Pain
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Randomized Controlled Trial Comparative Study Clinical Trial
Intravenous adenosine alleviates neuropathic pain: a double blind placebo controlled crossover trial using an enriched enrolment design.
Adenosine analogs produce analgesic actions in nociceptive paradigms and alleviate manifestations of neuropathic pain in nerve injury models in rodents. In humans, previous work indicates an analgesic effect for adenosine administered intravenously in postoperative and neuropathic pain. In this double blind placebo controlled crossover trial, we used an enriched enrolment design to determine the effects of intravenous adenosine (50 microg/kg/min over 60min) on neuropathic pain. ⋯ Adenosine also led to a significant reduction in pinprick hyperalgesia, but not in allodynia. Three patients from Phase 1 of the trial experienced long term resolution of their pain following intravenous adenosine (5,16,25 months). The results of this study support previous reports that indicate intravenous adenosine alleviates neuropathic pain and hyperalgesia.
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Comparative Study
Involvement of the anterior pretectal nucleus in the control of persistent pain: a behavioral and c-Fos expression study in the rat.
The anterior pretectal nucleus (APtN) participates in nociceptive processing and in the activation of central descending mechanisms of pain control. In this study we used behavioral tests (incisional pain and carrageenan-induced inflammatory pain) and c-Fos expression changes to examine the involvement of the APtN in the control of persistent pain in rats. A 1cm longitudinal incision through the skin and fascia of the plantar region (large incision), or a 0.5cm longitudinal incision through the skin only (small incision) was used, and the postoperative incisional allodynia was evaluated with von Frey filaments. ⋯ In the ipsilateral spinal cord, the incision-induced increase in the number of positive cells was significantly reduced in the superficial lamina and significantly increased in the deep lamina of animals previously treated with bupivacaine in the contralateral APtN. In conclusion, the integrity of the APtN is necessary to reduce the severity of the responses to persistent injury. The results also are in agreement with the current notion that persistent noxious inputs to the APtN tonically activate a descending mechanism that excites superficial cells and inhibits deep cells in the spinal dorsal horn.
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Comparative Study
Age differences in postoperative pain are scale dependent: a comparison of measures of pain intensity and quality in younger and older surgical patients.
As the population ages, research into the assessment of postoperative pain in older patients is urgently needed. The reliability and validity of most pain scales for the assessment of acute postoperative pain in the elderly remain to be demonstrated. The present study reports the analysis of age-related patterns on three pain scales (McGill Pain Questionnaire, MPQ; Present Pain Intensity, PPI; and Visual Analog Scale, VAS) completed by younger (n=95, mean age=56.4+/-5.8 years) and older (n=105; mean age=66.8+/-2.7 years) men following radical prostatectomy. ⋯ POD effect sizes did not differ between the scales or age groups suggesting that all three scales have comparable sensitivity within an age group. However, the different results between the scales for the effect of age suggests that the VAS is not sufficiently sensitive to detect age differences. Therefore, age differences in postoperative pain are better captured by verbal descriptions of pain qualities than non-verbal measures of intensity.
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A 47-year-old patient with cancer pain underwent implantation of an intrathecal drug delivery device. When the patient suffered from an infection with fever, pain on injection into the catheter and an elevated number of granulocytes in the cerebrospinal fluid 7 weeks later, radiologic examination showed an encapsulation of the catheter tip. Concentrations of morphine and morphine-6-glucuronide in the cerebrospinal fluid suggested transport of morphine into the systemic circulation via the vascularisation of the encapsulating membrane. After antibiotic therapy and removal of the catheter, morphine was administered intravenously with a one to one conversion ratio.
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Amitriptyline, nortriptyline, imipramine, doxepin, desipramine, protriptyline, trimipramine, and maprotiline are tricyclic antidepressants (TCAs) used orally in treating major depressive disorders. Recent studies showed that amitriptyline is more potent in blocking the sciatic nerve functions in vivo by local injection than bupivacaine, a long-acting local anesthetic. We therefore tested whether various TCAs could likewise act as local anesthetics in vivo after single injection via the rat sciatic notch. ⋯ With this in vitro expression system, TCAs appear more potent than bupivacaine as Na(+) channel blockers in Nav1.5 Na(+) channels. We suggest that the ability of TCAs to pass through various membrane barriers within peripheral nerve trunks is crucial to their local anesthetic efficacy in vivo. TCAs with a tertiary amine appear more effective in penetrating these membrane barriers than TCAs with a secondary amine.