Articles: hyperalgesia.
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Randomized Controlled Trial Comparative Study Clinical Trial
Intrathecal, but not intravenous adenosine reduces allodynia in patients with neuropathic pain.
Intrathecal adenosine reduces allodynia from intradermal capsaicin in human volunteers, and reduces hypersensitivity to mechanical stimuli in animals with nerve injury. Although both intrathecal and intravenous adenosine have been reported to relieve pain in patients with neuropathic pain, there are no controlled trials of this therapy. In order to determine the effect of adenosine, seven patients with chronic neuropathic pain and stable areas of mechanical hyperalgesia and allodynia were recruited. ⋯ Intrathecal, but not intravenous adenosine, caused backache in five of seven patients, lasting 6 h. These results indicate that intrathecal adenosine reduces allodynia and pain from stimulation in the area of allodynia, whereas the same dose of adenosine intravenously was ineffective. Given the modest effect and common side effects, the role for intrathecal adenosine as a sole agent for the treatment of neuropathic pain may be limited.
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Psychosomatic medicine · Sep 2003
Clinical Trial Controlled Clinical TrialPlacebo and Nocebo responses, cortisol, and circulating beta-endorphin.
The experiment tested whether the placebo and nocebo responses could be mediated via modulation of stress. ⋯ A placebo response, ie, a reduced pain level, was seen in the Placebo group at 15 minutes after the injection. The placebo response was not related to stress or to beta-endorphin. Expectation of a pain increase in the Nocebo group led to an increase in cortisol, but the expectation of pain increase and the resultant cortisol increase had no effect on pain.
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Irritable bowel syndrome (IBS) is one of the most common gastrointestinal illnesses and is characterized by altered visceral perception. The aim of the study was to determine if local anesthetic blockade of peripheral visceral nociceptive input reduces both visceral and cutaneous secondary hyperalgesia in IBS patients. Ten women with IBS (mean age 30+/-10 years) and ten control subjects (all women) (mean age 29+/-7 years) rated pain intensity and unpleasantness to distension of the rectum (35 mmHg) and thermal stimulation (47 degrees C) of the foot before and after rectal administration of either lidocaine jelly or saline jelly in a double blind crossover design. ⋯ The results of this study support the hypothesis that local anesthetic blockade of peripheral impulse input from the rectum/colon reduces both visceral and cutaneous secondary hyperalgesia in IBS patients. The results provide further evidence that visceral hyperalgesia and secondary cutaneous hyperalgesia in IBS reflects central sensitization mechanisms that are dynamically maintained by tonic impulse input from the rectum/colon. Rectal administration of lidocaine jelly may also be a safe and effective means of reducing pain symptoms in IBS patients.
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Secondary mechanical hyperalgesia has been demonstrated in postoperative patients indicating that central sensitization occurs after surgery. However, the underlying mechanisms are unknown. Here, we studied the role of spinal N-methyl-D-aspartate and alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA)/kainate receptors for pain behaviors indicating secondary hyperalgesia caused by gastrocnemius incision in the rat. ⋯ These results indicate that spinal sensitization contributing to behaviors for secondary hyperalgesia after incision requires Ca(2+) permeable AMPA/kainate receptors. The data further demonstrate that behaviors for secondary mechanical hyperalgesia after incision can be inhibited without affecting behaviors for primary mechanical hyperalgesia and guarding. Mechanisms for central sensitization causing secondary hyperalgesia in postoperative patients may therefore be separated from spontaneous pain and hyperalgesia that arises adjacent to the area of the incision.
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Anesthesia and analgesia · Sep 2003
Clinical TrialIntravenous remifentanil produces withdrawal hyperalgesia in volunteers with capsaicin-induced hyperalgesia.
Opioids administered during surgery may be beneficial by preempting postoperative pain or detrimental by causing acute tolerance. We used a stable model of hyperalgesia in volunteers to test whether acute opioid exposure also results in such pain sensitization over a period of hours in humans. Ten healthy volunteers were studied. ⋯ Areas of hyperalgesia and allodynia continuously enlarged 4 h after remifentanil was stopped, to 180% +/- 47% and 180% +/- 86%, respectively. This study demonstrates that acute opioid exposure enhances hypersensitivity for hours after exposure. If applicable to the surgical setting, this could increase the dose of opioid required for postoperative analgesia and enhance, rather than inhibit, postoperative pain.