Articles: hyperalgesia.
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Reg Anesth Pain Med · Jun 2019
Fentanyl versus remifentanil-based TIVA for pediatric scoliosis repair: does it matter?
Opioid-induced hyperalgesia (OIH) and acute opioid tolerance have been demonstrated extensively in patients undergoing adolescent idiopathic scoliosis (AIS) repair. Remifentanil infusion has been strongly linked to both tolerance and OIH in these patients; however, the impact of using an intraoperative fentanyl infusion has not been well studied. This study aims to determine if patients undergoing operative management of AIS have decreased opioid consumption and pain scores when an intraoperative fentanyl infusion is used as compared with a remifentanil infusion. ⋯ Despite concerns for hyperalgesia and acute tolerance, remifentanil is widely used for intraoperative opioid infusions for surgical correction of AIS. This retrospective study examined a practice change from intraoperative remifentanil to intraoperative fentanyl as a potential approach to avoid OIH. Surprisingly, patients receiving fentanyl intraoperatively showed increased postoperative opioid use and pain scores in the first 24 hours postsurgery compared with the prior cohort receiving remifentanil. Substitution of fentanyl for remifentanil during surgical correction of AIS does not appear to solve the problem of OIH or acute tolerance. Prospective studies are needed to confirm this unexpected result.
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The mechanisms responsible for the persistence of chemotherapy-induced peripheral neuropathy (CIPN) in a significant proportion of cancer survivors are still unknown. Our previous findings show that CD8 T cells are necessary for the resolution of paclitaxel-induced mechanical allodynia in male mice. In this study, we demonstrate that CD8 T cells are not only essential for resolving cisplatin-induced mechanical allodynia, but also to normalize spontaneous pain, numbness, and the reduction in intraepidermal nerve fiber density in male and female mice. ⋯ Moreover, adoptive transfer of cisplatin-educated CD8 T cells to Rag2 mice prevented CIPN development induced by either cisplatin or paclitaxel, indicating that the activity of the educated CD8 T is not cisplatin specific. In conclusion, resolution of CIPN requires in vivo education of CD8 T cells by exposure to cisplatin. Future studies should examine whether ex vivo CD8 T cell education could be applied as a therapeutic strategy for treating or preventing CIPN in patients.
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Trigeminal spinal subnucleus caudalis (Vc) neurons that project to the ventral posteromedial thalamic nucleus (VPM) and parabrachial nucleus (PBN) are critical for orofacial pain processing. We hypothesized that persistent trigeminal nerve injury differentially alters the proportion of Vc neurons that project to VPM and PBN in a modality-specific manner. Neuroanatomical approaches were used to quantify the number of Vc neurons projecting to VPM or PBN after chronic constriction injury of the infraorbital nerve (ION-CCI) and subsequent upper-lip stimulation. ⋯ However, the percentage of pERK-IR VPM projection neurons was also greater in ION-CCI than sham rats after capsaicin but not mechanical lip stimuli. The present findings suggest that persistent trigeminal nerve injury increases the number of Vc neurons activated by capsaicin or mechanical lip stimuli. By contrast, trigeminal nerve injury modifies the proportion of Vc nociceptive neurons projecting to VPM and PBN in a stimulus modality-specific manner and may reflect differential involvement of ascending pain pathways receiving C fiber and mechanosensitive afferents.
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Inflammation or injuries of the trigeminal nerve are often associated with persistent facial pain and its sequelae. A number of models have been described to study trigeminal pain in rodents, but the long-lasting behavioral consequences are unknown. This study characterizes the impact of a distal infraorbital nerve injury, called DIONI, which consists of ligature and transection of distal fibers of the infraorbital nerve. ⋯ They were mildly overactive in some tasks but without disruptions of circadian rhythms or impact on social structure. They adopted a strategy to maintain licking with fewer nosepokes, presumably trying to avoid mechanical stimulation of the snout. The results suggest that mice with DIONI develop strong aversive memories and some cognitive inflexibility, but create adaptive strategies to cope with the persistent trigeminal hypersensitivity.
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Case Reports
Prevention of post-operative hyperalgesia in a heroin-addicted patient on methadone maintenance.
The exponential increase in chronic opioid consumers resulted in more challenges regarding post-operative pain management. Considering the usual hyperalgesic response to pain and the increased opioid-tolerance, a multidrug approach should be desirable. ⋯ Ketamine can effectively reduce opioid requirements in chronic opioid users on methadone maintenance therapy and should therefore be considered promptly as part of a multimodal perioperative analgesia management in this category of patients.