Pain
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Occlusal treatments (occlusal splints and occlusal adjustment) are controversial but widely used treatment methods for temporomandibular disorders (TMD). To investigate whether studies are in agreement with current clinical practices, a systematic review of randomized controlled trials (RCTs) of occlusal treatment studies from the period 1966 to March 1999 was undertaken. Eighteen studies met the inclusion criteria, 14 on splint therapy, and 4 on occlusal adjustment. ⋯ The use of occlusal splints may be of some benefit in the treatment of TMD. Evidence for the use of occlusal adjustment is lacking. There is an obvious need for well designed controlled studies to analyse the current clinical practices.
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A number of studies have examined the effects of naloxone on nitrous oxide-induced analgesia with conflicting results. In the present study the effects of a relatively high dose of naloxone was examined to determine its effects on nitrous oxide-induced analgesia, as well as on the subjective and psychomotor effects of nitrous oxide. Fourteen subjects participated in a four-session crossover trial in which they received intravenous injections of either saline or 30mg/70kg naloxone 10min into a 35min period in which they were inhaling either 100% oxygen or 30% nitrous oxide in oxygen. ⋯ Subjects reported higher pain ratings after the naloxone injection than the saline injection, but there was no evidence of naloxone reversing the analgesic effects of nitrous oxide. Similarly while naloxone also affected mood and impaired psychomotor performance, there was no evidence of naloxone reversing the effect of nitrous oxide on these measures. The results of this study call into question the role of the opioidergic system in mediating various effects of nitrous oxide in humans.
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Randomized Controlled Trial Clinical Trial
Suckling- and sucrose-induced analgesia in human newborns.
This experiment had three goals: 1. To identify the basis of sucking-induced analgesia in healthy, term, newborn humans undergoing the painful, routine, procedure of heel lance and blood collection. 2. To evaluate how taste-induced and sucking-induced analgesias combine to combat pain. 3. ⋯ Sucking an unflavored pacifier was analgesic when and only when suck rate exceeded 30 sucks/min. 2. The combination of sucrose and nonnutritive sucking was remarkably analgesic; we saw no behavioral indication in nine of the ten infants that the heel lance had even occurred. 3. Grimacing was reduced to almost naught by procedures that essentially eliminated crying and markedly reduced heart rate during the blood harvesting procedure.
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Previous studies have shown that transection of the sciatic nerve induces dramatic changes in sodium currents of axotomized dorsal root ganglion (DRG) neurons, which are paralleled by significant changes in the levels of transcripts of several sodium channels expressed in these neurons. Sodium currents that are resistant to tetrodotoxin (TTX-R) and the transcripts of two TTX-R sodium channels are significantly attenuated, while a rapidly repriming tetrodotoxin-sensitive (TTX-S) current emerges and the transcripts of alpha-III sodium channel, which produce a TTX-S current when expressed in oocytes, are up-regulated. ⋯ Transcripts of NaN and SNS, two sensory neuron-specific TTX-R sodium channels, are significantly down-regulated as is the TTX-R sodium current, while transcripts of the TTX-S alpha-III sodium channel and a rapidly repriming TTX-S Na current are up-regulated in small diameter DRG neurons. These changes may provide at least a partial basis for the hyperexcitablity of DRG neurons that contributes to hyperalgesia in this model.
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In this preliminary study, we evaluated the effects of methylnaltrexone, a peripheral opioid-receptor antagonist, on chronic opioid-induced gut motility and transit changes in four subjects with chronic methadone-induced constipation. Subjects participated in this single blind, placebo controlled study for up to 8 days. We gave placebo the first day; for the remainder of the study, we gave intravenous methylnaltrexone (0.05-0.45 mg/kg) twice daily. ⋯ Oral-cecal transit times of Subjects 1, 3, and 4 were reduced from 150, 150 and 150 min (after placebo) to 90, 60 and 60 min (with methylnaltrexone), respectively. Our preliminary results demonstrate that low dose intravenous methylnaltrexone effectively reversed chronic methadone-induced constipation and delay in gut transit time. Thus, we anticipate that cancer patients receiving chronic opioids may also have increased sensitivity to methylnaltrexone, and that low dose methylnaltrexone may have clinical utility in managing opioid-induced constipation in chronic-pain patients.