Pain
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Randomized Controlled Trial Comparative Study Clinical Trial
Avoidance versus focused attention and the perception of pain: differential effects for men and women.
The aim of the current investigation was to compare the effects of two different attentional strategies (focused vs. avoidance) on how males and females respond to experimentally induced pain. One hundred healthy adults were instructed to either attend towards or away from cold pressor pain. Measures of pain tolerance, pain threshold and recovery were taken, as were self-report measures of sensory and affective pain experiences. ⋯ With respect to the self-report measures, males reported less sensory pain when they attended toward the pain than when they avoided it. However, a similar effect was not found in women, suggesting that attentional focusing may only be a useful strategy for males. These results are discussed in light of previous research.
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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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Randomized Controlled Trial Clinical Trial
Relative potency of epidural to intrathecal clonidine differs between acute thermal pain and capsaicin-induced allodynia.
Clonidine is approved in the US for epidural administration in the treatment of intractable neuropathic cancer pain, but is also administered intrathecally for this indication and both epidurally and intrathecally in the treatment of acute, postoperative pain. The purpose of the current study was to estimate the relative potency of clonidine by epidural and intrathecal routes in the treatment of capsaicin-induced hyperalgesia and allodynia as a model of central hypersensitivity and of noxious heat as a model of acute pain. Twenty-four healthy volunteers were randomized to receive either intrathecal clonidine (75, 150, or 300 micrograms) or epidural clonidine (150, 300, or 600 micrograms) and rated pain from a Peltier-controlled thermode at a lumbar, thoracic, and cervical dermatomal site before and after drug administration. ⋯ For acute thermal pain, intrathecal clonidine produced a dose-dependent analgesia with a lumbar>thoracic>cervical gradient, whereas only one dose of epidural clonidine reduced thermal pain and this was at the thoracic testing site. In contrast, the potency of clonidine to reduce capsaicin-induced allodynia was similar between the two routes of injection, and for hyperalgesia, clonidine was only slightly more potent after intrathecal than epidural injection. These data support clinical studies from non-comparative trials and suggest there is a >6-fold potency ratio of intrathecal:epidural administration of clonidine for acute pain, but a <2-fold potency ratio for these routes for mechanical hypersensitivity.
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Randomized Controlled Trial Comparative Study Clinical Trial
Fear and anxiety: divergent effects on human pain thresholds.
Animal studies suggest that fear inhibits pain whereas anxiety enhances it; however it is unclear whether these effects generalize to humans. The present study examined the effects of experimentally induced fear and anxiety on radiant heat pain thresholds. Sixty male and female human subjects were randomly assigned to 1 of 3 emotion induction conditions: (1) fear, induced by exposure to three brief shocks; (2) anxiety, elicited by the threat of shock; (3) neutral, with no intervention. ⋯ Pain rating data indicated that participants used consistent subjective criteria to indicate pain thresholds. Both subjective and physiological indicators (skin conductance level, heart rate) confirmed that the treatment conditions produced the targeted emotional states. These results support the view that emotional states modulate human pain reactivity.