Anesthesiology
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Randomized Controlled Trial Clinical Trial
Different mechanisms of development and maintenance of experimental incision-induced hyperalgesia in human skin.
To determine the mechanisms of postoperative pain, the effects of local anesthesia on development and maintenance of surgical incision-induced hyperalgesia were evaluated in a crossover, double-blinded, placebo-controlled human study using 17 subjects. ⋯ Pretraumatic injection of lidocaine reduces primary hyperalgesia more effectively than does posttraumatic injection, but only for a short period after incision. The spread of secondary hyperalgesia is mediated peripheral nerve fibers, but when secondary hyperalgesia has fully developed, it becomes less dependent on or even independent of peripheral neural activity originating from the injured site.
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Local anesthetics were suggested to have a potential for neurotoxicity in both clinical reports and laboratory experiments. Growing neurons have been shown to be susceptible to the toxic effects of local anesthetics in culture. These findings have generated the interest in factors that would rescue the neurons affected by the neurotoxicity of local anesthetics. ⋯ The NTFs-brain-derived neurotrophic factor, glial-derived neurotrophic factor, and neurotrophin 3-were demonstrated to support the reversibility of lidocaine-induced growth cone collapse in primary cultured sensory neurons, an effect that was concentration- and time-dependent. Because similar effects were observed after tetracaine washout, the supporting effects of NTFs may not be specific to lidocaine.