Pain
-
Pain is the major complaint of the estimated one million U. S. consumers who use acupuncture each year. Although acupuncture is widely available in chronic pain clinics, the effectiveness of acupuncture for chronic pain remains in question. ⋯ Six or more acupuncture treatments were significantly associated with positive outcomes (P=0.03) even after adjusting for study quality. We conclude there is limited evidence that acupuncture is more effective than no treatment for chronic pain; and inconclusive evidence that acupuncture is more effective than placebo, sham acupuncture or standard care. However, we have found an important relationship between the methodology of the studies and their results that should guide future research.
-
Although intrathecal administration of baclofen, a selective GABA(B)-receptor agonist, is known to have an antinociceptive effect on various pain models, the role of presynaptic GABA(B) receptors in antinociception is not well characterized. In the present study, the action of baclofen on primary afferent-evoked glutamatergic excitatory transmission was examined in substantia gelatinosa (SG) neurons of an adult rat spinal cord slice with an attached dorsal root, prepared from the lumbar segment, by use of the blind whole-cell patch-clamp technique. Under the condition where a postsynaptic action of baclofen was inhibited, baclofen (1 microM) reduced the amplitudes of excitatory postsynaptic currents (EPSCs; V(H)=-70 mV) which were monosynaptically evoked by stimulating primary-afferent C- and/or Adelta-fibers and which were remarkably depressed by CNQX (10 microM). ⋯ Baclofen (1 microM) did not affect a response of SG neurons to bath-applied AMPA (10 microM). These results indicate that baclofen inhibits the release of L-glutamate from Adelta and C primary-afferent terminals in the SG through the activation of GABA(B) receptor; this action is more effective to C-fiber than Adelta-fiber transmission. Considering that the SG is the main part of termination of Adelta- and C-fibers transmitting nociceptive information, the present finding would account for at least a part of the inhibitory action of baclofen on pain transmission.
-
This study tested the hypothesis that fibromyalgia patients display hypervigilance for somatosensory signals. Hypervigilance was operationalized as the detection of weak electrocutaneous stimuli. Innocuous electrical stimuli gradually increasing in strength were administered to one of four different body locations. ⋯ No evidence for hypervigilance for innocuous signals was found: patients did not show superior detection of electrical stimuli either under single or dual task conditions. Also, no differences were found between patients and controls on the body vigilance questionnaire. Detection of electrical stimuli was, however, predicted by pain-related fear and pain vigilance.
-
Randomized Controlled Trial Clinical Trial
Preinjury treatment with morphine or ketamine inhibits the development of experimentally induced secondary hyperalgesia in man.
We examine the effect of morphine or ketamine (N-methyl-D-aspartate receptor antagonist; NMDA) treatment on secondary hyperalgesia. Drug treatment started preinjury and continued into the early postinjury period. Hyperalgesia was induced by a local 1 degrees burn injury covering 12.5 cm(2) on the medial side of the calf. ⋯ In a previous study, we found that postinjury treatment alone with morphine did not affect secondary hyperalgesia, whereas ketamine did so significantly. The differential response to morphine administered pre- or postinjury may be relevant to the recently shown NMDA receptor mediated interaction of central hyperexcitability and morphine antinociception. The effect of ketamine supports the hypothesis of the role of NMDA receptor mediation in central hyperexcitability.
-
Randomized Controlled Trial Clinical Trial
Assessment of the effect of EMLA during venipuncture in the newborn by analysis of heart rate variability.
The objective of this study was to investigate the effect of EMLA on the pain response when venipuncture was performed in 60 3-day-old healthy newborns. EMLA/placebo was applied to the back of the baby's hand, following a randomized, double-blind procedure. ECG and crying were recorded during the test. ⋯ The occurrence of crying during venipuncture did not differ significantly between the EMLA and the placebo groups. The placebo-treated group showed a statistically significant higher HR, and a decrease in variance (total power) and power in the low-frequency band (0.02-0.15 Hz) when compared with the EMLA group. We conclude that EMLA decreases the stress response during venipuncture in newborn infants.