Pain
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Pain sensitization after partial infraorbital nerve transection (p-IONX) in mice not only presents in orofacial region, but also spreads to distant body parts. The roles of toll-like receptor 4 (TLR4) in orofacial pain and the spreading process are still unclear. Here, we found that mice with deficient TLR4 because of Tr4 gene point mutation (C3H/HeJ) or spontaneous deletion (C57BL/10ScNJ) developed tactile allodynia and thermal hyperalgesia in the vibrissal pad in a parallel way to their respective wild types (C3HeB/FeJ or C57BL/6J) after p-IONX. ⋯ The hypersensitivity, which did not spread to the vibrissal pad, was accompanied with upregulation of MyD88 in the lumbar cord rather than in the medulla. These results suggest that TLR4 participates in the spread of allodynia component of orofacial pain to distant body sites, but not trigeminal neuropathic pain or the spread of its hyperalgesia component. This study suggests that TLR4 may serve as a potential target for the management of widespread allodynia associated with orofacial pain.
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Multicenter Study
Variability in negative emotions among individuals with chronic low back pain: relationships with pain and function.
Chronic pain is associated with elevated negative emotions, and resources needed to adaptively regulate these emotions can be depleted during prolonged pain. Studies of links between pain, function, and negative emotions in people with chronic pain, however, have focused almost exclusively on relationships among mean levels of these factors. Indexes that may reflect aspects of emotion regulation have typically not been analyzed. ⋯ Spouse-observed pain and pain behaviors were also associated with greater variability in patients' negative emotions. Test of the inverse associations between negative emotion level and variability in pain and function were significant but weaker in magnitude. These findings support the notion that chronic pain may erode negative emotion regulation resources, to the potential detriment of intra- and inter-personal function.
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Observational Study
Communication about chronic pain and opioids in primary care: Impact on patient and physician visit experience.
Patients and physicians report that communication about chronic pain and opioids is often challenging, but there is little empirical research on whether patient-physician communication about pain affects patient and physician visit experience. This study video recorded 86 primary care visits involving 49 physicians and 86 patients taking long-term opioids for chronic musculoskeletal pain, systematically coded all pain-related utterances during these visits using a custom-designed coding system, and administered previsit and postvisit questionnaires. Multiple regression was used to identify communication behaviors and patient characteristics associated with patients' ratings of their visit experience, physicians' ratings of visit difficulty, or both. ⋯ The association between patient requests for opioids and patient experience ratings was wholly driven by 2 visits involving intense conflict with patients demanding opioids. Patient-physician communication during visits is associated with patient and physician ratings of visit experience. Training programs focused on imparting communication skills that assist physicians in negotiating disagreements about pain management, including responding to patient requests for more opioids, likely have potential to improve visit experience ratings for both patients and physicians.
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The exteroceptive sensory system is responsible for sensing external stimuli in relation to time and space. The aim of this study was to investigate the tempo-spatial properties of the exteroceptive system using painful laser heat and nonpainful mechanical touch stimulation. Thirteen healthy subjects were stimulated on the volar forearm using 2 paradigms: a continuous stimulation along a line on the skin and a 2-point stimulation. ⋯ Numeric rating scale increased both with line length and distance between the 2 points (linear mixed model, P < 0.001). The findings indicate that the tempo-spatial acuity of the exteroceptive system is lower for noxious stimuli than for innocuous stimuli. This is possible due to the larger receptive fields of nociceptive neurons and/or less lateral inhibition.