Articles: analgesia.
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Spinal cord stimulator insertion can sometimes be impossible to achieve because of pain during attempted electrode advancement. Heavy sedation and general anaesthesia are contraindicated and epidural analgesia would appear to be a logical, but overlooked solution. A case is described where dilute lignocaine abolished prohibitive pain but left the appreciation of stimulation paraesthesias unaffected. The advantages of such an approach are discussed.
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J. Pharmacol. Exp. Ther. · May 1996
Electrical stimulation at traditional acupuncture sites in periphery produces brain opioid-receptor-mediated antinociception in rats.
Previous studies in rats measuring latency to tail flick with radiant heat have shown that the antinociceptive effect induced by electrical stimulation of different frequencies at traditional acupuncture sites is mediated via different opioid receptors in the spinal cord. The present study was designed to observe (1) whether electrical stimulation at such sites could produce antinociceptive effects in the cold water tail-flick (CWT) test; (2) whether the antinociceptive effects could be blocked by s.c. injection of the opioid receptor antagonist naloxone and (3) whether i.c.v. injection of selective antagonists for mu (cyclic D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2, CTAP), delta (naltrindole) or kappa (nor-binaltorphimine) opioid receptors would block the antinociceptive effect produced by electrical stimulation. Sprague-Dawley rats were stimulated at frequencies of 2, 30 or 100 Hz with acupuncture needles inserted into acupoints Zusanli and Sanyinjiao in the hind leg for 30 min. ⋯ The results showed that (1) a significant, frequency-related increase in threshold in the CWT was observed in all electrical stimulation groups as compared with the placebo group and the antinociceptive effect lasted about 30 min poststimulation; (2) naloxone (s.c.) antagonized the antinociceptive effect induced by 2 Hz, 30 Hz or 100 Hz electrical stimulation and (3) either CTAP or naltrindole (i.c.v.) almost completely blocked the antinociceptive effect induced by 2 Hz or 30 Hz electrical stimulation, but was less effective in blocking antinociception induced by 100 Hz electrical stimulation; nor-binaltorphimine (i.c.v.) greatly reduced antinociception induced by 30 Hz or 100 Hz electrical stimulation, but not by 2 Hz electrical stimulation. These results indicate that the antinociception induced by 2 Hz electrical stimulation is mediated by both mu and delta opioid receptors; the antinociception induced by 100 Hz electrical stimulation is mediated primarily by the kappa receptor; and the antinociception induced by 30 Hz electrical stimulation is mediated by all three opioid receptor types. Thus, the antinociceptive effect induced by peripheral electrical stimulation, as measured by the CWT, involves opioid receptors in the rat brain.
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Recent evidence has suggested that the timing of administration of analgesic drugs could influence their efficacy by reducing the sensitization of the nervous system induced by the nociceptive inputs, but this concept of preemptive analgesia is still debated in both clinical and basic research. ⋯ These results show that a slight advantage of infiltration with bupivacaine before injury exists in this carrageenin model of acute inflammatory pain. However, this benefit is limited in time and bupivacaine did not have any preemptive analgesic effect.
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Epidural analgesia and anesthesia are standard regional techniques in orthopaedic surgery of the lower extremities. Benefits of epidural anesthetic infusions include excellent analgesia, minimal respiratory depression, no somnolence, and decreased need for blood transfusion. Adverse effects include pruritus, nausea, and urinary retention, but standard methods have evolved to counter each adverse effect. ⋯ Sixty-four patients experienced satisfactory analgesia with minimal adverse effects. The technique worked despite multiple laminotomies for segmental fixation and did not compromise neurologic assessment. We conclude that epidural analgesia is as safe and effective after spinal-deformity surgery as it is after other types of surgery.