European journal of pain : EJP
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Anticonvulsants are widely used for the treatment of neuropathic pain. Here we review the evidence for a number of peripheral and central changes after nerve injury that may provide a basis for the mechanisms of action of anticonvulsant therapies. ⋯ The focus of this article is on anticonvulsants; however, opioids and antidepressants can also be effective in increasing inhibitions to control of pain in a manner similar to that of the enhancement of gamma-aminobutyric acid (GABA) function by antiepileptic drugs. A brief account of these approaches to neuropathic pain is also given.
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Randomized Controlled Trial Clinical Trial
Clonidine for treatment of postoperative pain: a dose-finding study.
The aim of this double-blind randomized study was to evaluate the optimal intravenous dose of clonidine administrated during the peri-operative period, after lumbar hemilaminectomy for herniated disk repair. The "optimal intravenous dose" was defined as that providing minimal analgesic request, stable haemodynamic profile and a minimal sedation score during 12h after extubation. Eighty adult patients, ASA physical status I-II, undergoing lumbar hemilaminectomy for herniated disk (L(4)-L(5), L(5)-S(1)) were included in the study. ⋯ In conclusion, this study demonstrates that, when sedation and analgesic effect of clonidine is required, 3 microg/kg bolus dose followed by a continuous infusion of 0.3 microg/kg per hour has to be considered the optimal intravenous dose. The higher dose of intravenous clonidine (5 microg/kg) produced better analgesia but the degree of hypotension and sedation was more severe and longer lasting; it required ephedrine administration and careful monitoring of the patient. On the other hand, the bolus of intravenous clonidine 2 microg/kg (group C) was less effective in terms of pain relief but with similar side-effects to the 3 microg/kg dosage (group B).
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Clinical Trial Controlled Clinical Trial
Pavlovian conditioning of opioid and nonopioid pain inhibitory mechanisms in humans.
Learning processes such as respondent or Pavlovian conditioning are believed to play an important role in the development of chronic pain, however, their influence on the inhibition of pain has so far not been assessed in humans. The purpose of this study was the demonstration of Pavlovian conditioning of stress-induced analgesia in humans and the determination of its opioid mediation. In a differential classical conditioning paradigm two different auditory stimuli served as conditioned stimuli and mental arithmetic plus white noise as unconditioned stimulus. ⋯ Pain tolerance was affected by naloxone whereas pain threshold was not. The data of this study show that stress analgesia can be conditioned in humans and that it is at least partially mediated by the endogenous opioid system. Learning processes also influence pain inhibitory processes in humans and this effect might play a role in the development of chronic pain.
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Some patients who have sustained whiplash injuries present with chronic widespread pain and mechanical allodynia. This single-blind, case control matched study of 43 chronic whiplash patients sought to examine psychophysical responses to non-noxious stimuli and their relationship to psychological profiles. Symptom Check List 90-R (SCL-90-R), Neck Disability Index and Shortform McGill Questionnaire were completed prior to testing. ⋯ Pain in response to non-noxious stimulation over presumably healthy tissues suggests that central mechanisms are responsible for ongoing pain in at least some whiplash patients. The additional findings of pain on punctate pressure and hyperalgesic responses to heat and cold stimuli are consistent with enhanced central responsiveness to nociceptor input. These results have important therapeutic and prognostic implications.
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The continuous intrathecal infusion of drugs with implantable and programmable pumps is commonly used for the treatment of otherwise intractable pain and spasticity. There is now a consensus that it is possible to use mixtures of two or even three drugs in selected cases. ⋯ These values are determined from the desired quantity of each drug to be infused in 24h, the concentration of each drug solution and the volume of the reservoir. It is essential that the drugs do not react with one another, that they will remain stable in the reservoir at body temperature and that they are safe for a long-term infusion.