paradoxical decrease in sensation and increased pain thresholds may reflect peripheral and central alterations in neuronal responsiveness to mechanical stimulation and suggests activation of a descending inhibitory system.
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Inflammation of a peripheral nerve (neuritis) causes mechanical and thermal hyperalgesia in the region in which the inflamed nerve innervates. We investigated whether peripherally applied norepinephrine (NE) would exacerbate mechanical hyperalgesia in rats with neuritis. After inflammation of the left L5 spinal nerve with complete Freund's adjuvant, the foot withdrawal thresholds to mechanical stimuli applied to the affected hind paw (mechanical thresholds) were decreased significantly, indicating the development of mechanical hyperalgesia. ⋯ The effect of NE on mechanical hyperalgesia was mediated by both peripheral alpha(1)- and alpha(2)-adrenoceptors. Immunohistochemical study of the previously inflamed nerve showed that proinflammatory cytokine tumor necrosis factor immunoreactivity was significantly higher in the rats showing adrenergic sensitivity compared to rats without adrenergic sensitivity. The data thus suggest that peripheral NE, when released in an excessive amount from the sympathetic nervous system, might play an important role in the aggravation of pain in neuritis.
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Pulsed radiofrequency, in which short bursts of radiofrequency energy are applied to nervous tissue, has been recently described as an alternative technique devoid of nerve injury, a subsequent side effect of thermal lesions created by continuous radiofrequency lesioning. Yet the mechanism of this effect remains unclear. In this study we compared the acute effects of pulsed versus continuous radiofrequency energy on impulse propagation and synaptic transmission in hippocampal slice cultures and on cell survival in cortical cultures. ⋯ In addition, although both continuous radiofrequency and pulsed radiofrequency treatments induced a distance-dependent tissue destruction under the stimulating needle, the effect was more pronounced in the continuous radiofrequency group. These findings suggest that the acute effects of pulsed radiofrequency are more reversible and less destructive in nature than the classic continuous radiofrequency mode, even in normothermal conditions. This model might help elucidate the importance of various parameters for the clinical application of radiofrequency lesioning and might open new horizons for the role of pulsed radiofrequency lesioning in cases of neuropathic pain.