Pain
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We evaluated the construct validity (including responsiveness), reliability, and feasibility of the Pain Squad multidimensional smartphone-based pain assessment application (app) in children and adolescents with cancer, using 2 descriptive studies with repeated measures. Participants (8-18 years) undergoing cancer treatment were drawn from 4 pediatric cancer centers. In study 1, 92 participants self-reported their level of pain twice daily for 2 weeks using the Pain Squad app to assess app construct validity and reliability. ⋯ These findings provide evidence of the construct validity, reliability, and feasibility of the Pain Squad app in children and adolescents with cancer. Use of real-time data capture approaches should be considered in future studies of childhood cancer pain. A video accompanying this abstract is available online as Supplemental Digital Content at http://links.lww.com/PAIN/A169.
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Previous studies have reported that 15% to 25% of patients treated for breast cancer experience long-term moderate-to-severe pain in the area of surgery, potentially lasting for several years. Few prospective studies have included all potential risk factors for the development of persistent pain after breast cancer surgery (PPBCS). The aim of this prospective cohort study was to comprehensively identify factors predicting PPBCS. ⋯ Higher preoperative diastolic blood pressure was associated with reduced risk of PPBCS (OR: 0.98 per mm Hg, P = 0.01). Both patient- and treatment-related risk factors predicted PPBCS. Identifying patients at risk may facilitate targeted intervention.
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The pathophysiology and underlying pain mechanisms of temporomandibular disorders (TMD) are poorly understood. The aims were to assess somatosensory function at the temporomandibular joints (TMJs) and to examine whether conditioned pain modulation (CPM) differs between TMD pain patients (n = 34) and healthy controls (n = 34). Quantitative sensory testing was used to assess the somatosensory function. ⋯ There was a significant CPM effect (increased PPT) at both test sites during painful cold application in healthy controls and patients (P < 0.001). There was no significant difference in the relative CPM effect during painful cold application between groups (P = 0.227). In conclusion, somatosensory abnormalities were commonly detected in TMD pain patients and CPM effects were similar in TMD pain patients and healthy controls.
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Treating neuropathic pain continues to be a major clinical challenge and underlying mechanisms of neuropathic pain remain elusive. We have recently demonstrated that Wnt signaling, which is important in developmental processes of the nervous systems, plays critical roles in the development of neuropathic pain through the β-catenin-dependent pathway in the spinal cord and the β-catenin-independent pathway in primary sensory neurons after nerve injury. Here, we report that Wnt signaling may contribute to neuropathic pain through the atypical Wnt/Ryk signaling pathway in rats. ⋯ Spinal blocking of the Wnt/Ryk receptor signaling inhibits the induction and persistence of neuropathic pain without affecting normal pain sensitivity and locomotor activity. Blocking activation of the Ryk receptor with anti-Ryk antibody, in vivo or in vitro, greatly suppresses nerve injury-induced increased intracellular Ca and hyperexcitability of the sensory neurons, and also the enhanced plasticity of synapses between afferent C-fibers and the dorsal horn neurons, and activation of the NR2B receptor and the subsequent Ca-dependent signals CaMKII, Src, ERK, PKCγ, and CREB in sensory neurons and the spinal cord. These findings indicate a critical mechanism underlying the pathogenesis of neuropathic pain and suggest that targeting the Wnt/Ryk signaling may be an effective approach for treating neuropathic pain.
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Patients with neuropathic pain commonly present with spontaneous pain, in addition to allodynia and hyperalgesia. Although evoked responses in neuropathic pain models are well characterized, determining the presence of spontaneous pain is more challenging. We determined whether the chronic constriction injury (CCI) model could be used to measure effects of treatment of spontaneous pain, by evaluating dorsal horn neuron (DHN) spontaneous activity and spontaneous pain-related behaviors. ⋯ The median rate of spontaneous activity in the CCI group (12.6 impulses per second) was not different from the sham group (9.2 impulses per second). Also, there was no change in DHN spontaneous activity after sciatic nerve block with bupivacaine. Our findings suggest that CCI as a neuropathic pain model should not be used to measure effects of treatment of spontaneous pain driven by the peripheral input.