Articles: hyperalgesia.
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Randomized Controlled Trial Multicenter Study Clinical Trial
Systemic adenosine infusion reduces the area of tactile allodynia in neuropathic pain following peripheral nerve injury: a multi-centre, placebo-controlled study.
Systemic adenosine has been shown in earlier case reports and a small placebo-controlled study to reduce pathological sensory dysfunction such as tactile allodynia in neuropathic pain. To evaluate this further, the effects of systemic adenosine infusion (50 microg/kg/min for 60 min) on tactile sensory dysfunction and pain was evaluated in 26 patients suffering peripheral neuropathic pain characterized by dynamic tactile allodynia. A randomized, cross-over, double-blind, placebo-controlled technique was used in this multi-centre study. ⋯ The area of dynamic tactile allodynia was significantly reduced by adenosine compared with placebo (p=0.043), but spontaneous pain and tactile pain threshold were not significantly improved compared with the effects of placebo treatment. As a secondary outcome, a higher incidence of positive subjective effects on the clinical pain condition, in a few cases with long duration (several months), following adenosine treatment was found when the global effect of respective treatment was assessed (p=0.028). The results demonstrate involvement of adenosine receptor-sensitive pain mechanisms in some aspects of the sensory dysfunction often found in neuropathic pain.
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Randomized Controlled Trial Clinical Trial
Effect of pre- or post-traumatically applied i.v. lidocaine on primary and secondary hyperalgesia after experimental heat trauma in humans.
Hyperalgesia on intradermal capsaicin application can be attenuated by systemic application of local anesthetics. We tested whether low doses of local anesthetics applied pre- or post-traumatically can reduce heat trauma-induced primary and secondary hyperalgesia in humans. Six healthy volunteers consented to the randomized, double-blind, and cross-over designed study. ⋯ Thus, local anesthetics at concentrations that do not block nerve conduction substantially affect ongoing central changes in pain processing that are induced by a real tissue trauma. A significant preemptive effect could not be demonstrated. The anti-hyperalgesic effect of lidocaine is likely based on action of central (spinal) sites, but peripheral sites may also be addressed.
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Randomized Controlled Trial Comparative Study Clinical Trial
Peripheral lidocaine but not ketamine inhibits capsaicin-induced hyperalgesia in humans.
We examined the effect of the subcutaneous infiltration of ketamine, lidocaine and saline before injury on capsaicin-induced pain and hyperalgesia. Twelve healthy volunteers participated in two separate, randomized, double-blind, placebo-controlled crossover experiments. In experiment 1, 100 micrograms capsaicin was injected intradermally in one volar forearm 10 min after the skin had been pretreated with lidocaine 20.0 mg in 2.0 ml or 0.9% saline 2.0 ml at the capsaicin injection site. ⋯ Pain scores and areas of hyperalgesia were not affected when the contralateral site was infiltrated with ketamine or lidocaine. Lidocaine produced no side-effects, whereas ketamine produced paraesthesia, dizziness and sleepiness in six out of 24 (25%) cases. Blocking peripheral sodium channels with locally administered lidocaine reduces spontaneous pain and capsaicin-induced hyperalgesia but local block with the NMDA-type glutamate receptor antagonist ketamine has no effect on capsaicin-induced pain and hyperalgesia.
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Anesthesia and analgesia · Oct 2000
Randomized Controlled Trial Clinical TrialThe effect of systemic lidocaine on pain and secondary hyperalgesia associated with the heat/capsaicin sensitization model in healthy volunteers.
Although effective in neuropathic pain, the efficacy of systemic lidocaine in non-neuropathic pain remains uncertain. We investigated the analgesic effect of systemic lidocaine on the heat/capsaicin sensitization model of experimental pain in 24 volunteers. Sensitization was produced by heating the skin to 45 degrees C for 5 min, followed by a 30-min application of 0.075% capsaicin cream, and maintained by periodically reheating the sensitized skin. Subjects received IV lidocaine (bolus 2 mg/kg, then infusion 3 mg. kg. h), or saline for 85 min. Areas of secondary hyperalgesia, heat pain detection thresholds, and painfulness of stimulation with 45 degrees C for 1 min (long thermal stimulation) were quantified. Systemic lidocaine reduced the area of secondary hyperalgesia to brush, but not to von Frey hair stimulation. Lidocaine did not alter heat pain detection thresholds or painfulness of long thermal stimulation in normal skin. We conclude that, at infusion rates in the low- to mid-antiarrhythmic range, lidocaine has no effect on acute nociceptive pain but does have a limited and selective effect on secondary hyperalgesia. ⋯ The efficacy of systemic lidocaine in nonneuropathic pain remains uncertain. This study investigates the effect of systemic lidocaine on experimental-induced hyperalgesia in 25 volunteers. Hyperalgesia was induced by using an experimental pain model that uses heat and capsaicin in combination. Systemic lidocaine showed a selective effect on secondary hyperalgesia.
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Reg Anesth Pain Med · Sep 2000
Randomized Controlled Trial Clinical TrialEffect of oral mexiletine on capsaicin-induced allodynia and hyperalgesia: a double-blind, placebo-controlled, crossover study.
Mexiletine is a sodium channel blocker that has been used for the treatment of a variety of neuropathic pain syndromes. A recent double-blinded placebo-controlled study concluded that it was ineffective in the treatment of allodynia associated with neuropathic pain. However, this study failed to achieve adequate plasma levels of mexiletine. This was a study in healthy volunteers that sought to push the drug to dose-limiting side effects and then evaluate the effects on human experimental pain. ⋯ Mexiletine has minimal effects on human experimental pain. It is severely limited by side effects and tolerable doses seem to be void of effects on normal neurosensation and facilitated pain induced by capsaicin and thermal heat pulses.