Pain
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Randomized Controlled Trial Clinical Trial
Effect of propranolol and granisetron on experimentally induced pain and allodynia/hyperalgesia by intramuscular injection of serotonin into the human masseter muscle.
We have previously reported that intramuscular injection of serotonin (5-HT) into the masseter muscle elicits pain and allodynia/hyperalgesia in healthy subjects. The aim of this study was to investigate whether the 5-HT(3) receptor antagonist granisetron or 5-HT(1A) receptor antagonist propranolol can reduce 5-HT induced pain and allodynia/hyperalgesia in the masseter muscle. Twenty-four healthy individuals (12 males and 12 females) without pain from the masseter muscle region participated. ⋯ The difference between 5-HT and granisetron+5-HT was significant. In conclusion, the results of this study indicate that injection of granisetron and propranolol into the human masseter muscle reduces pain induced by local administration of 5-HT, but that the effect of granisetron is stronger than that of propranolol. In addition, granisetron totally abolishes allodynia/hyperalgesia.
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Randomized Controlled Trial Clinical Trial
Involvement of presurgical pain in preemptive analgesia for orthopedic surgery: a randomized double blind study.
Preemptive analgesia (PA) is effective in animal models but its clinical effectiveness remains controversial. We examined the effect of preexisting pain on PA. Subjects were recruited from patients needing orthopedic surgery. ⋯ PA was effective when presurgical pain was absent, but ineffective when presurgical pain was present. We propose that central sensitization is already established by presurgical pain, and preserved until the termination of surgery. The ineffectiveness of PA did not depend on whether the pain was acute (fracture surgery) or chronic (arthritic surgery).
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Clinical Trial
Motor cortex stimulation for chronic neuropathic pain: a preliminary study of 10 cases.
There is growing evidence to support the use of motor cortex stimulation (MCS) in the management of patients with chronic neuropathic pain. A prospective audit of ten patients using a modified staged technique for motor cortex implantation provides further evidence for the analgesic effectiveness of this technique. ⋯ We conclude that motor cortex stimulation is an effective analgesic intervention in some patients with chronic neuropathic pain, but it is difficult if not impossible to predict those patients who may respond to treatment prior to implantation. Randomised controlled trials are now urgently needed to test the effectiveness of motor cortex stimulation under double-blind conditions.
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Several lines of evidence suggest that secondary hyperalgesia to punctate mechanical stimuli arises from central sensitization to the input from primary afferent nociceptors. Conventional C-fiber nociceptors respond to heat stimuli and yet heat hyperalgesia is absent in the region of secondary hyperalgesia. This evidence suggests that the central sensitization to nociceptor input does not involve heat sensitive nociceptors. ⋯ However, touch threshold and pain to pinching stimuli were not significantly altered. The intradermal capsaicin injection led to the development of a similar degree of secondary hyperalgesia at both the vehicle and capsaicin treatment areas. These results indicate that capsaicin insensitive nociceptive afferents play a dominant role not only in normal mechanical pain but also in secondary hyperalgesia to noxious mechanical stimuli.
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Irritable bowel syndrome (IBS) and fibromyalgia (FM) are considered chronic syndromes of altered visceral and somatic perception, respectively. Because there is a significant overlap of IBS and FM, shared pathophysiological mechanisms have been suggested. Although visceral perception has been well studied in IBS, somatic perception has not. ⋯ Both hypervigilance and somatic hypoalgesia contribute to the altered somatic perception in IBS patients. Co-morbidity with FM results in somatic hyperalgesia in IBS patients.