Pain
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Chronic pelvic pain syndrome is a multisymptom syndrome with unknown etiology. The experimental autoimmune prostatitis (EAP) mouse model of chronic pelvic pain syndrome is associated with immune cell infiltration into the prostate, expression of C-C chemokine ligand 2 (CCL2), and neuroinflammation in the spinal cord. Here, we studied CCL2 expression in tissues along the nociceptive pathway and its association with neuroimmune cells during pain development. ⋯ Myeloid derived cell infiltration into the spinal cord in EAP was observed in the L6-S2 dorsal horn. Myeloid-derived CD45 IBA1+ cells were localized with IBA1+ TMEM199+ microglia in the dorsal horn of the spinal cord in EAP, with intimate association of the 2 cell types suggesting cell-cell interactions. Finally, intrathecal administration of liposomal clodronate ameliorated pelvic pain symptoms, suggesting a mechanistic role for macrophages and microglia in chronic pelvic pain.
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Randomized Controlled Trial Multicenter Study
Intrathecal delivery of hydromorphone vs morphine for refractory cancer pain: a multicenter, randomized, single-blind, controlled noninferiority trial.
Hydromorphone is an alternative to morphine for intrathecal drug delivery system to treat refractory cancer pain; however, there is not enough clinical evidence to prove it. In our study, 233 patients from 12 different pain management centers across China were enrolled, 121 and 112 in the intrathecal hydromorphone (ITHM) and intrathecal morphine (ITMO) groups, respectively. The primary outcome was the clinical success rate, which was defined as ratio of patients achieving ≥50% pain relief. ⋯ The patient-controlled analgesia bolus change rate was lower in the ITHM group than in the ITMO group (ITHM -19.88% vs ITMO 7.79%, P < 0.01, t test) from first week. Our result shows that ITHM is noninferior to ITMO on pain relief to treat refractory cancer pain, however, at different doses and that the doses of morphine tended to increase, whereas those of hydromorphone decreased over time. Hydromorphone offers advantage over morphine in controlling BTP.
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No externally validated presurgical risk score for chronic postsurgical pain (CPSP) is currently available. We tested the generalizability of a six-factor risk model for CPSP developed from a prospective cohort of 2929 patients in 4 surgical settings. Seventeen centers enrolled 1225 patients scheduled for inguinal hernia repair, hysterectomy (vaginal or abdominal), or thoracotomy. ⋯ The c-statistics (95% confidence interval) were similar in the full validation sample and the 2 subsamples: 0.69 (0.65-0.73), 0.69 (0.63-0.74), and 0.68 (0.63-0.74), respectively. Calibration was good (slope b and intercept close to 1 and 0, respectively, and nonsignificance in the Hosmer-Lemeshow goodness-of-fit test). The validated model based on 6 clinical factors reliably identifies risk for CPSP risk in about 70% of patients undergoing the surgeries studied, allowing surgeons and anesthesiologists to plan and initiate risk-reduction strategies in routine practice and researchers to screen for risk when randomizing patients in trials.
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The voltage-gated calcium channels CaV3.1-3.3 constitute the T-type subfamily, whose dysfunctions are associated with epilepsy, psychiatric disorders, and chronic pain. The unique properties of low-voltage-activation, faster inactivation, and slower deactivation of these channels support their role in modulation of cellular excitability and low-threshold firing. Thus, selective T-type calcium channel antagonists are highly sought after. ⋯ High voltage-gated calcium, as well as tetrodotoxin-sensitive and -resistant sodium, channels were unaffected by 5bk. 5bk inhibited spontaneous excitatory postsynaptic currents and depolarization-evoked release of calcitonin gene-related peptide from lumbar spinal cord slices. Notably, 5bk did not bind human mu, delta, or kappa opioid receptors. 5bk reversed mechanical allodynia in rat models of HIV-associated neuropathy, chemotherapy-induced peripheral neuropathy, and spinal nerve ligation-induced neuropathy, without effects on locomotion or anxiety. Thus, 5bk represents a novel T-type modulator that could be used to develop nonaddictive pain therapeutics.